Blaupunkt SC radio screech, wow!!!Anyone have this?

[Gunter]

1980 SC original Blaupunkt Cassett Radio with amplifier under the passenger floor board. Works fine for any function, then suddenly the most ear-piercing sound comes out of the speakers.
A quick shut-off and turn back on, it plays fine for a while, then the same thing happens. Sometimes not for an hour, sometimes within five minutes. What gives? Anyone else had this experience? What type Blaupunkt was put into these years?

[Bill Verburg]

I had that happen w/ a Bose system in an early '90s Audi V8Q. They were known for having issues w/ their amplifiers No cur that I knoe of other than R&R

[SpeedracerIndy]

My dad's Carrera has this problem. He has the original Blaupunkt casset with the amp/equilizer under the passenger seat. It happens when it is on for a long time. We don't know what causes it though. We have just attributed it to the stellar Porsche sound system.

[Gunter]

Stellar? good point. If it didn't have the automatic seek feature, which I like, I would get another one. Rats!

[bell]

the feedback you're hearing can be caused by a couple different things......
1.....does the screech come from ALL the speakers?
2......is there any corrosion near the amp? or maybe got wet?

loud feedback is usually associated to the preamp signal, check the cables for any chafing.
but if the ground for the amp is corroded/loose the amp would ground itself through the din cord.......which can freak electronics out.

the second thing that can cause this is a grounded out speaker......pop out a door speaker and see if they're wet.
if you can unplug the speaker wires at the amp you can use a multimeter to check the wires for continuity to ground, then also check their impedance (ohms) they should read between 3-4 ohms if it reads below 2 ohms then the voice coil in the speaker is either corroded (from moisture) or burned, a damaged speaker can wreck havok on amps.

i'd start with the multimeter and check for a grounded speaker wire, if you don't disconnect it from the amp it WILL show ground......with it unhooked it should read nothing.

[Gunter]

Thanks. The frustrating thing is that it only happens occasionally, hard to trace. It seems to come from all the speakers, but, I'll disconnect the rear ones and see. You are right, some tracing and inspecting of the wires is in order. Cheers.

[Install425]

I second Bell it is most likely a bad speaker or grounded speaker. I would disconnect speaker wires from amp and check with meter. Check continuity to ground, you should not have a ground readering at all, if you do then either the speaker or wiring is the problem.