Victrola multi-player - No audio

[kokopelli75]

Hello!

My mother has a Victrola Navigator player that stopped functioning after a storm. I checked out what I could - all player functions appear to work, but there is no audio output in either the speakers or the headphone jack. I suspect (with my limited knowledge) that the amplifier part of the device is toast. Photo of the suspected board is attached. There's separate boards for front display, record player, etc. This board has a section for power regulation and a section for amp. There's a UTC7266 7+7W dual bridge amplifier IC and a CSC2314F sound processor IC on the board. Visually, nothing is obvious. No caps look bad or bulging, no cooked resistors. Power regulators are providing voltages in range. Any thoughts on what I can check to identify the bad component(s)? Unfortunately, I'm limited to a multi-meter for test equipment.

Thanks!

[stj]

get a datasheet for the amplifier,
then check it's getting the right supply voltage.
if it is then try injecting hum into the input pins to test it.

[kokopelli75]

Hi, thanks for the suggestion, makes sense to bypass the processor to see if the amp is working. I previously did the first part, both vcc pins are at the correct voltage. What's the best way to introduce hum without blowing anything up?

[kokopelli75]

Ok, I injected some noise on right and left inputs, and heard it through the speakers. I guess that means the amp IC is working. Perhaps the sound processor is toast?

[stj]

i see some op-amps in the picture, the LM324, says UTC but it's an LM
LM4558 - again marked UTC,
the 4066 is a digital switch - probably selecting the inputs.
i cant see the number on the other 8pin chip or the larger one with pencil on it

try messing with the opamps

[stj]

btw, if it was EMP then the 4066 is pretty vulnerable.

[kokopelli75]

Appreciate your feedback. Will poke around some more. In the meantime, here's a better picture of the whole board with some notes.

By the way, I was just testing with the radio function, and I can just barely hear some output on the speakers. Changing the volume had no affect. Playing a CD, nothing at all was audible.

[kokopelli75]

Interestingly, I measured 0V at all of the UTC324 Vcc pins (4). 🤔