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What Minuit knows about stock Jeep radios


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This seems like the best spot for radio questions.  My 1990 was a radio delete, but has the radio wiring harness, and the connectors through the door for speakers.  A previous owner had some sort of radio installed - the radio was out when i got it, but there were still speakers in the doors.  He had some... creative... wiring to get power to his radio using a spliced extension cord.

 

I picked up an RX-173 for a good price - the seller claims that it worked when he pulled it out of his vehicle - so i plugged it into the harness when i got it, but no power, no anything.

 

I'm more suspicious of my jeep's electrical vs. the radio, and am not sure of the best way to confirm where the issue is...  the PO had snipped the speaker leads from the harness to connect directly to his radio, but i'm assuming i should still get power from the harness.  The accessory power wire (purple and orange?) was also pulled out of the harness... but i'm not sure i'm getting any of the accessory power.

 

I've replaced all the fuses, but am wondering if the radio delete option didn't connect the harness to battery, or if i'm totally going down the wrong path.   I'm pretty sure the PO didn't disconnect the power, given the somewhat rigged power that was hooked up previously.  

 

Any tips on testing the power?  I'm pretty new to the electrical side of things.  I've got my multi-meter, but am not sure where to stick my leads...

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3 hours ago, QCComanche said:

This seems like the best spot for radio questions.  My 1990 was a radio delete, but has the radio wiring harness, and the connectors through the door for speakers.  A previous owner had some sort of radio installed - the radio was out when i got it, but there were still speakers in the doors.  He had some... creative... wiring to get power to his radio using a spliced extension cord.

 

I picked up an RX-173 for a good price - the seller claims that it worked when he pulled it out of his vehicle - so i plugged it into the harness when i got it, but no power, no anything.

 

I'm more suspicious of my jeep's electrical vs. the radio, and am not sure of the best way to confirm where the issue is...  the PO had snipped the speaker leads from the harness to connect directly to his radio, but i'm assuming i should still get power from the harness.  The accessory power wire (purple and orange?) was also pulled out of the harness... but i'm not sure i'm getting any of the accessory power.

 

I've replaced all the fuses, but am wondering if the radio delete option didn't connect the harness to battery, or if i'm totally going down the wrong path.   I'm pretty sure the PO didn't disconnect the power, given the somewhat rigged power that was hooked up previously.  

 

Any tips on testing the power?  I'm pretty new to the electrical side of things.  I've got my multi-meter, but am not sure where to stick my leads...

Sure.

 

A 1990 should have the following connector pinout.

chryplug.JPG.386fabd7009901eec6c539b73f71d3ff.JPG

 

And on the back of the radio:

chryrcpt.jpg.1b3df52cbd32e4a575d6e00a0fdb45ec.jpg

 

The 12V+ Constant should have battery voltage at all times. The 12V+ Switched wire should have battery voltage any time the ignition is turned to RUN or ACC. The ground is a separate wire with a 1/4" quick connect terminal, not part of the main plug. It eventually connects to the ground wire at the bottom of the metal dash frame under the headlight switch.

 

Check the DOME fuse and the RADIO (for some years, ETR) fuses. DOME controls the constant power, RADIO/ETR controls the switched power. I'm not aware of any wiring differences for a radio delete truck. There will not be speakers, but all wiring up to where the door harnesses plug in should be present. Installing a radio "should" be as simple as installing speakers, installing (or making) the small wire harnesses that run from just inside the truck under the kick panels into the doors, and plugging the radio in. The antenna may or may not have been installed from the factory - my 91 started life as a radio delete but still had the antenna installed.

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Hey there Minuit, I was taking my radio appart to tighten the volume knob like you suggested and figured I'd do a mini write-up for others wanting to do the same. Also included in the pics is the serial number tag with pinouts, which I found interesting, shame that not every manufacturer does that! And finally, about the issue of sound cutting off after a few seconds, everything was extremely clean inside except for those two capacitors that have a little bit of stuff on them... They both have flat tops still; they're not swollen. What do you think? I once had an Xbox that would shut off after a few seconds due to 3 capacitors that bursted and leaked, and it reminds me of that...

