A1020 - lots of clicking, then no sound

Awesome, I've found the TO-220 insulating pads and mounting bushings and added them to the order along with the trim pots. Any advice on the best heat sink paste? Also, any recommendations on replacements for the 2 large 22,000uf filter caps? They are currently testing at 17,000uf which isn't terrible but it's not ideal...
 
Did you order mica or silpads? If silpads you don't need paste. Also, can you post a Mouser link for the bushings? I couldn't find them when I looked, had to order them locally (and most likely spent more than from Mouser).

Cheers,
James
 
Thanks again Avionic. Order has been placed for everything. Fingers crossed this does the trick - or at least gets me a good step closer...
 
Sigh....all the transistors have been replaced, and the trim pots, but I can't get a stable idle current. Each time I turn it on the current is completely different! Any ideas?
 
Both channels ? Does it ever stabilize? Say after 15-30 minutes ?
 
Sorry I wasn't very clear, when you turn the amp on both channels stabilize at an incorrect voltage. You can then adjust the trim pots to get the right voltage, and it stays at the right voltage, but when you turn the amp off and back on the idle current is completely different and way off what it should be.
 
Vintage John said:
Sorry I wasn't very clear, when you turn the amp on both channels stabilize at an incorrect voltage. You can then adjust the trim pots to get the right voltage, and it stays at the right voltage, but when you turn the amp off and back on the idle current is completely different and way off what it should be.
Click to expand...
It's a SS amp. Leave it on 24/7.
 
Vintage John said:
Sorry I wasn't very clear, when you turn the amp on both channels stabilize at an incorrect voltage. You can then adjust the trim pots to get the right voltage, and it stays at the right voltage, but when you turn the amp off and back on the idle current is completely different and way off what it should be.
Click to expand...
Vintage John said:
but when you turn the amp off and back on the idle current is completely different and way off what it should be.
Click to expand...
Have you tried letting the amplifiers stabilize for 15-20 minutes. Then check if the idle settings are close to what you initially set before you powered it down?
 
avionic said:
Have you tried letting the amplifiers stabilize for 15-20 minutes. Then check if the idle settings are close to what you initially set before you powered it down?
Click to expand...
It my take a while for the amplifier to thermally stabilize. Bias/idle current is definitely temperature sensitive.
 
Bit of an update. Both channels work, but as soon as I turn up the volume it seems the speaker protection kicks in and it shorts (DBT bulb goes bright). I thought it might be something dodgy in the protection circuit so I removed all the transistors and checked them but they're all fine. Any ideas on what I should check next?
 
Did you check/re-solder all of the solder connections in the power supply and protection areas?
When you replaced the transistors in the bad channel did you check/replace the diodes & zener diodes and fusible resistors in the channel as Avionic suggested?
Have you measured for DC on the speaker connections?

On the 1020 that I worked on when the one channel blew there were several fusible resistors that were blown. You need to check all of them in that channel, especially the ones on the driver boards.

Cheers,
James
 
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