Bringing a RX-135 Radio Back to Life

[MagicJames]

 

 

The RX-135/RX-131 radio was a nice factory option in Jeeps from roughly 1984 through to 1987. Although it was a bit of a pricy option but made by electronic tuning in Japan. They were very durable and simple. The RX-161/RX-141 was a simialr design and had the red memory button positioned in the top right instead of the bottom right. These are great looking radios and have a cassete deck. 

 

 

Now if you find one in decent condition in the yard or on ebay don't trash it, you can send it to me :) or you can try and fix it. If they're dry and haven't been mesed with they can usually be brought bakc to working condition with just a bit of work. 

 

First for the connectors these radio has 2 harnesses, one for the power and one for the speakers. Usually you won't have the two connectors but fom what I knw about there is one comany that sell the connector set new fro 15 bucks. Its from Crunchfield and here is the link.

https://www.crutchfield.com/S-QvSfNxfUQAL/p_120701000/Metra-70-1000-Receiver-Wiring-Harness.html

 

 

Now after you plug into the two connectors go ahead and set up a small 12V battery. You want the ground wire on the negative and the battery on the positive. Then to power up the radio connect the AC/ignition wire to the positive, this is af if your opening the key contact. The radio should power on with a beatifial green pannel. If you want to simulate turning on the lights in th truck connect the panel lamp wires to the positive also. Your back light behind the radio and also the tiny blue bulb on the top should illuminate. if it doesnt you can try replacing the tiny bulb. To get sound connect a matching pair from the speaker connector to the postive and negative of a speaker. So left front-ve and left front +ve for example. You can shove a paperclip in the antenna if that helps.  

 

 

 

 

 

 

Now we want our cassette deck working cus playing cassettes is cool af in my opinon. If the deck doesnt accept the tape pull back the balck tab on the top of the deck to simulate it taking a cassette. This cassette take up and eject is all moved y springs. so make sure theyre all lubricated with a tiny bit of WD40 and give the mechanism a small tap if its seized. 

 

 

 

If your radio takes the cassette but doesn't play or spin at all you shoudl start with the belt. Open up the bakc of the radio and look for 5 small screws in the holes. thes ehold trhe deck in place. The two top screws might be behind the balck backing form, so you might have to peel that back to get to them. Try not to strip these screw heads.

 

 

Once the screws are out the deck itslef should be abled to get lifted up from the right side with some gentle persuation. you don't need to disconnect any white connectors for it to slip out. But if you wan tto make it easier you can. If the belt is snapped or even worn out or loose you can replace it. A belt of 1.5mm to 2mm thickness and a 140 to 150 mm fold length should be fine. It is just the one belt and routed like this in the picture below. 

 

 

The two gold wheels are drievn from the motor and control the speed of the belt. Now if you get the cassettle belt working and the tape playing but it sounds like a chipmonk here's the fix. A really common issue with jeep radios is that the pinch roller gets drived out and has no grip on it. Its jop is to pinch the tape against the capstan and get the tape moving at a nice speed for the music to play clearly. If the roller is too dry the tape starts to slip and gets pulled through way to fast. So to fix this get a cotton swap and some isopropanoyl alcohol and really get agressive with rubbing the roller. You can also rub down the cassette head or the shiny silver square plate. Keep doing this until the speed settles down. 

 

[87MJTIM]

Nice work.

 

What can be done to either a RX161 or RX170?  I have one of each.

 

Can they be converted to accept BT?

 

I have read some write ups on adding AUX by eliminating the AM receiver.  Can the AUX/BT be routed thru the AM and/or the tape player?

[MagicJames]

@87MJTIMIf you want the easy way you can by a bluetooth cassette , Something like what I linked. 

however if you don't care about playing cassette you could remove the deck from inside the radio and you would technically have plenty of room to put a bluetooth audio reciver board in there. Youd need to extra room fro the step down converter to 5V. Youd run the 12V off the back fo the radio into the converted then into the chip.e You would also have the option of running an AUX out of the cassette lid. 

[ghetdjc320]

I sent my Rx171 to @Minuit Back a few years ago for this very purpose. Unfortunately, my radio or Bluetooth adapter haven’t been returned, but the results were promising. I sourced a really nice Bluetooth 5.0 module that intercepted the FM radio side. Essentially the Bluetooth itself had the aux input that we tied the fm radio to. The output went to the radio’s preamp. This eliminated the radio bleed through issue that the aux input introduced. The Bluetooth was the priority signal. The Bluetooth module itself could also be programmed to adjust a wide variety of parameters. Really cool stuff, but I guess we’ll never know if it works 

[87MJTIM]

That doesn't sound good.  I remember Jeremy had health issues then changed jobs that took a lot of his time.  He had to "step away" from the radio business and his MJ.  Hopefully, he is doing better and he can get back to his MJ soon.

 

I searched on Jeff Bezos's store (Amazon) for BT adapters.  I always read the negative review first for the issues and the date of the review.  One that I read gave a very bad review in Aug 2025 - last month.  Other reviewers gave similar comments.  Does anyone have first hand experience with BT converters and would recommend a brand?

[eaglescout526]

8 minutes ago, 87MJTIM said:

Hopefully, he is doing better and he can get back to his MJ soon.

 I can without a doubt say he is doing better. 

[ghetdjc320]

I’ll see if I can find the Bluetooth module that I picked up. Jeremy had it patched in and working. The issue we had is the output of the Bluetooth is a bit too hot for the jeep radio preamp board. I’m sure some added resistance to lower down the output voltage of the module or perhaps the input voltage from the fm receiver would take care of that. It’s the ideal scenario though once thats been taken care of. As for the radio project, well, it’s coming up on 3 years. Hoping some day to finish this up 
 

Edit: found it https://www.tinyosshop.com/index.php?route=product/product&product_id=1114

[NC Tom]

I have a refurbished 7751 and would love to know how to hook an amp to it. Specifically, an old school Rockford Fosgate Punch 75.

I can't figure it out. Schematics make my brain hurt.