What Minuit knows about stock Jeep radios

[Minuit]

 

What Minuit Knows About Stock Jeep Radios

 

Got a question? Need one of these radios repaired, or want to buy one? Check out my website!

 

What is this?

Simply put, it's a compilation of my findings regarding the factory radios installed in Jeeps 84-96 with a focus towards those that can be installed in Comanches.

 

How come there's a link to a business website at the very top of what's supposed to be an informational write-up? Is this just a disguised ad for a business you own?

No. This writeup came long before any money changed hands, but after a while members of this community began asking me to repair and upgrade their radios.

 

A warning in case you want to poke inside.

First of all, most of these radios are made in Japan. The many "Philips" screws on them are in many cases Japanese Industrial Standard (JIS) fasteners. These screws are usually marked by a circular divot in the head of the screw. A typical Philips screwdriver will ruin these screws very easily. A screwdriver that specifically states it works with JIS screws is highly recommended if you want to play around with these radios. I have been extremely impressed with my set of Vessel screwdrivers made in Japan. JIS screwdrivers often make better Phillips screwdrivers than actual Phillips screwdrivers, too.

 

What Will Fit?

Let's get this out of the way. Every single radio I discuss in this article will physically fit in the dashboard of any Jeep XJ Cherokee/Wagoneer or MJ Comanche from 1984-1996. The dashboard opening never changed until 1997. These will also fit in right hand drive Jeep Cherokees.

 

All radios featured in this article have detachable mounting brackets to allow installation in different vehicles. Mounting brackets are available to mount factory Jeep radios in the following vehicles:

-1984-1996 Jeep XJ Cherokee/MJ Comanche

-1985-1991 Jeep SJ Grand Wagoneer

-1987-1995 Jeep YJ Wrangler

-1985-1987 AMC Eagle

-1988-1992 Eagle Premier/Dodge Monaco

-1985-1987 Renault Alliance/Encore

 

These will not fit under any circumstances

- Any radio larger than the DIN standard size, including most Chrysler radios

- CJ shaft style radios unless using a Metra 87-15-1007 kit, which supports certain shaft radios.

 

Vehicle connections differ between the 3 eras. Chrysler and Late AMC era radios should have labels somewhere on them showing the connector pinouts, but they are sometimes missing or unreadable. Please note that the year splits given are a general rule, not set in stone! I have seen pictures of brand new 1989 year trucks with AMC radios in them, for example.

 

Early AMC Era (??-1984)

You're on your own. Information about these is very hard to come by. Connectors change every few years, and most use a "common ground" style of speaker setup.

 

1984-1985

The 1984 and 1985 lineup of AMC radios is weird. Identical to their later versions when installed in a car, but they have significant internal and wiring differences. Most notably, they feature as many as 4 individual, small connectors for different functions. I do not recommend purchasing these on this basis, but these radios can be re-wired to match the more adaptable Late AMC Era connection style. Certain internal differences make some of these radios (especially the RX-141) more difficult to repair. 

 

Stereo 1985 radios use a "common-negative" style of speaker connection, with the negative signal shared between the front and rear speakers of each channel. Mono units instead ground the negative side of the speaker.

 

Late AMC Era (1986-1987)

Late AMC Era radios have 2 8-position, free hanging connectors with some pins not used. The male connector carries speaker signals, and the female connector powers the radio. The radio will function with the "speaker" connector unplugged but will not produce sound. All late AMC era radios have identical connector pinouts, but depending on the model some pins are not used. Do not rely on color to determine the function of the wire. Pins are labeled with letters on the connectors themselves - a very intuitive setup. When buying a radio, keep in mind that in the AMC era, having 4 speakers was a somewhat rare option. Not all radios are pinned for all 4 speakers! If the radio has a "fade" control, it is equipped to drive 4 speakers.

 

Stereo radios of this era use conventional speaker connections, with balanced + and - terminals. Mono radios continue to ground the negative speaker terminal.

http://i.imgur.com/UMlZMwUl.gif

The diagram is drawn looking into the front face of the connector.

 

Chrysler Era (1988-1996)

All Chrysler era Jeep radios use a 13-pin connector, which almost always plugs directly into the radio. Some very, very early Chrysler era radios have a free-hanging connector, but you are not likely to find this. Almost all Chrysler era radios have all pins present for 4 speakers and a power antenna regardless of whether or not the vehicle had them. If the vehicle the radio was originally installed in only had 2 speakers, a jumper harness was usually used. Speaker connections are completely conventional, with + and - balanced connections.

http://i.imgur.com/luIPdFFl.jpg

The diagram is drawn looking into the radio's connector.

 

Aftermarket harnesses:

Metra 70-1002

Metra 71-1002

 

The Radios

 

This section is for information on the individual decks within the scope of this writeup. The information given (if it is available) will be as follows:

 

- The deck's part number (and manufacturer number if known). The part numbers may differ based on the vehicle the radio was originally installed in - the part numbers given are for XJ and MJ applications.

- Pictures of the deck at night, and in daylight if available.

- Radio type

- Display type

- Years offered in Jeep vehicles

- Manufacturer

- Power output if known. Sometimes, the datasheets for internal amplifiers are available, and measurements are given if known. Otherwise, I will make a guess as to its power.

- Aux input compatible? With some creativity all radios are capable of accepting an auxiliary input, but radios that have "Yes" marked accept it more easily, typically by applying a stereo signal to easily accessible test points. If soldering is required, "aux input compatible" is not marked.

- Distinguishing features

- Pros - Nice things about the deck.

- Cons - bad features of the deck not counting any problems.

- Common problems, and the causes, if known.

 

Early AMC Era (??-1984)

The wild west, as far as this writeup (which is intended to roughly cover the lifetime of the XJ Cherokee until 1996) is concerned. I currently have no information on the connectors used, and a dizzying array of different twin-shaft style radios were used. This was the very beginning of the digital tuning era, and radios older than 1984 are far out of my area of expertise.

 

3238861 / 8936000033

Type: AM/FM/Cassette

Display: Vacuum fluorescent

Years: 1983-1985

Manufacturer: Mitsubishi

Power: 13Wx2 RMS at 8 ohms.

 

Features: 

5 station memory per band

Compatible with four speakers

Mechanical tape loading and ejection, using the same design as the RX-141 and RX-161.

 

Pros:

- A shaft radio with surprisingly good specs, equivalent to the RX-161.

