Look in the Wiring Section of the Factory Service Manual for the 1990 model year. They include wire colors and pin-outs of the connectors and their locations.

 

Keeping the factory head units alive is nearly an art at this point. I added an auxiliary input to my S5 unit that I plugged into a Bluetooth receiver. It works pretty well. Mine is such that the aux jack is active when I put a CD into the unit. The problem with this is the CD player skips. A lot. A cleaning helped and it's only really bad on the roughest of roads.

 

Regarding early CD players (car or portable), unless they have anti-skip protection or a lot of dampening, you're going to get skipping when your car passes over a bump. You just can't avoid it. I'm running a circa early 1990s CD Discman on a car mount and it works well enough but it'll still skip over a rough bump.

I also get the notion that car CD players from the 1980s to early 1990s are going to be temperamental, but something made from 1993-on by Panasonic or Clarion (standalone ones that Subaru and others offered) work pretty well. For fun, I bought a Clarion PF-20461 add-on CD player that was pulled from a junk car and a NOS Panasonic-branded one both meant for the Subaru Legacy off eBay.

If you find that the player is having trouble playing CDs, clean the lens first with a q-tip soaked in Windex or isopropyl alcohol (if the lens is plastic, stick with Windex). That's how I got a Clarion Subaru unit to consistently read and play CDs when it only played certain CDs and not others. Otherwise, they're pretty well sealed from the elements and don't require much in the way servicing.

Another little tidbit. Add-on sources like the above-mentioned CD player and CD changer controllers also have similar DIN-plugs with the same 12-volt trigger and audio pass-throughs like on the OEM and aftermarket equipment. It seems that 1995 may be the rough cut-off point where they went toward more integration.

I found that the Clarion and Panasonic (P512) -made units for the Subaru have a similar DIN plug and it is possible to build an adapter to run them as standalone players or plug into a vintage Clarion, Technics/Panasonic or Alpine unit that has a DIN plug with similar pins.

Right now, finding a separate CD player made for the Subarus can be had for under $50 off eBay and Clarion made add-on CD players for Isuzu as well. The also made factory sound equipment for Nissan and early 1990s single-DIN units have the same DIN plug for adding a CD player to. Finding a new or used unit is possible. But you will want to double-check the PIN-out on the headunit and compare that to the pin-out of the add-on unit.

One important note: avoid the 1-din in-dash add-on CD changers meant for Nissan, their mechanisms have a weak plastic gear that'll break. You'll also find that Sony 1-DIN add-on factory units for Nissans are rare and going for very high prices off eBay.

I know we're talking about the Mazda RX-7, but since Clarion made equipment for a variety of manufacturers, you might have a better chance at finding parts and working units that wouldn't look too out of place in a 1980s interior.

 

I have a S4 rx7 clarion PT-8052C cassette player that I had to take apart and I found the belts had completely disintegrated. This thread has been unimaginably helpful so thanks but I still have an issue, I’m 98% sure it’s a mechanical issue with gear alignment but it’s not obvious to me where to align the gears to or what gears need to be adjusted.
The problem that stops it from playing is not consistent and it does different things all the time, but the most constant issue is that one gear just spins and it never actually engages the tape. Any ideas what needs to be done? I have included a video of my problem here

 

So after a lot of poking around and changing gear alignments I found that the I was using too small of a belt for the small pulley gears. The 2.6 belt on the small side was fine when turned it by hand but was slipping with a load on it. It plays fine now.

 

For those asking about the Facebook weblink: It's no longer valid or needed. I've already posted images here in this thread and the Facebook album doesn't have any additional information that isn't already posted here.

Going forward, I ask that if anyone has any questions, instead of PM-ing me, please post your questions in this thread so that others can answer or contribute. I am subscribed to this thread and do get notified if someone else posts a reply.

For information about the unit's DIN-connector pin-outs, please refer to the Body Electrical section of the Factory Service Manual pages 15-114 to 15-148. It describes the types of stereo systems that were available in the 1986-88 RX-7s including the 10th Anniversary and convertible and describes each pin and function. There is also troubleshooting information.

The Factory Service Manual is the best resource for reverse-engineering an auxiliary input adapter if you're keeping the factory headunit. If you don't already have it, get it. It's available online for free and it's chock full of information.

Certain stereos also don't have internal amplification and send out a line-level audio signal that can either plug straight into an amplifier or be boosted with a line driver then tied into an amplifier.

