I still have no sound on my 90 stock stereo. The main unit in the center dash has been gone over and repaired. It has power. I pulled the tuner from under the dash. It has been gone over and tested fine. So now it looks like I am headed to the speakers. Is there a fuse somewhere for the speakers I am not seeing. The radio fuse checks out. If one of the speakers amps is removed, would that kill all the other sound?

 

I have a complete stock system. Head unit and CDM box were refurbished by DR. Don. All new speakers and rebuilt amps were installed. It is possible that all your amps are bad but not likely. If Head unit and CDM box are OK then you should at least be able to play a CD or tape and get some sound. If your system was done by a pro check with them to see how to go next. I am no expert.

Good Luck! Keep us posted.........

 

thanks for the reply

I am going to reinstall everything tonight. Both units were done by a local Dr. type. If I can't figure it out I will take the car in on Monday, but that means $$$$$

 

If this is a Bose system and all of the speakers are dead, remove the hush panel above the driver side knee.

You may also want to remove the seat. Lay on your back and look up towards the instrument panel.

There are two relays between the steering column and the console. The one closest to the console is the Bose relay for the Speakers. You may have a empty relay socket next to it. That's for the Fuel pump relay used by the ZR1.

The two other relays toward the driver side door are for the Starter Motor and AC compressor.
The relays are on sockets and are all the same so you can pull the Bose relay and put the AC compressor relay in it's place to see if cures the no sound problem.

The Bose relay uses the CTSY fuse. If your courtesy lights work, the fuse is good.

The other fuse used by the relay is the Radio fuse. If the Head unit has power, the Radio fuse is good.

Yes you can disconnect each speaker and the other speakers should still work.

 

Thanks for the reply. Is the relay upstream or downstream of the fuses? What I mean is the fuses are both good and the courtesy lights work. Would that mean the relay is good? Or can the relay be bad and the lights still work?

 

The fuses are up stream of the Bose Relay.
If the fuses are good, the relay is most likely bad.

The relay supplies 12 volts for the amps. inside of each speaker. If no audio gets to the speaker from the tuner, you should still hear a little bit of static / background noise from each speaker.

When the Control Head is turned on, it sends a signal to the Receiver box which applies 12 volts from the radio fuse to the Pink wire of the Bose Relay. The relay energizes and applies 12 volts from the Orange wire which comes from the CTSY fuse. The Orange wire passes 12 volts thru the relay contacts to the Pink/Black wire which turns into a Pink wire at the speaker. This provides 12 volts to each speaker amplifier module

If you remove the speaker grill on one of the rear speakers, look at the electrical plug at the speaker.
With the radio on you should measure 12 volts on the Pink wire, the Black wire is ground. If you don't measure 12 volts, the Bose relay is bad.

 

Thank you so much. I will try this tomorrow morning.

Glenn

 

Tried the above and still no sound whatsoever. Not even a hiss. I got under the steering column and found the relays. The relay plug closest to console was not there, while the plug closest to the steering column had a relay in it. Traded that relay with the relay for A/C. Still no sound.

Went to the speakers and measured the voltage. For the front passenger spearker, with the radio on, has 12 volts on the pink wire with a black stripe. The light green wire has 5 volts and the dark green wire has 3.5 volts. Everything goes to 0 when the radio is off.

Is there anything else I can try?

Glenn

 

Seriously though, one thing you might try, just for the hell of it, is to give the bose amplifiers a SEPERATE signal, to see if they at least operate and output something. At least thats what I would try next, for sanity reasons, and, its pretty easy to do. In fact, you could very well use a walkman to do this, by hacking off the wires to the headphones, and putting the positive and negative of the signal from the walkman to the inputs of the bose amp, and see if it at least amplifies. You could use a home stereo preamp with similar results as well. If you have neither a walkman or a home preamplifier, a $7 fm radio and cheapie hedphones from walmart will work too.


just trying to help! Thats an easy test you can do without costing much money, and without pulling the CDX unit

snoopdan

 

Can you explain the history of your problem. Was the system working properly and something happened?