- The internal circuitry seems quite repairable, although it is very tight due to the small chassis.

 

Cons:

- Common-negative speaker wiring (negative wire shared between front and rear speakers of each channel)

- Uses entirely different connectors than later radios.

- Shaft mounting, so an adapter plate will need to be used to install it in a later dash.

 

Not considered worthy of an actual model name for some reason, the 3238861 is what you get when you put an RX-161 into a hydraulic press and smash it until it's as small as it can possibly be. This is the radio used in the 1984 and 1985 Grand Wagoneer, and was optional on the AMC Eagle and various other AMC and Renault products. By this point, the twin shaft style of chassis was being stretched to its limits, and it shows. This isn't your daddy's mono AM shaft radio, and I suspect one in good working order will make you quite happy. This one won't fit in your MJ, though, unless you come up with an adapter to mount it in the dash.

 

 

 

Late AMC Era (1985-1987)

This is where things start to get good. The Late AMC Era radios are extremely well made, durable, and may surprise you with their sound quality. The cassette decks are also extremely heavy. Power is still lacking by modern standards, and they were teamed up with 8 ohm speakers from the factory. As a rule none of these radios have a clock. Internally these radios are very intricate and difficult to service. These aren't unique to Jeeps. They can also be found in AMC's other products, including Renault cars and the AMC Eagle. Don't believe me? Search "Renault Alliance interior" on Google images and you'll find several pictures of French cars with these very same radios in them. It might sound like there's a lot of downsides, but these radios sound good, look proper in our trucks' interior, and have an '80s retro charm that nothing else does.

 

The 1985 versions are unique as described above. These differences lie primarily in their connection methods.

 

A dizzying array of radios were offered in this period. AM only, AM-FM with either 2 or 4 speakers and with or without electronic tuning, and 2 different cassette decks were offered.

 

RX-135 / RX-131

8956001651 / 8936001522 / 8936001268

 

Type: AM/FM/Cassette

Display: Vacuum fluorescent, green or light blue

Years: 1985 (RX-131), 1986-1987 (RX-135)

Manufacturer: Mitsubishi

Power: 13Wx2 RMS at 8 ohms.

 

Features: 

Motorized tape ejection

Dynamic Noise Reduction

Music Program Search (MPS) - finds individual tracks on cassettes

Seek sensitivity (DX)

5 station memory (per band)

 

Pros:

- Vacuum fluorescent display!

- Very good sound quality, especially for the time

 

Cons:

- Exceptionally rare

- These are getting very old, and will probably require service

- Does not use the Jeep/Eagle factory connector - uses two separate plugs for power and speakers, so an adapter will need to be made to install this into a post-1987 vehicle.

 

The RX-135 was the most technologically impressive of the AMC era radios, and is one of the very rarest. Its most distinctive feature is its noise reduction system, as indicated on the cassette door: it uses National Semiconductor's Dynamic Noise Reduction. Similar in nature to the far more common Dolby-B noise reduction system but much different in operation, DNR is also available when listening to AM and FM radio.

 

These radios do not appear to have been common even when new. They are extemely scarce on the market today, especially in good condition. They show up as original equipment in Jeeps very infrequently, more commonly found in the Renault Alliance and similar vehicles. They may have been used into Chrysler's ownership period - notably, I have seen one installed in a brand new Comanche in a 1989 Jeep dealer training brochure.

 

The unit pictured to the right was installed in a 1986 Jeep Comanche, but I have doubts that it was original. A very helpful member at ComancheClub.com spotted it in a junkyard. I am currently working on repairing it to full function.

 

Like all AMC radios, the RX-135 remembers station presets even if the battery is disconnected. My testing has shown that the radio will remember stations for as much as 12 hours with no power, possibly longer.

 

RX-161 / RX-141

8956001910 / 8956002148 / 8956002197

 

http://i.imgur.com/sqMeHVtl.jpg

Type: AM/FM/Cassette

Display: Vacuum fluorescent, light blue

Years: 1984-1985 (RX-141), 1986-1987 (RX-161)

Manufacturer: Mitsubishi

Power: 13Wx2 RMS at 8 ohms.

 

Features: 

Dolby-B Noise Reduction

Seek sensitivity (DX)

5 station memory (per band)

 

Pros:

- Vacuum fluorescent display!

 

Cons:

- Rare

- These are getting very old, and will probably require service

- Does not use the Jeep/Eagle factory connector - uses two separate plugs for power and speakers, so an adapter will need to be made to install this into a post-1987 vehicle.

 

The counterpart to the RX-135. It seems to appear more frequently in Jeeps, and is more traditional overall. It offers fewer features than the RX-135, lacking track searching, motorized cassette ejection, and forgoing DNR in favor of the much more common Dolby noise reduction. 

 

These radios are by no means common, but appear to be much more common in Jeeps. I have seen these radios in all Jeep products of this time, including Grand Wagoneers, highly optioned Cherokees, 1987 Wranglers, and Comanches. This radio appears to have co-existed with the RX-135. My 1987 Jeep Trucks brochure includes both as optional extras. In the Grand Wagoneer, this seems to be the only radio offered between 1985 and 1987, and possibly later depending on supply. The 1985 version of this radio is unique, with different connections. Its model designation is the RX-141.

Like all AMC radios, the RX-161 remembers station presets even if the battery is disconnected. My testing has shown that the radio will remember stations for as much as 12 hours with no power, possibly longer.

 

AR-7650

8956001384 / 8936001127 / 8936001521 / 8956001573

 

 

http://i.imgur.com/y5xR5Aal.jpg

Type: AM/FM

Display: Vacuum fluorescent

Years: 1986-1987

Manufacturer: Mitsubishi

Power: 13Wx2 at 8 ohms. The circuitry is perfectly stable at 4 ohms, but this unit does not have an external heat sink so heat is a concern.

 

Distinguishing features:

- Larger than usual vacuum fluorescent screen is located on the top right corner.

- No clock, like other AMC units.

- Seek mode works in both "directions"

 

Pros:

- Vacuum fluorescent display!

 

Cons:

- Rare

- Does not use the Jeep/Eagle factory connector - uses two separate plugs for power and speakers, so an adapter will need to be made to install this into a post-1987 vehicle.

- Overheating is a potential concern when running 4 4-ohm speakers.

