'92 with tape deck hiss

[bicknell]

I have a 92 with the graphic equalizer on the stereo. It has a very bad hiss when playing a tape with the engine running. With the engine not running, there's no hiss and it sounds great. The hiss does not change with engine RPM's, so I don't think it's ignition related. If there is any when the radio is playing, it's extremely minimal. I tried cleaning the heads (which is when I noticed no hiss while running on accessory) and that didn't change anything.

Lots of articles talk about grounds, although they all seem to be about ignition noise. I checked the ones I could and they are all good.

Anyone have any ideas on the potential cause?

 

[Noobz347]

I think your unit needs to be either serviced or replaced.

 

[General karthief]

Does it hiss with the key in the 'on' position with the engine not running?
Listen for the sound while the fuel pump primes.
Also are the plug wires the resister type? Someone may have swapped in racing plug wires that make stereos unhappy.

 

[limp]

Also are the plug wires the resister type? Someone may have swapped in racing plug wires that make stereos unhappy.

Had that problem with my 4 track tape deck back in the day......

 

[bicknell]

I think I unintentionally lied. I didn't do a good test the first time, and didn't wait long enough.

After more research and comments like yours I went out an ran some more tests. First, I used one of those tape adapter things, like so you could hook up an external CD player, because several folks said if it was tape head noise that would eliminate it since the tape head noise comes from the tape sliding across the head.

I then tried accessory, on but not started, and started. The noise is present in all three states. It is a bit quieter in accessory and on but not started, starting the car seems to make it a bit louder. I recorded the sound to see if it provided anyone a clue. The click right before it starts is me turning the key to accessory. This is with the tape adapter in, volume at about 50%. Note the recording makes it sound louder than it is, I was holding the phone near the driver dash speaker to get a clean recording. A second level of "whoosh" comes in after a few seconds.

I don't detect any of this sound when tuned to an FM radio station. Seems to be unique to the cassette.

The recording: 1992-hiss

 

[bicknell]

Forgot about the plug wires. The plug wires are factory original. (Only 17k miles!)

 

[General karthief]

I'd say the noise is related to the head of the cassette player, try alcohol on a Qtip to clean it.

 

[bicknell]

I ran a cleaning cassette through it twice, no change in the sound.

 

[General karthief]

Not the same, clean it with alcohol

 

[bicknell]

Not the same, clean it with alcohol

Ok, understood. I think I'm out, so I'll pick up a bottle in the AM and clean it with a q-tip.

 

[bicknell]

Well, that did not go in the right direction.

I cleaned the head with a q-tip and alcohol. Very carefully and lightly.

Now I get no hiss. But I also get no playback. When I stick a tape in I just get dead air on both sides. I guess I'm going to have to pull it out and open the cover to see what's going on.

 

[General karthief]

Oh crap, well fixed the hissing
always used that method for tape deck hissing, maybe the belt came off or are they gear driven?
keep us posted please.

 

[bicknell]

I found a video where a guy replaces the light bulb in the radio on YouTube. The good news is these are super easy to open -- the top is literally taped on and then just lifts off. The tape mechanism is conveniently right on top. It should be easy to see if the head is out of place, there's a broken wire, etc. On the plus side I can also inspect the few large electrolytic capacitors for any signs that they are going bad.

I did order the "radio removal tool" off Amazon for $5. I probably won't get to pulling it out and looking until this weekend.

 

[bicknell]

I've been doing research all morning. I want to be sure I know what to expect before I pull the radio out, along with additional connections I should clean/check while I have it apart.

I can't find a mustang wiring diagram with the graphic equalizer in it. I did find one for a 1987 cougar, and the wires for the radio and amp match a mustang without the graphic equalizer so I think it's the same wiring. For anyone who finds this thread later the diagram is at https://www.fordforums.com/threads/1987-cougar-car-stereo-wiring.173609/

I know the radio removes by inserting the removal tool and pulling forward. From youtube videos looks like I should be able to side it out and disconnect the cables from the rear pretty easily. I can then open it and inspect the cassette mechanism.

I'm wondering if I should inspect the filter or the graphics equalizer for signs of bad capacitors while I am in there. I can't find any videos or walkthroughs that say how to remove the graphics equalizer or filters. Maybe it's obvious once the radio is out. If it's not, and someone knows the secret please let me know.

