radio noise

[firelt226]

I need some help and or opinoins on a 91 convertible that I am looking at purchasing. It is equipped with the Deco Bose system with cd and cassete. The radio operates for a short time and begins to emit a high pitched noise when driving. If you turn it off and back on, it seems to be fine once again. This happens no matter if the radio is being used or a cd or cassette is being played. The owner has told me that he was told that it was a possible loose ground somewhere in the system. Does this sound right or can it be something else? Is this a big deal to fix? The car looks super is a 6 sd and has 39K miles. This is the only problem that I could find. Any help or thoughts are appreciated.
Thanks,
Jeff

[Radar]

You might have a case of failed speaker amplifiers. Each of the speakers have a built in dedicated amplifier deep inside the speaker housings. They are a bear to replace but are rebuildable. I think the cost is about $100 per speaker and there are four. A quick search on the net will bring up several places that do the rebuilds.

I too have trouble with my system. I plan to upgrade the car to a Pioneer receiver and elimate the Bose components. I can get the receiver+speakers+wiring harness from Crutchfield for less than the cost to repair the Bose. And it is a much better sounding system when done. I plan to keep the Bose parts in case I ever sell the car and the next Owner wants it all original. I also plan to documet all of the work in digital pictures so the next owner has a frame by frame record of what I did and how to undo it.

Good luck on buying that 91! Sounds like a great car. Don't let the radio scare you off. We all have trouble and get 'Hosed by the Bose'.

Regards,
Radar

[-=Jeff=-]

Originally posted by nyernga
here's one that might frighten you......it did me

No, the 1991 is in the sill, 5 minutes to remove, unlike the 84-89 door speaker removal.

[jeepie]

Sounds like one or more of your speaker amps are going bad. I had one of my rear
amps doing that, I replaced the capacitors on the amp board and that fixed it. The new caps were about $5. It is not always the caps that are the problem, but most of time it is, so if you or a friend is handy with a soldering iron you can fix them yourself. It is worth the $5 to try this fix first.

When replacing the caps in the amps...it is better to use 5% or 2%tolerance caps then the 20% that come stock. The tolerance rating is how much the value of the cap can swing dependent upon voltage and heat. The 2 main filter caps are 560uf (micro farads)...which means that at any time it can change from 448uf to 672uf. Quite a big swing...that is why I prefer 2% if not 5%. I also prefer to use military grade caps as the temp value goes up to 125°C versus 105°C for the stock ones.
And although the specs are tighter the parts are very close in price. It is worth it to replace the parts with a better grade.

And for testing purposes Radio Shack has several low cost Digital Multi-meters that will test caps. If the value is more then 15% off value replace it.

[firelt226]

Thank you all for your input.
Jeff