 

With electronic tuning, 4-speaker output, station memory, and bi-directional seeking, the AR-7650 is the most advanced non-cassette AMC radio.

 

As indicated by the very wide variety of part numbers, this radio was used in a large number of different products. These radios can be found in any AMC product during their time period, and are among some of the most common AMC radios, although they are by no means common. These can be found with a number of logos printed on the screen. I have seen the pictured AMC logo, the Jeep logo, and the Renault logo on these units.

 

I have briefly used the pictured example in one of my Comanches, and it made a good impression, with good sound quality (as good as one can get with 27 year old base model speakers, anyway) and a clean, attractive look.

 

AR-7600

8956001980 / 8956001843 / 8982200408 / 8936001430 / 8936001520

Type: AM/FM

Display: Mechanical tuning dial

Years: 1986-1987

Manufacturer: Mitsubishi

Power: 13Wx1 RMS at 8 ohms.

 

Features: 

5 station memory

Manual AM and FM tuning

Tone control

 

Pros:

- Very good AM and FM reception

- Uncomplicated, and easy to keep running

 

Cons:

- Mono sound only, and the speaker connector is only pinned up for two speakers

- Grounded negative speaker terminal (+ signal and ground, rather than + and - signals).

- Does not use the Jeep/Eagle factory connector - uses two separate plugs for power and speakers, so an adapter will need to be used to install this into a post-1987 vehicle.

 

The AR-7600 is fairly common by the standards of AMC radios, but in 2019 there aren't many reasons other than nostalgia to install one in your vehicle. This radio was used as one of the base options in just about everything AMC was shoving DIN-sized radios into, and is quite easy to find on the used market. If you want the best possible FM reception, this seems like a good candidate. Without any antenna plugged in, I could still pick up radio stations from surprisingly far away easily using this radio. Plus, it's just fun to use. The radio presets are stored mechanically - pull the button out and push it back in to save the current station.

 

One fringe benefit of mechanically tuned radios is that they can pick up any radio station from 530-1610 kHz and from 88-108 MHz, no matter what frequency. This may be of interest in Europe, as most European countries have more closely spaced radio stations than North America.

 

 

Chrysler Era (1988-1996)

Just before Chrysler purchased American Motors Corporation in 1987, Mitsubishi and Automatic Radio Corporation developed a new generation of radio head units for the various Jeep vehicles being introduced and updated. The result was a significant technological improvement over the previous AMC radios. Specs are improved across the board, with better AM-FM reception, more power, improved reliablility, and one massive improvement: common use of 4-ohm speakers. These new radios did away with the flashy '80s look of the previous models, and introduced a black, businesslike aesthetic that still looks relatively modern. 

 

For the most part, these radios are exclusive to Jeeps. Certain models can also be found in the Eagle Premier.

 

The Chrysler era head units, with their grown-up, businesslike look, represent the overwhelming majority of the available factory Jeep radios. A large variety of functionally equivalent units are available, and all share the same functional features. All are capable of driving a full set of 4-ohm speakers without concern of overheating, and will plug in to the same connectors and attach with the same mounting brackets. In addition, these units are Jeremy's Radio Emporium's bread and butter - full support for these radios, including repair, modification, and customization options are available - all but a couple of models are offered by JRE with auxiliary inputs. Unlike with the AMC era, there is no vast chasm of functionality from one unit to another - there is no "best" radio in this era, so pick the one you like the look of the most.

 

Chrysler radios have one integrated 13-pin connector for all functions. All pins are installed, even when the vehicle is not equipped with those features. Connector pinouts are identical, and speaker connections are conventional - "Feed" represents the positive signal, and "Return" represents the negative signal. The diagram is printed facing into the radio.

 

RX-170

8956002467

http://i.imgur.com/9FNgzeEl.jpg

 

http://i.imgur.com/qTMWFeUl.jpg

Type: AM/FM/Cassette

Display: LCD, green with green pixels

Years: 1988

Manufacturer: Mitsubishi

Power: 18Wx2 RMS at 4 ohms.

 

Features: 

Dolby-B Noise Reduction

Fully motorized cassette transport

Seek sensitivity adjustment (DX)

10 station memory (per band)

 

Pros:

- Many more button panel bulbs than later radios, resulting in more consistent illumination.

 

Cons:

- Can be difficult to find in working order. Most of these radios require service by now.

- Internal construction is entirely different from later decks, meaning parts availability is poor.

 

The RX-170 is the first of the Chrysler era radios (note the AMC style part number), and a transitional model. My service manual for the RX-170 even indicates AMC as the manufacturer. The short-lived green-on-green display makes its debut here, and all following Chrysler era radios share its basic design. It is by far the most internally intricate of the Chrysler Era, and further models are greatly simplified - to the trained eye, the RX-170 looks more like an AMC era unit on the inside than a Chrysler one. Otherwise, build quality is exceptional. In fact, this is one of the heaviest factory Jeep radios!

 

Sadly, the RX-170 also introduced a notoriously unreliable cassette mechanism. While not a major issue in 2018, it is something to look out for. Common issues include motor seizure, constant cycling of the motorized loading mechanism, auto reverse flip-flop, and excessively high playback speed. On the bright side, I have "serviced" (replaced) many of these cassette modules, and the belts have always been in excellent condition.

 

This radio officially appears during only the 1988 model year, but appears to have been gradually introduced, and may have carried over into 1989. 

 

Automatic Radio AM-FM-Cassette

8956003020 / 8956003021

Type: AM/FM/Cassette

Display: LCD, green with green pixels

Years: 1989-1990

Manufacturer: Automatic Radio

Power: Unknown, likely unimpressive

 

Features: 

Dolby-B Noise Reduction

Seek sensitivity control (DX)

10 station memory (per band)

 

These radios, built in Korea by Automatic Radio, are the black sheep of the Chrysler era. While appearing very similar to the RX-170 of 1988, the Automatic Radio series are built to a significantly lower standard of quality. Potentiometers are unshielded, the display lighting (even when fully functional) is uneven and unattractive, and their reliability seems to be a step below the Mitsubishi offerings. Also, the buttons are brown by design, not because the radio in the picture is dirty.

 

Pros:

- The cassette player seems to be reliable!

 

Cons:

- Too bad about the radio it's attached to.

 

The pictured radio was shipped to me for evaluation by another very helpful member at Comanche Club. It was found to be in very poor condition and likely not worth repairing. I even found an un-clipped component lead inside!