Just to clarify, the manual shows 12 volts for the rear amps. is a Pink wire. The manual shows the 12 volts for the front amps. as a Pink/Black wire so your test does indicate you have 12 volts to the speaker amps. so the Bose speaker relay must be good.

For the Front Passenger side Speaker/Amp.

The Light Green wire is an audio input to the speaker amp. from the Tuner box. The Dark Green wire is the audio common signal input to the speaker amp. from the Tuner box. The Front speakers share a common audio signal wire and the two Rear speakers also share a common audio signal wire. The audio signal uses a floating ground. I measured the voltage on mine with the radio playing and measured 5 volts DC on both the Dark Green and Light Green wires.

Do you have the correct CDM box? Is there a sticker with the part number 16087100 on the Tuner box ?

If you have the correct CDM/Tuner box and you know it works, my guess is all of the speaker amps are bad.

I can tell you when I was trouble shooting a buzzing noise on all of my speakers, I wanted to make sure it wasn't the power source since it is common to all of the amps/speakers. To isolate the amp. I unpluged the plug at the passenger side front speaker. Using a car battery, I applied 12 volts to the orange wire and ground to the black wire and you could hear a faint back ground noise from the speaker. In your case you do have 12 volts at the speaker amp. but no back ground noise, so I can only conclude the amps. or speakers are bad.

 

OK the mystery is solved.
I took your advice and put a signal from a radio into a powered speaker. No sound, no hiss, no nothing.

I started pulling speaker enclosures. The speakers themselves looked fine. Took the car and the speaker enclosures to the local Dr. Don equivalent. We tested all the amps and every one of them were bad. What are the odds of all 4 four of them being bad at once? Then we started to disassemble and every one of them had a visible burned area on them.

So now I need to get them refurbished. OUCH!

Well at least the mystery is solved. I hope. Thanks for the above advice and I will update this when I get them back next week.

Glenn

 

Wow, that sucks.

Thats pretty friggen odd that all four are crispy. Id be interested in finding what stage of the circuit failed, the preamp or at the switching FET's. That would tell you alot...ok....that would tell me alot about what might of happened.

You never mentioned, but did it ever work?? Something like that must of had some sort of violent occourance...Usually something squeels or at least pops when somehting like that happens. Really odd..

Bummer.

snoopdan

 

The history of how this happened is unknown to me. I bought the car last summer and it didn't work then. No sound. The main unit, the part that you see, didn't work properly. It made a clicking sound like it had a broken CD in it. I had that unit overhauled and a new CD mechanism that would read CDRs installed. After I reinstalled and still no sound I pulled the tuner, but is was OK.

The guy working on my radio said he has heard of this happening if and alternator on a car has a meltdown, but that doesn't seem to have happened to it in the past.

Again,
I really appreciate everyone's insight.

Glenn

 

Yeah, I kinda guessed that it happened before you onwed it. The alternator idea is waaay far fetched...there are way more sensative electronics than a 40 dollar bose amplifier in a vette. Sounds like some moron at the dealership removed an aftermarket head unit and put an original one back in. Lucky you eh?

I bet you a dollar someone wired the 12+ lead into the preamp inputs...and BANG! Bye bye transisitors.

oh well. Hope ya get it straight.


snoopdan

 

Snoopdan

If you hook the 12 volt to the wrong wire on one speaker, could it fry all the others? I do know enough history of the car to know the original radio was never removed. I got it from a private party that was the original owner - a guys wife who never worked on it. However, the front left speaker had been repaired at some point. Maybe when they were messing with that one?

Glenn

 

When you start reversing voltages in DC circuits, all kinds of crazy things can happen, but mostly smoke Probably was done when they were messing with the replacment. Thats still pretty odd though.

sorry man...


snoopdan

 

Well I think I have recovered to being able to look back and say I have learned something about my car from this. Plus I am interested to hear what it will sound like. I have yet to have tunes in this thing.
I should get them back by next week.