Regarding the full-logic cassette deck, it has been several years and I have since moved onto using period-correct aftermarket stereo equipment in the car. But the eject gear should be the the one located in the right lower corner of the mechanism in the picture I originally posted. It's an L-shaped notch that the stud is supposed to be inside.

For the non-logic cassette deck, here are two pictures I took last July that show the belt routing (no, I don't know the belt sizes):

 

I'm going to add a bit more information that was in an old PM that I sent:

As to refurbishing/upgrading parts. If you're talking about board-level upgrades, I'm not the person for that. My experience with board-level upgrades are limited to changing bulbs for LEDs. Refurbishing is basically cleaning the boards up carefully using either distilled water or alcohol with a toothbrush and replacing any obvious bad capacitors with new ones of the same value. The boards on mine were fairly clean and I didn't bother with that but I did change the bulbs to LEDs using resistors in-line.

The pots and switches should all get a shot of contact cleaner and the controls worked/moved. Faderlube is still recommended for the pots and sliders.

As to the cassette section, if you are keeping it, the rule of thumb is to replace the belts with new ones, clean all the metal parts with rubbing alcohol and any rubber or plastic parts with Windex or anything that is safe to use on plastic and rubber.

As to factory replacement parts. They are long since discontinued and you won't find any. You are relegated to scavenging other units for any parts.

One last thing: I ended up switching to a period-correct aftermarket Clarion unit later because one day the tuner section of the fact unit died. It just went dead with no display. The preamp, cassette and EQ sections all still worked. I don't know why and I haven't diagnosed it. Another issue is that when you turn the headunit off with the power ****/button, it sends a snap sound through the speakers which could damage them. Again, this was an issue that I didn't diagnose.

 

This is good info. I have one of these S4 units in good condition and just need to replace the belt. Would you happen to have found a copy of the Clarion service manual? I haven't been able to find one for this unit. I have quite the collection of manuals and datasheets for the S5 units though...

 

There are service manuals still available for certain OEM models. You can buy them at Analogalley.com or High Quality Service Manuals Schematics Repair User Owner Operating Instructions Vintage Classic Audio Stereo PDF FREE

Sorry to say that I can't post any of the ones I bought on the forum.

 

Hey bud, do you think you can help me confirm something? I replaced the belts in one of these tape decks, like at the start of this thread. After reassembly, a steel pin fell out of the deck and I am trying to make sure I put it back in the correct spot. The only spot I could find that fit was a little swing arm that the pin could be inserted from the bottom. Here are the pictures of the pin, as well as the place in the tape deck I put it. The mechanism still seems free to pull in a tape and eject it. I haven't powered it on yet to see if it runs the tape, but I would appreciate it if you could provide some insight.

I am still unable to find a manual for these. I have looked at the links above, but maybe I don't know what I'm looking for...

 

Everything looks correct, but I'd take that with a grain of salt. I can't see anything out of place or obviously wrong.

If you can, I would test the unit before fully re-assembling the interior.

If there's still an issue, there should be a label on the unit with a model number. If I have the service manual for that unit, I can see if there's anything in the parts diagram.

 

That would be great. The cassette deck model is PT-8052C. This is the only S4 unit I've ever messed with. I'm still trying to work on the S5 cd player stuff. I gotta fix my bench power supply before I can test this unit. The inside of this thing is spotless though. I have not seen any of the S5 units this clean. If this thing was in a car, it was barely used. There is no rust, dust, or decay that I found in the thing. The only issue that the guy I got it from said it had was that the tape deck didn't work. The belts I took out were not cracked, dirty or anything like that. They were just too relaxed to drive the pulleys. It looked like a new unit inside, with the exception of the two belts being slack.

 

I checked the service manual that I have. Unfortunately, I do not have the service manual for that exact model. The one I have is for the PT-8051C-F. This is, presumably, an earlier revision of the model you have. There is an exploded parts view in the manual and I went over it. I didn't see a part that looks like the pin in question in the manual.

I do have the same model player that you have. So I pulled that out and I couldn't fathom where that pin could've come from.

If there's nothing loose or dangling in the tape mechanism, the only thing to do is test all its functions.

 

Ok. Appreciate you looking!

 

I have this exact deck with the short rubber band. Mine is at the cassette repair shop but some wires broke off the solder joints. If you have a pick of where the wires go internally that would be fantastic!
im looking for the ones going from the pcb around the edge that go into the pcb that is attached to the mechanism.