 

Information on these is even more difficult to come by than for the Mitsubishi radios, so specs such as power output are unknown.

 

RX-171

56002467

http://i.imgur.com/22E2EPCl.jpg

Type: AM/FM/Cassette

Display: LCD, green with green pixels

Years: 1991

Manufacturer: Mitsubishi

Power: 20Wx2 RMS at 4 ohms

 

Features: 

Dolby-B Noise Reduction

Fully motorized cassette transport

Seek sensitivity control (DX)

10 station memory (per band)

 

Pros:

- Low noise, with quite high quality sound.

- Construction quality is excellent overall, with many high quality parts being used.

- Neat looking display

 

Cons:

- Can be difficult to find in working order. Most of these radios require service by now.

- The cassette module, as with all of these radios, sucks.

 

For the 1991 model year, Mitsubishi's offering was an iteration on the previous RX-170, greatly simplifying the internal layout, improving power, and updating certain components. Internally, it is the base from which all later Chrysler-era cassette decks were built. The display is carried over from the RX-170, but otherwise shares very few components.

 

Sadly, the cassette mechanism is arguably even less reliable than the one in the RX-170, and has all of the same issues.

 

The RX-171 was the last radio to use Jeep's green-on-green display, and the last to not have a clock function.

 

RX-172

56009004 / 56009005

http://i.imgur.com/WXIj3evl.jpg

 

http://i.imgur.com/9mzxfn2l.jpg

Type: AM/FM/Cassette

Display: LCD, light green with black pixels

Years: 1992-1993

Manufacturer: Mitsubishi

Power: 20Wx2 RMS at 4 ohms

 

Features: 

Dolby-B Noise Reduction

Clock

Fully motorized cassette transport

10 station memory (per band)

 

Pros:

- Low noise, with quite high quality sound.

- The new display is easier to read in some light, and can still be read in daylight with the bulbs burnt out.

- Newer, and thus less likely to be in need of service

 

Cons:

- The cassette module, as with all of these radios, sucks.

- The LCD backlight bulbs are very, very likely to be burnt out.

 

For the 1992 model year, Jeep introduced the RX-172. Internally, it is very similar to the earlier RX-171 with many of the same features - the main difference is the display. A new black-on-green LCD was introduced, which is easier to read in some light conditions. A clock was also introduced, as Jeep was transitioning its vehicles from using separate dash clocks to ones integrated into the radio.

 

While easier to read, the new display has one major downside: the bulbs. It is exceedingly difficult to find a regularly used 1992 or later radio with fully functioning bulbs in the display, unless it has been serviced. Replacing these bulbs is an advanced task - certain parts must be bent out of shape to be removed, solder points lie approximately half an inch from a critical ribbon cable, and the display must be re-assembled by a careful hand to prevent damage.

 

 

RX-173

56007214 / 56007215

http://i.imgur.com/SGmuX9Wl.jpg

 

http://i.imgur.com/SHTKeiol.jpg

Type: AM/FM/Cassette

Display: LCD, light green with black pixels

Years: 1994-1996

Manufacturer: Mitsubishi

Power: 20Wx2 RMS at 4 ohms

 

Features: 

Dolby-B Noise Reduction

Clock

Music Program Search (MPS)

Fully motorized cassette transport

10 station memory (per band)

 

Pros:

- Sound quality is slightly improved from earlier models, although the difference is slight.

- The display is easier to read in some light, and can still be read in daylight with the bulbs burnt out.

- Newer, and thus less likely to be in need of service

 

Cons:

- The cassette module still sucks.

- The LCD backlight bulbs are very, very likely to be burnt out.

 

Installed in Jeeps from 1994 until the Cherokee's 1997 revamp, the 56007214 is probably the most common of any of the Chrysler-era radios, and one of the most reliable. Externally identical to the RX-172 except for the "MPS" lettering on the seek button, the changes introduced with the RX-173 lie under the skin. Parts are simplified and modernized - the RX-173 is the first Jeep radio to heavily use surface-mount components, for example. A Motorola amplification chip was used, replacing the Toshiba TA8210AH chips used previously. Subjectively, this results in a slightly fuller, more powerful sound.

 

The cassette mechanism was reworked, adding Music Program Search, a feature not seen in Jeep cassette players since 1987. Reliability of the cassette mechanism seems to be better, but still not great. All of the same flaws still exist, although the motors seem to be less likely to seize up.

 

82300393 / 82300392

 

Type: AM/FM/CD

Display: LCD with green backlight

Years: Available 1994-1996, possibly produced in one run in 1993.

Manufacturer: Mitsubishi

Power: 18Wx2

 

Distinguishing features:

- It plays them newfangled Compact Discs

- The only Jeep radio that you can probably make a serial number registry for

- 6 AM, 12 FM station presets

 

Not surprisingly, there is very little information out there about these due to their extreme rarity. Internally, they share a significant number of parts with the RX-173, and the internal layout is what I would describe as "an RX-173 run through a blender" - lots of surface-mount components are used, and we are beginning to see more advanced features than on previous analog radios. Unfortunately, these have a lot of problems - the faceplates are quite fragile, the power supply is fragile, the FM tuner requires removal for any service and likes to mute itself. Build quality is a touch below the more mainstream Mitsubishi-made Jeep radios. Their rarity was no doubt helped by their price - roughly $300 in 1994 - about $500 in today's money.

 

My current estimates give a production number of approximately 1200 based on a very close grouping of observed serial numbers, with the 4 units I have personally examined being within 800 serial numbers - including two units 13 serial numbers apart. I have acquired one for myself, and I will be restoring it, adding auxiliary input, and installing it in my '91.

 

One production variation I have seen that makes absolutely no sense is the volume knob, which seems to vary without rhyme or reason. Some have a volume knob with a white tick mark, while others are unmarked. 3070927 has a tick mark, and 3070914 doesn't. 

 

If you own an 82300393, consider sharing the serial number! I would like to get as many serial numbers together as possible to determine a total production number.

 

AR-7750

8956002466 / 8936001568

Type: AM/FM

Display: Green LCD with green incandescent backlight

Years: 1988

Manufacturer: Mitsubishi

Power: 18Wx2 RMS at 4 ohms.

 

Distinguishing features:

- Unique external design

- Unique fade knob - it sticks out more

 

Pros:

- Many more button panel bulbs than later radios, resulting in more consistent illumination.

