bradwilcox

Stock Bose Delta system in 1989 200, working fine. Car goes into shop for other stuff. While there, they deprive of power too long and radio goes into safe mode. I unlock.

Driver door speaker makes horrible screech as soon as the radio is turned on i.e. even before the normal music sound would have otherwise "arrived" at the speaker. If that makes sense -- maybe it's a Bose thing: there is a momentary lag when working properly (usually a thud followed by a lag then the good sound will come forth). Also the horrible sound is a set volume, immediately at power-on, and does not change when I twist the volume ****, i.e. I can't make the squeal itself louder. It's not a sound of static, by the way, it's like a pig squeal.

So I test the system with a replacement head unit that I have, that I don't use otherwise because its face is shot. Issue persists, so it's not the head unit. OK, so I think the speaker or its amp is shot. Odd coincidence but whatever. I remove the speaker assembly from door in anticipation of replacing it.

Works for a moment. Now horrible sound comes out of one of the rears!

If I restart car, the system will work OK each restart but only a small minority of the time. Even if it comes up OK, the squeal will begin again anyway, after a minute.

The fuse in the back of the radio is OK. Dual antennae connections are OK. Squeal happens with or without them, anyway.

The squeal, whether it is immediate or delayed-start, will totally overwhelm and destroy any perceptible music or speech, i.e. if I turn up the volume, the radio signal is not still there and making it to the speakers but being shouted over by the squeal; there seemingly is no legitimate sound going to the speakers anymore at that point.

Ideas? Must stay stock.

V8BOB

Sounds like you need all the speakers rebuilt with new capacitors. Had mine done some years ago, I'll see if I can find who did it. I think it was a friend of someone on the forum. The parts are not that expensive it's just labor intensive.

Bob

toml99

Not sure if that was me, but my good friend Jim rebuilt 6 sets of amps for others on the Audifans V8 list maybe 10 yrs ago. I bought boxes of 100 of the 3-4? different electrolytic capacitors and had people mail me the amps and Jim charged $75 I think to do all 4 as at the time internet guys were charging $75/each which is absurd. I just looked and have no reciept for that capacitor order and all that info is on a hardrive that I can't access till I get a new to me mac as my last one died a few months ago and am functioning on girlfriends old pc laptop. Any electronic repair(think guitar amp guys/stereo people) can do this easy. Hardest part is heatgunning off the plastic goo sealant on the big ones....The caps are the things that look like tiny beer cans on board. If you have good eyesight and a small soldering iron and a cheap solder sucker you can do this. As I recall there's 9 caps per amp so thats 18 solder joints/amp. Your symptoms are classic cap failure and once one goes, can have domino effect on rest....Most likely had nothing to do with mechanic, just happened. Doubt recall is still valid, but all the cars(minus V8 for some stupid reason) had recall. I have 3 sets of amps all with bad caps....known problem. When you redo all 4, you will be blown away by how good it sounds. I'm older so have 1000's of cassette tapes which I totally enjoy only in the Lago car(with 4 rebuilt amps). If I can dig up the caps specs, will post, but like I said, an electronic repair guy can easily replace all electrolytic caps on all boards and your noise will go away....Tom

toml99

Oh, and if you pull the amps and find the caps leaked and rotted out a board, I got you covered. If you want to install a new non bose unit, need to upgrade wire to speakers as Bose's entire idea was to send low voltage signal to speaker, then amplify at speaker limiting line loss(their unique and theoretically/personally superior system)....the 18-20ga wire going to the doors won't like a new 100 watt Alpine going thru that skinny wire....BTDT.

V8BOB

YES YES YES!!!!!!
Tom took care of this for me years ago and the speakers are still producing excellent sound.

Thanks again Tom

bradwilcox

OK fellas, update:

even though the coincidence level is astonishing, both front and rear amps were indeed failed. But why in the world would they have worked prior to the head unit going into safe mode? Oh well, I guess stranger things happen?

The rear amp is as of now dead for unknown diagnosis, but we can assume it's probably the capacitors. The front, however, is melted on one quarter of the entire board. Must've suffered some kind of crazy power surge, related to the head unit or not.

toml99

What most likely happened(instead of power surge) is the caps leaked out the fluid which rots/shorts out board and can start fires which is what the ancient recall was all about...See if this is in the vicinity of the large ones(green?). Some of those fires happened when the cars were quite new, so ALL of those amps originally contained defective capacitors unless they got recalled or rebuilt. The 3 cars I parted had no leakage, but only one had the stereo headunit and pretty sure that is the set of amps I labled "good" as it worked. I need to dig out box of amps and see what I have. If you plan to keep the car, you're gonna want to recapacitor all 4....will sound better than new