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After that bit of discouraging news, I dug deeper into the origin of the DC voltage. I traced the signal path back on the schematic and I'm finding some DC voltage between C207 and 209 on the left side, and C208 and 210 on the right. The "outsides" on each capacitor read 0VDC, but on the leg...

The two blown outputs have been replaced (driver boards are still out). Out-of-tolerance mylars have been replaced and all diodes removed for testing were reinstalled. On the DBT In class AB I get: -12.25V on the Left and -5.5V on the Right. In class A, this changes to -7.5V and -3.75V...

I think we're definitely looking at a DC voltage issue. Have to find where that -5 and -13VDC is coming from.

One flameproof that was replaced and a couple of output transistors and one driver transistor. I haven't been able to get the NOS driver transistor from Bdent because of some website issue, so the little boards have been removed for now. However, I believe the protect circuit is working...

I believe all the ones I pulled are marked "K" Would you replace just those outside the 10% tolerance or those beyond 5% since 5% tolerance films are widely available now?

Just for the heck of it, I pulled the green polyester caps. Most of them (70%ish) fall very close to their rated value, but there are a few further away. What would you consider the cutoff for replacement? 8%-10% above rated value or more? Anyhow, nothing major found that would indicate the...

I noticed a few of the green-top caps (maybe film or mylar?) look a little bulged. Is this how some of them typically look, or should I pull and test them?

Did a bit more testing today. Pulled and tested almost all the diodes in the unit. Standard diodes all tested fine both in forward and reverse-biased modes (up to 19ish volts in reverse). 5.95V Zener diodes all seemed alright with open points averaging 5.92V and topping out at 6.2V across...

Yes, that is where I'm measuring the negative voltage. The voltage is the same at both ends.

I tested all of them out of circuit. Measured good.

Where would you suggest I begin testing in the power supply?

Caveats: "driver boards" are uninstalled because whenever they were in, the fuse blew. Also, two of the outputs are disconnected because they were blown and I haven't gotten replacements yet. That aside, I reinstalled everything I took out. I also replaced one burnt flameproof resistor on the...

All copper screws and buses (except the +/- 16V buses) show continuity with the center tap. Any other grounds I should be checking?

And those ground buses/copper chassis screws should be grounded to the center tap of the transformer correct?

Since I had little to no idea as to where I should start testing, I've been going with throwing everything at the wall and seeing what sticks. So far I've pulled all the transistors on the main board including the JFETs, the large grey resistors in the center and near the relay, as well as all...

Following your suggestions, last night I pulled and tested all components on those small boards. One side had a failed SA driver transistor (shorted C-E) and the other side had a failed 2SA970. All the 1.2k resistors tested fine, but they obviously got hot on one of the boards, so I replaced...

A while back I posted with some questions regarding an A1020 I had purchased and restored from chernobyl status. Following that, I did some updates involving recapping, bypassing the send/receive jacks, and replacing the front LEDs (except the power light as I heard it was used as a voltage...

As a few may remember, I recently did a repair on an A-1020 with shorted outputs and the typical fallout. I've been using it for some time now, but as I haven't had my cooling fans available, I haven't yet used class A. Today I decided to try it just for a song or two. After about one minute...

I've ordered the transistors and all new lytic caps. Since I'm hoping this will be my main amp for a good while I would really like to go all the way with the updates I do. Should I consider replacing the mylar/pp caps with new film? I'm open to any upgrades suggested.

After replacing the drivers and outputs as well as the burnt resistors, we have a relay click and sound. I used the MJE transistors because I had already ordered them and they came with the outputs. After some listening on my main speakers, I'm not disappointed at all. I'm still more than...

I just pulled the outputs' emitter resistors to test; they all test fine, but I noticed the plastic looks a little odd on the bottom. Could this be from melting/damage or just manufacturing? Would it be considered odd that they're alright given that the output transistors failed?

Ok, I'll plan to order those and some 470 Ohm resistors for testing. What wattage are the flameproof green resistors? Are they 1/4W like standard resistors in the amp?

I went with MJE15033G and MJE15032G as replacements for the drivers; I couldn't find the others on mouser/digikey and I had already placed the order. Hopefully those will be suitable? Should all of those resistors be checked even if they show no signs of stress/heat?

I apologize for the bit of poor photography. I've ordered the transistors because nothing else appears amiss. When I go to install them, is there any point in only doing a bit at a time? E.g. replace everything but the outputs, then connect and test on DBT, so if there's anything still wrong...

I tested a few more transistors on each side of the problem this morning...everything I tested seems fine. Everything on Function Boards 4 and 5 has been tested. Outputs are dead on the odd-numbered channel. I attached a photo as you suggested showing the schematic and what I've tested...