 

Cons:

- Can be difficult to find in working order. Most of these radios require service by now.

- Internal construction is entirely different from later decks, meaning parts availability is poor.

- Bass and treble potentiometers are prone to becoming "scratchy"

 

The AM-FM companion to the RX-170, the AR-7750 mirrors its design in many ways. Essentially the RX-170 without a cassette player, it features every innovation of its counterpart. In addition, it was the first radio to feature front-mounted, sliding tone controls. While distinguishing, they are far more exposed to the elements than standard knobs and become "scratchy" very easily.

 

Sadly, I am unable to report on the AR-7750's sound quality - the pictured unit looks almost brand new inside and out, but will not produce sound.

 

Automatic Radio AM-FM

8956003018 / 8956003019

 

http://i.imgur.com/QuMivWNl.jpg

Type: AM/FM

Display: LCD, green with green pixels

Years: 1989-1990

Manufacturer: Automatic Radio

Power: Unknown, but it makes pretty loud pop noises

 

Features: 

Seek sensitivity control (DX)

10 station memory (per band)

Lots of popping and crackling noises

 

Pros:

- ???

 

Cons:
- Sound quality below expectations

- Rudimentary construction compared to Mitsubishi-built decks.

 

I defend most factory Jeep radios, because I genuinely believe they are good radios with redeeming features. The Automatic Radio decks are the exception. A step down in both build quality and sound quality from anything made by Mitsubishi in the Chrysler era, I struggle to find anything to brag about with these. The brown buttons look out of place in the MJ's interior, and the entire radio just feels low quality. Also, who decided to make the buttons brown?

 

That's sad, because the pictured radio might as well be brand new. 

 

AR-7751

36001568 / 56002466

http://i.imgur.com/0C1Zwnql.jpg

 

http://i.imgur.com/AO3Q3dol.jpg

Type: AM/FM

Display: LCD, green with green pixels

Years: 1991

Manufacturer: Mitsubishi

Power: 20Wx2 RMS at 4 ohms

 

Features: 

Seek sensitivity control (DX)

10 station memory (per band)

 

Pros:

- Reliable

 

Cons:

- Bass and treble potentiometers are prone to becoming "scratchy"

 

The last major change to the Chrysler-era AM-FM radios, the AR-7751 was the counterpart to the RX-171. All following AM-FM radios share a virtually identical layout - the only change to later versions worth noting is the display. Typical of a Chrysler-era AM-FM unit, the AR-7751 is essentially a slightly simplified RX-171 without a cassette player.

 

The AR-7751, and later AR-7752 and 7753, are some of the very most reliable Chrysler-era radios. Unusually for a Mitsubishi product, their internal layouts are very simple. I generally find these units to give very few issues, unless treated poorly or exposed to extreme heat.

 

These also appear in the Eagle Premier and Dodge Monaco as the base audio option, with the pictured green panel lighting and no "Jeep" stencil near the volume knob.

 

AR-7752

56009001 / 56009003

 

http://i.imgur.com/oRj3q5il.jpg

Type: AM/FM

Display: Black LCD with light green incandescent backlight

Years: 1992-1993

Manufacturer: Mitsubishi, made in Singapore

Power: 20Wx2 at 10% THD at 4 ohms. Not 2-ohm stable.

 

Distinguishing features:

- LCD screen updated to match the 56009004. A clock was also added, and minor revisions were made to the internal circuitry. All Mitsubishi-built AM-FM radios are identical on the inside. The only notable differences are the early (black) vs. late (green) display styles.

 

Pros:

- Reliable

 

Cons:

- Bass and treble potentiometers are prone to becoming "scratchy"

 

Essentially the AR-7751 with a clock, these share roughly 90% of their parts with their predecessor, including basic circuit board layout, amplification, and basic construction. The display has been updated to match the RX-172, and it shares all parts. Clock functionality is the same as the RX-172, as are all features other than the tone controls, which are still unusually prone to corrosion.

 

Jeremy's Radio Emporium has serviced more AR-7752s than any other radio - they are as reliable as Jeep radios get. Other than the typical display bulb issue, I very rarely come across an AR-7752 or AR-7753 that are "flaky" or nonfunctional

 

AR-7753

56007519

http://i.imgur.com/uaCYtKGl.jpg

http://i.imgur.com/11fsfdPl.jpg

Type: AM/FM

Display: LCD, light green with black pixels

Years: 1994-1996

Manufacturer: Mitsubishi

Power: 20Wx2 RMS at 4 ohms

 

Features: 

Clock

10 station memory (per band)

 

Pros:

- Reliable

 

Cons:

- Bass and treble potentiometers are prone to becoming "scratchy"

 

The AR-7753 is essentially identical to the AR-7752. In my many detailed examinations of these radios, I have not found a single substantial difference that an end user or technician would notice. Even as someone who has worked on dozens of these radios, I struggle to tell the difference between them.

 

It is important to note that the AR-7753 does not appear to have benefitted from any of the technical improvements from the RX-172 to the RX-173. Its circuit board layout resembles the RX-172 more than the RX-173, and surface mount components are relatively few in number. In addition, the AR-7753 retains the same Toshiba TA8210AH amplifier chip used by all Jeep radios since the RX-171 and AR-7751.

 

Science Projects

 

- Adding Auxiliary Input to the RX-170, RX-171, RX-172, and RX-173 AM/FM/Cassette Radios for $3.30 in parts

All of the above listed Chrysler era tape decks share the same board layout for our purposes. For testing purposes, these radios have two pins labeled TP371 and TP471 on an extension board located behind the volume and tone controls. If a signal is put through these two pins (TP371 for the left channel and TP471 for the right channel), it will be played through the speakers, and the radio or cassette volume will be cut. When no signal is being played to these pins, the stereo functions as normal. This allows for an auxiliary input to be added very easily, and without any permanent changes. Depending on your attention to detail, the install can be very slick - the only noticeable difference will be an aux cord somewhere on the interior. I prefer to run mine through the center console. The best radio to use for this procedure in my experience is the 56002467 by far, as it will have the least background noise.

 

As the main talker-abouter on this forum about this technique, I'll admit that it isn't perfect. You're asking a 20-30 year old piece of audio equipment to do something it wasn't technically designed to do. However, its drawbacks can be minimized.