 

 

Ok! So step one for fixing that annoying loose volume knob! Remove those golden guys, mine had only two, yours might have four, then remove the bracket.20200813_185327.jpg.06dbc0941843916cca56946ab3497070.jpg

 

Step two, take out the volume and fader knobs as well as the bass and treble sliders; everything is just pressed in. Here, you can see the offending nut at the bottom of the volume hole. If you have a really thin wall 11mm socket and can reach the nut, more power to you, this would end right here.

20200813_184727.jpg.68722b41507d8a71ba4adaba22c82f94.jpg20200813_184657.jpg.8729580d5eb744062a4932a639b320e3.jpg

 

Step 3, remove these two guys, one on each side.

20200813_184618.jpg.8c4ebd3b33e1cb9dac3110c131514eb5.jpg

 

Step four CAREFULY remove the face, noting that you have these little tabs to press out both on the top and bottom of the face.

20200813_184424.jpg.1050d97762bee99917dc97defdae3de2.jpg

 

Step five tighten the nut with a deep 11mm socket, and don't lose or forget this guy before reassembly (LCD window insert)

20200813_184317.jpg.0c12cdfeb6d61ca194cd8130156c5d78.jpg

 

 

Photos for Minuit:

20200813_182858.jpg.9adac283c0dff091618afa3b8b895fdc.jpg20200813_182927.jpg.d7e6078f9ae73465eb8c42d7eae38203.jpg

 

The two suspect capacitors:

20200813_183957.jpg.6c73068f0aa441c6928feedfa28b55a2.jpg20200813_183906.jpg.60df8fb416660b77ef50754ff0890665.jpg

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17 hours ago, OldSch88L said:

Hey there Minuit, I was taking my radio appart to tighten the volume knob like you suggested and figured I'd do a mini write-up for others wanting to do the same. Also included in the pics is the serial number tag with pinouts, which I found interesting, shame that not every manufacturer does that! And finally, about the issue of sound cutting off after a few seconds, everything was extremely clean inside except for those two capacitors that have a little bit of stuff on them... They both have flat tops still; they're not swollen. What do you think? I once had an Xbox that would shut off after a few seconds due to 3 capacitors that bursted and leaked, and it reminds me of that...

 

Very nice work. As a side note: for 1991 and newer radios, the top and bottom covers have to come off before the faceplate can come off, but other than that the process is similar.

 

I'll be honest: I very rarely see capacitors cause serious issues with these radios. I measure every capacitor that I remove from these radios, and almost all of them still meet their capacitance and series resistance specs even after 30 years - they generally used very high quality capacitors in these radios. The corrosion on top would raise alarm bells for me too, though. If I were working on this radio for a customer, I'd probably want to at least remove the capacitors that show corrosion around the top and measure them with my LCR meter - but at that point, you're halfway to replacing them anyway.

 

On the very similar RX-170, those three capacitors are part of the audio amplifier circuit. A bad cap there may cause audio problems.

 

The 1988 radios are extremely well made and can be taken completely apart without de-soldering anything, but the downside of that is that there's a ton of connectors. It may be a good idea to unplug all of the various connectors, spray the contacts with contact cleaner, and plug them back in. Also, the solder joints can be trouble, but it's not as much of a problem on '88 models as it is on the others.

 

As a side note: on certain models of these radios you'll see brown stuff around the capacitors. That did not leak out of the capacitor; that's glue. Still good to get rid of it, because it can turn corrosive. Anyone who's worked on Japanese-made audio equipment from the 70s and 80s will no doubt be pretty familiar with the "brown death glue" - this is the same stuff.

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Quick question, I scored an Infinity amp and speakers from a 2001 Cherokee Limited 60th anniversary at the junkyard. I was cross-referencing wiring diagrams between the MJ's AR-7750 and the amp, so my question is: can I use the radio's power antenna wire (terminal 3) as a remote signal for the amp?

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On 8/16/2020 at 2:51 PM, sinkrun said:

Can you add a 3.5 port to a cd cassette combo out of a 2003 grand cherokee?

Negative. The ones I work on start in about 1982 (although I've recently had a rash of people asking about CJ radios from the 70s) and end in 1996 except for a few special edge cases.

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I didn't count when I took it apart.

