Fisher RS-717 with water damage. Guy wants it fixed for nostalgia's sake...

John

On Friday, July 20, 2018 at 9:10:32 PM UTC-5, John-Del wrote:
Fisher RS-717 with water damage. Guy wants it fixed for nostalgia's sake...

John

Nobody has it on all the freebie sites I know. Perhaps SAMS ?

Or would you rather elaborate on the problem and maybe do it without the print ?

It had water damage. Screeching, squawking, full volume with the vol at zero, or no sound at all. I had to remove several connectors and other parts to wash the board in a parts washer (my sink). After reassembly, it works fine except the FM is low volume on both channels. AM is normal volume as are the other inputs. I think there's a problem around the function select IC (if not the IC itself).

I'm going to see if the customer uses the FM. If so, I'll have to do this backwards using datasheets. A schematic is almost like cheating...

On Friday, July 20, 2018 at 10:10:32 PM UTC-4, John-Del wrote:
Fisher RS-717 with water damage. Guy wants it fixed for nostalgia's sake...

John

John
What happens if you look at the discriminator output? What if you switch to FM mono? Maybe there is a circuit right after that output that "preamplifies the demodulated signal before it gets to the common audio circuits? Lenny

On Wednesday, July 25, 2018 at 4:01:31 PM UTC-4, wrote:
On Friday, July 20, 2018 at 10:10:32 PM UTC-4, John-Del wrote:
Fisher RS-717 with water damage. Guy wants it fixed for nostalgia's sake...

John

John
What happens if you look at the discriminator output? What if you switch to FM mono? Maybe there is a circuit right after that output that "preamplifies the demodulated signal before it gets to the common audio circuits? Lenny



No change in mono mode Len.

In any case, it doesn't matter. Customer doesn't use FM so he picked it up yesterday.