 

- Your phone is meant to drive headphones, not a car radio. Without a pre-amp, this won't be as loud as the radio or cassette player so you'll lose out on part of the radio's power. An external amplifier will also fix this, and is a good idea anyway. I've also seen "sound shockers" that supposedly make the aux input much louder without needing power, although I've never tried one.

- The radio can "bleed through" the aux signal and be noticeable in the background. I'll show you a way to minimize this, or if you have a 56002467 deck, eliminate it entirely.

 

To access the inside of the radio, remove the top cover. It is held on with one Philips screw and two "snaps" at the rear. Once the screw is removed the cover can be pried up at the rear and lifted out. Once the cover is removed, you'll see this. The inside looks scary, but nothing else needs to be removed.

http://i.imgur.com/Zs7vnsul.jpg

The extension board we need is located right behind the bass and treble knobs. Pins TP371 and TP471 are visible among several resistors and other parts directly below the long yellow connector in the middle left of the picture. On the model 8956002467, this board is on its side in a similar location.

 

http://i.imgur.com/qfUZTN0l.jpg

The top pin is TP371, which corresponds to the left stereo channel. The bottom pin, TP471, corresponds to the right stereo channel. Putting any audio signal through these pins will play it through the speakers (and attenuate everything else). Volume, treble, bass, fade, and balance can be adjusted as normal.

 

On radios I build for sale or for service, I build custom fully shielded shielded cables with female 3.5mm jacks - nothing you can buy off the shelf meets the specifications I need. The details of this method are beyond the scope of this article. A simpler solution, and one that I have used in the past with good results, is to use a 6 ft. long cable with a male end. This involves as little electrical work as possible. Earlier revisions of this article mentioned a 3-pin Molex connector, but some tests revealed this to be far too fragile for general use. 

 

Here is a pre-made Digi-Key cart of all of the parts you'll need if you're working on a tape deck. The connectors specified are designed to be crimped with a special 28 AWG open barrel crimper, but the home gamer can get away with soldering them.

 

In summary, if you're using the cable I linked to:

- Green wire attaches to a metal surface on the radio

- Red wire attaches to pin TP371

- White wire attaches to pin TP471

If you're using any other cable, check which color code corresponds to what function, as they do vary. I removed the cassette module to take a better picture, but you shouldn't need to.

http://i.imgur.com/N67olnel.jpg

 

I can make you an aux input cable for your 56002467, 56009004, or 56007214. The cost is $25 shipped and the cable can be made to your specification, with either a female or male 3.5mm connector at the end.

 

 

Spotted an inaccuracy? Got a question, complaint, concern, demand, cry of outrage, or AMC era tape deck? PM me on CC, or e-mail me at:

jeremy at radio-emporium dot com

 

2/21/17: Correction - the 92-93 radio is the 56009004, not the 56006932, and it does not have the MPS function. Added what very little I know about the AMC radios.

3/11/17: Added section on 8956001910. To be filled in later once I get it.

5/2/17: Added 8956002467.

5/10/17: Added 56009001, and a few new photos to replace old blurry ones. Updated 56009004, as I now own a working one!

6/24/17: Big edit. Changed the order to be descending chronologically, and added some more fluff to explain compatibility.

 

 

If you are not reading this article on the "DIY Projects and Tech Writeups" section of the "ComancheClub.com" website OR on radio-emporium.com, it has been plagiarized!  All pictures are property of Jeremy's Radio Emporium and I do not authorize the redistribution of any images or information contained in this article on any web site other than ComancheClub.com. All audio equipment featured in this article was either my property at one point, or belongs to a customer who contracted my equipment repair services. I certify that the information contained in this article is correct to the best of my knowledge, but make no guarantees.

[buxmj]

Great info Jeremy! I am so mad at myself for discarding my original stereo. I cannot remember which one it was but I kept it for a long time in a drawer in the garage, it was barely used, #$&*#@!!

 

Ashamed and kicking myself,

 

Buck.

[Minuit]

Thanks as always Buck!

[A-man930]

Damnit now I'm gonna start searching for a radio.

Any walk through on how to hookup to an external amplifier?

[Minuit]

Damnit now I'm gonna start searching for a radio.

Any walk through on how to hookup to an external amplifier?

 

I'll be adding a small amp to the '91 soon so I'll be sure to document the process. Here's an amateurish schematic of the way I'm going to do it.

 

 

I want to keep my truck's harness intact, so my method is a little bit more complicated and I need extra adapters. If that doesn't matter to you, your installation will be a little simpler. The amp I'll be using is small enough that it can run off the truck's existing radio fuse, so that means I won't need to run additional wiring from the battery (unless I hook it up and it blows the radio fuse all of the time, we'll see.) If you're using a bigger amp, you'll need to run a power wire from the battery. With a factory radio you'll either need an amp that accepts speaker level inputs (the signal that's been amplified already by the radio), or buy a converter that converts the radio's output to RCA low level (what you'd normally use with an aftermarket head unit). Normally, an aftermarket head unit will have RCA jacks on it, which bypasses the radio's internal amp for a cleaner signal. The factory radio obviously doesn't have that, so it's a little bit of a compromise since the radio's internal amplifier adds a little bit of distortion.

[A-man930]

With a factory radio you'll either need an amp that accepts speaker level inputs (the signal that's been amplified already by the radio), or buy a converter that converts the radio's output to RCA low level (what you'd normally use with an aftermarket head unit). Normally, an aftermarket head unit will have RCA jacks on it, which bypasses the radio's internal amp for a cleaner signal. The factory radio obviously doesn't have that, so it's a little bit of a compromise since the radio's internal amplifier adds a little bit of distortion.

 

 

So is there not a way to intercept the signal before its amplified?  

[Minuit]

Not with a factory radio. haha nope it's totally possible

 

Sent from my LG-D850 using Tapatalk

[HOrnbrod]

 

With a factory radio you'll either need an amp that accepts speaker level inputs (the signal that's been amplified already by the radio), or buy a converter that converts the radio's output to RCA low level (what you'd normally use with an aftermarket head unit). Normally, an aftermarket head unit will have RCA jacks on it, which bypasses the radio's internal amp for a cleaner signal. The factory radio obviously doesn't have that, so it's a little bit of a compromise since the radio's internal amplifier adds a little bit of distortion.

 

 

So is there not a way to intercept the signal before its amplified? 