 

All I could do is just marvel at the insanity that was before my eyes as I took this thing apart. All of this for a car tape deck. Three planetary gearsets, two motors, several completely separate linkages, a mind boggling number of what look to be sintered parts, four circuit boards, at least 30 screws, and probably 20 tiny e-clips. The fancy RX-135 tape deck is tame compared to this.

 

This thing had to have cost a fortune to put together. And it is an excellent sounding tape deck, but why? None of the mechanical craziness involved in this thing has anything to do with the sound quality. The premium cassette decks in Lincolns and Cadillacs didn't even have this many parts.

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Hello Minuit, a few quick updates followed by yet another question. I finished installing an Infinity amp and speakers from a 2001 Cherokee Limited. You were right about my truck having only front speakers stock, and they were original, and were completely blown! The cardboard cones were all wavy and were unglued from the frames. I also did a once-over on the radio like you suggested, to check connections so I unplugged all the wires and put a little dielectric grease. Good news is everything works beautifully now. But the fader doesn't seem to do anything now. Do you think it's amp-related? It worked before when I only had 2 speakers, the new rears work but the fader won't let me fine-tune it seems :(  And BTW, a big thank you for all your tips and tricks!!! :D

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32 minutes ago, OldSch88L said:

Hello Minuit, a few quick updates followed by yet another question. I finished installing an Infinity amp and speakers from a 2001 Cherokee Limited. You were right about my truck having only front speakers stock, and they were original, and were completely blown! The cardboard cones were all wavy and were unglued from the frames. I also did a once-over on the radio like you suggested, to check connections so I unplugged all the wires and put a little dielectric grease. Good news is everything works beautifully now. But the fader doesn't seem to do anything now. Do you think it's amp-related? It worked before when I only had 2 speakers, the new rears work but the fader won't let me fine-tune it seems :(  And BTW, a big thank you for all your tips and tricks!!! :D

As a general rule, I tell people to expect their fader control to stop working when using an external amp. There's quite a bit of math involved in the "why" but to cut it short, the amplifier presents a very, very light load to the radio. The fader control is designed with speakers in mind, rather than a separate amp. Unfortunately, this means that when driving a high-impedance amplifier, the fade control will pretty much do nothing. Nothing wrong with the radio or amp, and it's nothing you did, just math.

 

This is one of many reasons why any half-decent aftermarket amp will have separate gain controls for front and rear.

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On 8/16/2020 at 12:12 AM, OldSch88L said:

Quick question, I scored an Infinity amp and speakers from a 2001 Cherokee Limited 60th anniversary at the junkyard. I was cross-referencing wiring diagrams between the MJ's AR-7750 and the amp, so my question is: can I use the radio's power antenna wire (terminal 3) as a remote signal for the amp?

I guess you probably figured it out by now :dunce:

 

but short answer: yes. The power antenna's "intended" function is to activate the power antenna relay when the radio is turned on. It supplies 12V whenever the radio is turned on, and is good for up to 150milliamps or so.

 

So if you need to turn anything on with the radio such as a power antenna or amplifier, you can use the power antenna wire. Just make sure you know what current it draws.

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Hello Minuit, sorry to bother you with one of my questions again! I recently went junkyard shopping and stumbled upon an RX-135. I thought it looked cool and retro and liked the fact that it was a cassette deck so I bought it. Just got done installing it, and the sound is awesome on the cassette mode, but I have trouble with the radio mode. When I first tried it, it worked great for like 30 seconds, but since that, it pulses between static noise and and music, and the display also pulses a little bit. It's actually freaky because it really sounds like a heartbeat; I thought I was dealing with Christine's reincarnation for a moment hahaha!!! Also, if you could school me on that model; can you turn it completely off? The knob turns the sound off, but the station is still displayed, and even with the sound off, if I put a cassette in, it will play it, albeit with no sound. Is that normal?

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5 hours ago, OldSch88L said:

Hello Minuit, sorry to bother you with one of my questions again! I recently went junkyard shopping and stumbled upon an RX-135. I thought it looked cool and retro and liked the fact that it was a cassette deck so I bought it. Just got done installing it, and the sound is awesome on the cassette mode, but I have trouble with the radio mode. When I first tried it, it worked great for like 30 seconds, but since that, it pulses between static noise and and music, and the display also pulses a little bit. It's actually freaky because it really sounds like a heartbeat; I thought I was dealing with Christine's reincarnation for a moment hahaha!!! Also, if you could school me on that model; can you turn it completely off? The knob turns the sound off, but the station is still displayed, and even with the sound off, if I put a cassette in, it will play it, albeit with no sound. Is that normal?

