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Fisher 500TX rebuild

I recapped the audio control board, and the preamplifier board today. I replaced the 1uf 35volt caps with 1uf 250v caps. I assume that’s okay?

I only have the FM board left to do, there’s a lot of capacitors on it. I’m really hoping the NTE transistors I ordered will work…we’ll find out Tuesday. 19D4D9AE-FAAA-4116-A260-C28B8D400595.jpeg
 
Test on DBT with old one's. If everything checks out ok, stick with the old ones for now. Keep the new ones safe for later if needed.
 
Went ahead and replaced the outputs. I read another post saying his outputs tested okay on the meter but were actually bad…

Popped in the diodes and driver transistors. I’ll power it up on the DBT soon. I hope it works
 

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I got it all back together and plugged into the DBT. I had the speaker selector off. I tried out the headphones first, sounded good but there was a hiss in the right channel that would get louder and louder and eventually “pop” followed by silence. Repeating cycle.

I turned the speaker selector switch on to my 8 ohm load, DBT still good,the headphones then sounded terrible. Distorted. I can tap on the heatsink and have audio inference and I can see the panel light flicker when this happens.

I tried to check the bias on both channels, they do not respond to the adjusting pots and read near 0 mV. I have it hooked up to a scope and I don’t really know how to interpret the waves, I know it’s not correct.

I feel pretty confident about the output transistors being in the correct place but someone please verify it.
 

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I’ve finally got it working again!!!

I tested the original diodes on the amp board and they were bad, I mistakenly replaced them with only a single diode (1n4001). I didn’t know I needed to use multiple ones.

I cannot thank Larry enough for all the help, I know I annoyed that man with all of my questions lol.

It’s been running my JBL L100s for hours now. I love this receiver! Oddly enough, before the audio and amp boards were recapped, it had a richer sound. Im wondering if all the new capacitors need to be broken in? I don’t have any experience with it.

It sounds good, I feel like it’s sounding better as the night goes on. Could be my ears adjusting. Great separation and control.

I would love to have a Tube fisher one day, but I’m more than happy with this one. Thanks to everyone here and all the threads on this website, I could not have done it without all these sources.

Cheers
 

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What you were hearing beforehand was worn out and out of spec caps, transistors and some resistors. Now that it has new (for the most part) parts, it'll sound closer to what it's supposed to sound like from factory.
 
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