 

Well, there's a way, but it'll require picking off the L/R audio channels before they go to the radio final amp stage and wiring them out to RCA chassis jacks. Not hardly worth the effort, plus you'll ruin the factory unit's originality.

 

I like this small external amp application and will be looking forward to the results. I could use a little more volume with the new AM/FM/CD factory unit I recently put in, especially with the CDs. Probably have to upgrade the mediocre Sony Exploder speakers too...........

[Minuit]

On 3/6/2017 at 9:43 PM, hornbrod said:

 

On 3/6/2017 at 12:37 PM, A-man930 said:

 

On 3/6/2017 at 12:49 AM, Minuit said:

With a factory radio you'll either need an amp that accepts speaker level inputs (the signal that's been amplified already by the radio), or buy a converter that converts the radio's output to RCA low level (what you'd normally use with an aftermarket head unit). Normally, an aftermarket head unit will have RCA jacks on it, which bypasses the radio's internal amp for a cleaner signal. The factory radio obviously doesn't have that, so it's a little bit of a compromise since the radio's internal amplifier adds a little bit of distortion.

 

 

So is there not a way to intercept the signal before its amplified? 

 

Well, there's a way, but it'll require picking off the L/R audio channels before they go to the radio final amp stage and wiring them out to RCA chassis jacks. 

 

 

I was going to say that and it's maybe something worth pursuing, but it's hardly a practical solution for the home gamer that just wants an original looking dash. Since this is a more technical thread, I probably should figure it out and report back. Truthfully, though, if you're going that far, even as someone who hates aftermarket radios I think you're probably better off getting one. Yeah, that's what I said before I started a business doing exactly this kind of thing

 

At this point I'm just guessing but I think you could tap the pre-amp signals from the same board that has the aux input pins at one of two connectors (you'll want the signal right after it passes through the volume and tone controls). I need to get my hands on another deck that I don't mind screwing up for experimentation purposes. Hard to find these things in junkyards these days.

[A-man930]

 

 

 

With a factory radio you'll either need an amp that accepts speaker level inputs (the signal that's been amplified already by the radio), or buy a converter that converts the radio's output to RCA low level (what you'd normally use with an aftermarket head unit). Normally, an aftermarket head unit will have RCA jacks on it, which bypasses the radio's internal amp for a cleaner signal. The factory radio obviously doesn't have that, so it's a little bit of a compromise since the radio's internal amplifier adds a little bit of distortion.

 

 

So is there not a way to intercept the signal before its amplified? 

 

Well, there's a way, but it'll require picking off the L/R audio channels before they go to the radio final amp stage and wiring them out to RCA chassis jacks. 

 

 

I was going to say that and it's maybe something worth pursuing, but it's hardly a practical solution for the home gamer that just wants an original looking dash. Since this is a more technical thread, I probably should figure it out and report back. Truthfully, though, if you're going that far, even as someone who hates aftermarket radios I think you're probably better off getting one.

 

At this point I'm just guessing but I think you could tap the pre-amp signals from the same board that has the aux input pins at one of two connectors (you'll want the signal right after it passes through the volume and tone controls). I need to get my hands on another deck that I don't mind screwing up for experimentation purposes. Hard to find these things in junkyards these days.

 

 

I'm only curious and interested in doing this for the sake of the look of the factory unit.  An aux. input and ability to use a readily available 2 or 4 ch. amplifier w. a crossover would have me making the jump.  

 

I do indeed hate the cheesy aftermarket headunits in our dash.  

[Minuit]

 

 

I like this small external amp application and will be looking forward to the results. I could use a little more volume with the new AM/FM/CD factory unit I recently put in, especially with the CDs. Probably have to upgrade the mediocre Sony Exploder speakers too...........

 

 

 

Installed the KTP-445u today. I followed my schematic exactly and it worked without any problems. Here's a pic (before I wrapped it up in tape) of my harness:

 

 

I installed the amp on its side behind the gauge cluster, basically in the same position that Renix trucks have their ECU. That's really the only place to put even a small amp in the MJ's dash and still be close to the original radio plug. I suppose next to the TCU would also be a good place, but you'd have to extend some wiring. My limiting factor as far as packaging went was that the input (radio-amp) harness was extremely short. It's the part above the two white plugs in the picture. The provided input harness is about 6" long once you cut off the RCA jacks and combined with my radio-amp adapter, it was only just long enough to reach. The output harness (left side of pic) is WAY too long for my needs, since I was going from the amp back into the factory wiring. If I would've known there would be so much extra wire I would've cut off about a foot off of the output harness. The power and ground leads are about the right length to reach to the dash ground and the fusebox.

 

There's a lot more wiring going on behind the radio now, but the original plug tucks in the space to the right of the radio and the adapters fit behind the climate controls. I was expecting to have a tough time getting the radio back in, but it wasn't a problem. The amp doesn't get anywhere near as hot as I thought it would, so that's a definite plus. The installation is completely invisible to a casual observer, and the only sign that something aftermarket is there is the add-a-circuit on the fusebox. On the add-a-circuit I used two 15A fuses - one protecting the original circuit, and one protecting the amp. The radio and amp don't share a fuse. Since this is just a small amp, I don't think the extra load on the fusebox is cause for concern, but if the amp was fused at any more than 15A I would be running a new power wire from the battery.

 

Other than that, it's an amplifier. It makes music louder. I tested with both of my radios and the 2467 still runs out of bass at about half volume and the more powerful 7214 does a little better (limitations of speaker level inputs, you see) so the gain will have to be adjusted accordingly. The gain settings (there's one for front and rear) are set at about 50% from the factory, and that's enough to turn the volume knob on the factory radio basically into an on-off switch. I have the gains set at about 1/6 now, but I might turn them up a tiny bit later once I give it a test on the road. One big downside of how I had to install the amp is that it's a huge PITA to adjust the gain controls. The gain controls are on the input side of the amp, which is facing up inside the dash. Really wish they were somewhere else, since I'll have to take the gauge cluster out to adjust them.

 

Overall, having about an hour of listening time with it, I'd say it does the job nicely. Just don't expect miracles since with a factory radio you're stuck with using speaker level inputs. One thing I noticed is that after turning the key on the amp takes a second or so to turn itself on (in speaker level input mode it turns on when it senses a signal coming from the radio, so you won't need a remote turn on wire), so don't turn the volume up right after starting the truck or you'll be in for a very rude awakening once the amp wakes up.