To turn it off, turn the knob a little farther. The volume knob is also the power switch on that model. It should click.

 

The odd radio sound is likely a problem in the digital tuning circuit. The RX-135 that I put in my '89 developed that issue and I have meant to get to the bottom of it, but haven't had the chance.

 

The cassette deck is probably due for a new belt and some maintenance at this point. If the azimuth or tape speed are off, it'll sound even better after that's taken care of. If the belt breaks while a tape is running, the tape will get stuck in the radio. Don't try to pry it out.

 

I will not allow you to think for even a second that asking me radio questions is in any way bothering me.

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28 minutes ago, Minuit said:

To turn it off, turn the knob a little farther. The volume knob is also the power switch on that model. It should click.

 

The odd radio sound is likely a problem in the digital tuning circuit. The RX-135 that I put in my '89 developed that issue and I have meant to get to the bottom of it, but haven't had the chance.

 

The cassette deck is probably due for a new belt and some maintenance at this point. If the azimuth or tape speed are off, it'll sound even better after that's taken care of. If the belt breaks while a tape is running, the tape will get stuck in the radio. Don't try to pry it out.

 

I will not allow you to think for even a second that asking me radio questions is in any way bothering me.

Well that's the thing, the knob clicks, and the sound is off, but the display is still on showing the radio station, and if I put a cassette in, I can hear the cassette deck run even though I have no sound... I saw your build thread where you put a youtube video of that model radio in your truck, and the display did turn off with the volume knob "click". Second thing, when I went at the junkyard, there was a second one of these RX-135 from an XJ Wagoneer, but a dumba$$ took it out the truck, then took the radio's top cover off then left it on the rad support with the hood up, and clearly got rained on a couple of times, the truck being there since september 23rd. The metal casing started to surface rust, but the electronics looked good visually, so I put the radio back in the car, protected under the seat. I have to go back to the yard, should I grab it? For parts maybe??? And lasly, I've been on your website and noticed you sell aux cable conversions for a couple of models but not this one. Can it be converted, or should I just go with the ol' cassette-to-aux cable adapter?

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2 hours ago, OldSch88L said:

Well that's the thing, the knob clicks, and the sound is off, but the display is still on showing the radio station, and if I put a cassette in, I can hear the cassette deck run even though I have no sound... I saw your build thread where you put a youtube video of that model radio in your truck, and the display did turn off with the volume knob "click". Second thing, when I went at the junkyard, there was a second one of these RX-135 from an XJ Wagoneer, but a dumba$$ took it out the truck, then took the radio's top cover off then left it on the rad support with the hood up, and clearly got rained on a couple of times, the truck being there since september 23rd. The metal casing started to surface rust, but the electronics looked good visually, so I put the radio back in the car, protected under the seat. I have to go back to the yard, should I grab it? For parts maybe??? And lasly, I've been on your website and noticed you sell aux cable conversions for a couple of models but not this one. Can it be converted, or should I just go with the ol' cassette-to-aux cable adapter?

I see.

 

No shame in getting the other radio. These things are quite durable - sitting in the rain may not even be a death sentence as long as the corrosion is cleaned properly. At least it wasn't turned on when it got wet. Just don't spend much money for it.

 

I personally can convert almost all of these Jeep radios. What you see on my website are DIY kits. Unfortunately, there are a only a handful of radio models that have "DIY friendly" auxiliary inputs that are within the reach of your average Jeeper without much electronics experience, and kits to do just that are what you see on the site.

 

It's my official position that all of those tape adapters are awful. They're so awful and annoying to use that they are one of the reasons I got into this stuff in the first place.

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Went back to the yard today, and looks like I was mistaken... That other radio from the XJ Wagoneer was an RX-161, and the eject mechanism was seized. So, if you ever figure out that pulsation with the RX-135, let me know and I will probably send mine for a once-over and AUX convertion:L:

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