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See photo: in the end it turns out that some banana plugs are just working with a little extra... I ordered some of the BFA-style connectors mentioned earlier in this thread and will report back... Some other growing pains w/ the PL400. I had some crackling/popping from the right channel which...

Good advice. I will check bias in both units when filter caps get here. On an unrelated note, I spent the afternoon replacing filter caps and installing Don's fantastic speaker protection relay in the Phase Linear 400 I have had sitting for 6 months. Very happy with how it all turned out except...

Those look nice! How long are they? Mine measure about 18mm. The banana plugs I always use bottom out too early (photo attached)...

I will try these pins! Project update: transistors arrived today. It was not easy to get in there, but I got the transistor replaced on the first try and now the amp is working perfectly! I biased both sides and all is well. I am waiting for new filter capacitors from DigiKey. Recommend...

I don't, it's just what I've got lying around.

I'll try to ferret them out! While I wait for parts... I am struggling with the binding posts. The holes are too narrow for 12 gauge wire and they don't seem to work w/ standard banana plugs or have room for most spade plugs. What's a good spade connector for this old style binding post?

Neat! I'm running music right now through PL300S2 #2 for the moment because the way I jumped the bias transistor was stable but temporary (I didn't trust putting the cover back on). I will report back next week on adventures in transistor replacement. I was lucky to find the parts I needed one...

Embarrassed myself! I found some NOS 2N3403 that should arrive in a week or so.

Now we are having fun! It looks like GE 2N3414 are not that easy to find but NTE289A is listed an equivalent part in a few cross-reference databases. I'm thinking I will order a handful of those and replace both bias transistors and replace filter caps w/ Cornell CGS153U075V5L.

Ads are the worst. Reverse conduction test on bad channel is identical to forward conduction test. Reverse conduction test on good channel is very different. Meter reads open leads between B and E. Sounds consistent w/ a short in the bad channel bias transistor?

I understand from your documentation in an earlier post that this is an NPN transistor, so with the amp discharged and unplugged, I set my DMM to diode test mode, placed the positive lead on B and then touched the negative lead to C and E. C: .761, no beep E: .179, beep On the good channel...

Jumpering C to E yields a bias voltage of 0.145V, there is no longer any humming, and the DBT extinguishes after a few moments as expected, rather than staying dimly lit during operation. Does this suggest that the bias transistor is faulty, i.e. not switching properly with correct control...

Thought so. So my plan of attack will be to jumper the C to E from the traces on the reverse side so that I can steer well clear of the power transistor lugs.

Well, the "lost or stolen" one showed up today without warning. I brought it up on DBT and and measured DC offset less than 5 mV each side. Happily playing music now. The broken one that started this thread I didn't originally bring up on a DBT because it was sold as tested/working. This...

Sage advice from all here, thank you. Learning is part of the hobby for me, but I will also gladly take it to someone local if anyone can recommend a good technician in the NYC area.

LOL I bought two of these on eBay and one is a toaster oven and the other was just declared lost or stolen by FedEx. No scans in seven days.

Yes, that's a photo of the failing channel. I looked at the solder joints on the back side and they all appear equally crappy. I'd be afraid to try to reflow them all and burn out a component w/ my heavy hand. I can try this jumper concept but I want to make sure I have the right transistor...

The bias voltage on the working side is dead on 0.35V. The bias voltage on the overheating side was 0.8V and increased to 1.1V when turning the bias pot w/ a chopstick. Changing the pot across the entire range could not lower the potential below 0.8V. Now I guess the questions I have are: is...

I inspected the board for damage and the only thing I see is that the ceramic capacitor w/ one insulated leg is looking like it's starting to crumble and has a shorter insulated leg than the other channel. Transformer solidly bolted down. The bias trim pot looks to be the white/yellow plastic...

Thanks for this concrete info. I can at least check those DC voltages as a start. Is audible hum from the amp but not the outputs consistent w/ a bias adjustment issue or does that sound like something more sinister?