 

Parts list:

 

- KTP-445U amp: $150 from Crutchfield, available elsewhere cheaper but Crutchfield has 2-day shipping to TN and I needed it quickly. Comes with output and input harnesses.

- Metra 70-1002 adapter - plugs into original radio harness plug

- Metra 71-1002 adapter - plugs into radio

- A metric crapton of uninsulated butt splices (mostly 18-22awg but some 14-16awg for power leads) as well as adhesive lined heatshrink tube (probably used about 2' of heatshrink in total)

- One uninsulated ring terminal to attach to instrument panel ground, 16-22awg

- Add-a-circuit fusebox tap with 2 15A fuses, I cut off the tacky looking blue butt splice and used my own.

- Zipties to secure amplifier to truck

[HOrnbrod]

Nice run down - thanks. The 82300393 CD player I'm using is a bit deeper in structure and I had a hell of a time stuffing it in there. I do want the external amp in that cavity, so will be looking to find a smaller footprint amp than the 90W KTP-445U amp you used. Probably will be a 2-channel unit with a little less wattage.

[A-man930]

Excellent. Although your review has convinced me further that I'd really rather not amplify speaker-level signals :)

[Minuit]

Excellent. Although your review has convinced me further that I'd really rather not amplify speaker-level signals :)

 

To each his own but I'm very happy with how it turned out. I can blast Led Zeppelin out of the tape deck with the windows down at 60 with no distortion, so mission accomplished in my book. Definitely couldn't do that before.

[Minuit]

After a long search I've scored a like new 8956001910 AMC Dolby radio (the one in the video), so I'll be finding out its secrets soon!

[A-man930]

Good deal! I'm gonna keep an eye out for one of these things.

[Minuit]

 

I think I might know a way to get aux input and maybe RCA jacks on this (the volume knob contacts are very conveniently located). Need to get a female Jeep/Eagle plug adapter to plug it into a truck, but I hooked it up to some speakers and a tool battery and it works very well. Sounds pretty good too.

 

Fun fact: the plugs used on this radio are the exact same plugs as used on the worthless IR keyless entry system, so I butchered a couple of those connectors to make the "truck" end of the radio harness.

[Minuit]

Hey look, here's the 1988-only 8956002467, the very first Chrysler tape deck! Distinguishable by it's fader knob, which sticks out a little more. Also, the chassis and internal design is quite different.

(Is it time to admit I have a problem?)

 

 

 

 

It works, but the tape deck transport constantly cycles (common problem) and the paint on some of the buttons is worn off. Both easy fixes.

[HOrnbrod]

What Minuit knows about stock Jeep radios

 

What's with the third person?  :rotfl2:

[Minuit]

Minuit wanted to make sure that everyone knew that Minuit knows all of this information. Minuit can change the title if it offends you

 

:D

[EatSleepJeep]

This is some great info, keep it coming.

[Minuit]

This is some great info, keep it coming.

 

Thank you very much. I'm kind of surprised by how popular this has been. Thought I was the only one who cared about the factory radios. I have 2 radios I haven't put in a vehicle yet (the 8956007214 that came in last weekend and the 8956001910 which I just got the factory service manual for) so I'll get off my @$$ and do that probably this coming weekend.

 

I have everything I need to make an AMC to 13 pin Jeep/Eagle plug adapter, so I'll probably put the 1910 I just got in the '89 soon. On the bench it sounded great, but I need to study the wiring diagrams to see how I can neatly make it play from an aux in before it finds a permanent home in a vehicle of mine.

 

Here's what I don't have yet. I don't have a working 56009004, an AMC DNR, any of the '84 shaft radios or any of the pre-92 AM/FM only radios. I don't really have much interest in the AM/FM only Chrysler radios since they don't have the TP371 and TP471 pins, so I doubt you'll see those unless I get one very cheaply. So if you don't count the AM/FM and ultra rare '84 radios, this writeup is almost complete.

 

Edit from the future: I have a good technique for aux input on the AM-FMs now.

[Minuit]

I have a work in progress aux input solution for the 8956001910 (the AMC radio I recently bought). The NC8500 pre-amp this deck uses has similar attenuation features as the later Chrysler decks, and when tapping into its inputs with the standard aux cable I use there is negligible bleed-through. There are test points but the pins on the pre-amp are right under your nose so you might as well use them. More details... soon.

 

It's roughly as powerful (with only 2 4-ohm speakers as to not risk overheating) as the 2467, probably a little less. Still haven't put it in a truck yet. Other than cool factor, this probably wouldn't be my first choice just because of how rare they are, and the possibility of overheating problems.

[NC Tom]

Hey look, here's the 1988-only 8956002467, the very first Chrysler tape deck! Distinguishable by it's fader knob, which sticks out a little more. Also, the chassis and internal design is quite different.

(Is it time to admit I have a problem?)

 

It works, but the tape deck transport constantly cycles (common problem) and the paint on some of the buttons is worn off. Both easy fixes.

This post reminds me. At 8pm on March 31, 2017, the stock radio in my 88 went missing. It was in okay shape. The tape didn't work quite right and the first two radio station presets were pretty worn . . . Hey!

[Minuit]

While we're on the subject of '88 radios, the one pictured is no longer in my possession. I sold it to a member on here and performed a basic service including adjusting the tape deck, replacing the buttons and giving it it a good cleaning up.

 

Before, with worn out buttons, etc.

 

The tape deck worked, and played at the proper speed. I usually find these to play slightly fast for some reason. However, when ejecting the tape the transport would cycle back and forth, and never give you the tape back.

 

That's a very common problem. To fix it, carefully bend the tab circled in red outwards. If it doesn't depress a switch next to it enough, the transport will cycle endlessly. After bending the tab, the deck should spit out the tape without taking it in again. You should have to push the tape in for the automatic transport to kick in.

 

The capstans, play head, and rollers looked great, and the belt was in good shape. I doubt this radio has played many tapes. If you want to replace the belt, it's on the underside of the cassette module under a protective plate. For this service I elected not to.

 

I then replaced the worn buttons and replaced the foam backing behind them. The buttons now stand to attention as they should and feel much nicer to press.

 

After a good cleaning, and unsticking the treble and bass knobs, it looked as good as it ever has. Like a new old radio! These '88 radios have some "early version weirdness" - the faceplates are unique, the internal layout is different, and illumination bulbs are soldered on rather than in twist-lock bases.