I have the mono AM/FM radio (model 91BFP1) in my Chevelle, and I noticed recently that my speaker "pops" when turning the radio on. The sound still comes out normal when I turn-up the volume.

I did get suspicious on this and checked the output of the radio with my digital voltmeter. The speaker was still hooked up for the load.

Upon turn-on and the volume still down, the output has about 2.0Vdc without any sound. When I turn-up the radio, the sound comes-out as normal, but I'm concerned about the DC riding on the output.

Seems like the DC offset isn't adjusted, or is it something else starting to die, like the output transistor, or more that likely a capacitor.

Any ideas???

Thanks!!

You should notice the speaker cone move to one side and stay there if 2.0 vDC is on it at all times. The easiest solution is to add a BAC (big ass capacitor) in series with the speaker. This will block the DC. Too small of a cap (in uF) and the bass will be weaker.

I did a little more digging (electro-motive.com) and found-out that the output should have about 1.5Vdc on the output. The speaker should be pushed away from the magnet, if the polarity is correct.

Wierd.......

Thanks 70GS455......