I also need to replace/repair the airbag module. From watching a video on that it seems like it may be easier to release the pins on the airbag module with the radio out. They seem to be unobtainium, although there's one place that might repair them. I did figure out some Mazdas used the exact same module, so searching for an MX-5 (I think 89-94) airbag module might work too. Someone else linked me this troubleshooting guide, I may go ahead while I have things apart and try and do all of the pinpoint tests: http://www.veryuseful.com/mustang/tech/airBag/airBag92.html#CODE51

 

[General karthief]

Whenever working with air bag wiring and modules disconnect the battery and wait 15-30 minutes for residual power to drain off.

 

[bicknell]

Update on the tape deck. I removed the stereo, which answered my first question. The graphics equalizer is bolted to the stereo and removes with it. The top has no screws, glue, or tape, it's just held on by friction. A gentle pry popped it off. A visual inspection shows no electrolytic capacitors with bulges, no signs of corrosion on the board. All the wire connections seem in place and firm.

I visually inspected the tape head, at least as well as I can. It's there, it looks right, and when I put a tape forward the mechanism moves it forward to engage the tape. I don't see anything too far off.

When playing forward I get a really faint version of the song, like I have to turn it up to 3/4 volume to get a whisper quiet version. When playing reverse I get nothing but dead air. I've included some pictures. I'm really not sure what to do next.

Seeing nothing obvious wrong, I'm completely unsure as to what to do next. I wonder if the tape head has gone "bad" in some way, and my cleaning it put it over the top. I have no idea what to do next, any pointers or suggestions from things I can try to a place I can send it to that can fix it would be appreciated.

 

[limp]

I ran a cleaning cassette through it twice, no change in the sound.

The kind with the sand paper strips on the tape??

 

[bicknell]

I hope there was no sand paper!

Through some more research I have 1) purchased on eBay a Ford Service manual for 1992 cassette decks, be here in a week. 2) Discovered the cassette portion of the radio is a Tanashin TN-707 mechanism. There is not a lot of information out there about them, but I did find a Blaupunkt manual with a full exploded parts diagram, and there are a couple for sale on e-Bay. Several threads say they are all interchangeable mechanically, but that when they sold them to people like ford they sometimes customized the connectors and/or left them off as the assembler wanted to solder the wires. So sometimes some soldering or connector work is necessary to swap the mechanism.

I think I'll see what the repair manual says to do first. Maybe the head tracking is just off and there's an adjustment procedure or something. But if that doesn't do it, I'll probably look to buy a TN-707 mechanism online somewhere and swap it. The mechanisms go for like $25 -- a replacement radio same as the one in the car seems to go for $800-$1000.

 

[Noobz347]

Update on the tape deck. I removed the stereo, which answered my first question. The graphics equalizer is bolted to the stereo and removes with it. The top has no screws, glue, or tape, it's just held on by friction. A gentle pry popped it off. A visual inspection shows no electrolytic capacitors with bulges, no signs of corrosion on the board. All the wire connections seem in place and firm.

I visually inspected the tape head, at least as well as I can. It's there, it looks right, and when I put a tape forward the mechanism moves it forward to engage the tape. I don't see anything too far off.

When playing forward I get a really faint version of the song, like I have to turn it up to 3/4 volume to get a whisper quiet version. When playing reverse I get nothing but dead air. I've included some pictures. I'm really not sure what to do next.

Seeing nothing obvious wrong, I'm completely unsure as to what to do next. I wonder if the tape head has gone "bad" in some way, and my cleaning it put it over the top. I have no idea what to do next, any pointers or suggestions from things I can try to a place I can send it to that can fix it would be appreciated.

Find an electronics/audio service center and send it in for repair before anything happens to it.

Maybe there's somebody closer to you but a place like this is what I had in mind:

https://www.sound-smith.com/services/classic-audio-electronic-repairs

The worst case is you pay shipping both ways to get an estimate and find out if it is repairable.

 

[bicknell]

Maybe there's somebody closer to you but a place like this is what I had in mind:

https://www.sound-smith.com/services/classic-audio-electronic-repairs

Thank you for the link. I've collected a list of 4 such places so far, I plan to make some calls and confirm they can repair tape deck issues with these if it comes to sending it out.