 

It will be impossible to help with just "some wires". A picture or a description of the wires is needed.
Edit: My foggy morning brain missed your description. I have a two of these and might be able to check for you if I have a picture. I am not familiar with these at all.

 

What model number is printed on the chassis?

 

 

if you could that would be great!

 

Here are some photographs of the interior of the PT-8051C. You didn't say what part of the unit so I'm presuming it's the cassette mechanism itself.

PT-8051C tape mechanism wiring detail closeup.

PT-8051C interior overall view

 

thanks so so much

 

Thanks for all of the help over the years. Now an issue (finally). I have a super clean N/A S4 (86) FC base model that finally needed some new rear speakers; cones were in bad shape, but the speakers did still work. Still have the factory Clarion head unit and factory amp (below the right dash); 4" speakers in front (all stock) and 6" speakers in the rear shock towers and power antenna. So I replaced the rear speakers with some new 4 ohm 6.5" Polks and took care to wire positive (blue and white wire) to positive and negative (black) to negative on the speaker. Even tested it with a 9 V battery to make sure that the old speakers were wired that way as well. But now I have no audio from either rear speaker and no audio also when I plug back in old rear speakers (am still using the OEM wiring harness for the speakers; I just made contact to the pins with wires to spade connectors on the new speaker to test before cutting any wires and didn't hear anything...aaargh Fear that something is blown in either the amp or head unit. Would like to keep the factory head unit (for looks mostly) if at all possible. Is there a way to diagnose what is messed up and if it is the amp then get it fixed or bypass it while keeping everything else stock and looking the same as factory from the interior? I don't think that the rear speakers have their own internal amp in the factory 6" rears from what I can tell so it should have been a straightforward swap old for new but that isn't how it turned out. The factory head unit still works fine, front speakers work (was going to swap them too but stopped before then...) and everything including the light bulbs, the fader, balance control, and volume control etc. work fine too so would like to keep it if I can. If the amp needs to be bypassed, is there an easy way to get the new amp into the same location or is this a whole complicated endeavor to rewire it and find another spot to put it etc.? Too bad Icemark isn't around but hopefully some others here can help!

 

Okay, first, you want to refer to the factory service manual, specifically the Body Electrical system section. There are different types of factory systems. Start on page 15-115 by identifying the type of system you have. Then follow the troubleshooting guide on page 15-121, it includes the fuses to check. Depending on your system, the amplifier is either located in each rear speaker enclosure or located inside the audio stack.

Depending on the type of audio system you have, if the amp is external and faulty, you can replace the amp with one that has line-level inputs as certain headunit models just use line-level outputs. You just need an amp small enough to fit in the area or nearby and build a simple 1/4" quick disconnect to RCA adapter to connect the amp.

 

No (obvious) amps in the rear towers; nothing there at all other than the speakers themselves. So must be with the audio stack. I don't relish the thought of having someone go in there now with all of that old ABS just ready to be snapped to bits by someone who isn't careful (i.e. almost anyone but me) but am not very experienced at doing complicated stuff (I fix the simple stuff though all of the time as needed). If the fuses are accessible, I would check them for sure though; but don't know where they are? With the stereo stuff (that requires removal of the center panel) or with the fuse bank/box below the driver's side (much easier for me to get to without messing stuff up). Also does seem weird that I blew out something given it was just a (very careful) speaker swap 4 ohm for 4 ohm but that is what it is.

 

Start with the fuses.

The main fuse block that powers the stereo is located in the driver side footwell on the left. Refer to either the fuse panel cover, the owner's manual or the factory service manual for which fuses to check.

I strongly urge you to download the body electrical, wiring diagram and body sections of the factory service manual. They will give you the locations, wires, fuses--everything you need to properly troubleshoot. Also, there are different factory systems offered in the FC. Some have an internal amplifier to drive the rear speakers, others feed a line-level signal to an external amplifier.

It sounds like you're using the correct ohm speakers, so I don't think that replacing the speakers damaged anything.

Question. What system do you have in the car? Is it just a radio? A radio with a cassette player? One with radio, cassette and equalizer? Also, for the rear speakers with amplifiers, the speakers are contained in removable black plastic enclosures with the speaker amplifiers at the bottom sides connected with four-pin connectors.