Pignose HummmmPOP

[Densman]

The opamp is a TL072cp. Its in a socket. Q1 is mpsu07 and Q2 is mpsu57.

[J M Fahey]

No other transistor? Amazing !!
I am a minimalist but these guys beat me big time.
Well, carefully (pamper the board) replace all them, meaning the TL072, 2955, 3055, and drivers.
Buy from a reputed dealer because there are fakes everywhere.
Use a good solder sucker, add solder wick if you wish, don't wiggle parts when solder is melting because it's easy to tear pads and tracks, specially on these old non-fiberglass PCBs.
This board is specially fragile because it was hand-drawn using black paper tape, and they used the thinnest one.
You have an 80% chance that the amp starts.
Anyway still use your series lamp, check for no DC on the output , still without a speaker, and if ok reconnect it.
Just in case also order some extra diodes and the ¿V08? Dip rectifier, we are talking cents here.

[phatt]

Guys a couple of points,

1/ Is that a *circuit-braker* on the top corner?
If so, Whatzit there for? Headscratch??

2/ The solder pad that CT's the 2 main Caps,, looks like it has let go.

cheers, Phil.

[J M Fahey]

You *can* test in circuit.
If they are dead shorts, nothing will hide that.
Download the 2955 and 3055 datasheets to know the pinout (and save them for future reference) All TO3 power transistors have the same pinout, so no problem there.
Those medium sized ones no, they vary wildly, so download their datasheets to check.
A short is a short.
Now if you expect an over 1000 value and get, say, 200 or 100 or  600 , not a short but not what you expect either, *then* you'll need to pull the transistor to discard that some other element isn't altering that.
Anyway they are 4 transistors in all, no big deal.
Use a good solder pump, finish cleaning with solder wick,  don't wiggle the transistors while the solder is hot because the pad unglues easily from the board and cracks.
From your picture I see the left transistor has its emitter connected directly to the negative rail, so it must be the 2N3055 (NPN) ; the right one its emitter to the positive rail, so it must be the 2N(MJ)2955, both collectors are grounded, as a curiosity the boards have big holes there so the (grounded) mounting screws touch nothing onboard, and the speaker "hot" wire probably comes out of the union of the big electrolytics; if I'm not mistaken it's the red wire that seems to touch the edge of the right electrolytic.. Unusual.
Resuming: measure all 4 transistors, if any shows a short, replace it at once, if in doubt pull it carefully to measure; worst case: replace all 4.
Turn the amp back on always using the series lamp.
Hi Phil: yes, it's a circuit breaker. I wish I had them cheap and easily available!!
I'm SICK of guys "repairing" a fuse with a nail, then saying "I always used the original fuse".
No, it won't protect a transistor, way slower than a fuse, but it protects the power transformer and, in the long run, your house.

[Densman]

I went ahead and replaced all the transistors, and it works! Thank you Mr. Fahey for all the help!  -Dennis