Gibson g30a

[nosaj]

I have two replacement transistors MJE205 and TIP42g. Like a dummy I didn't take pictures of the way it was before removing so now I don't know which one goes where. 3 wires for each transistor
-

What voltage should I get at Vc and V in the power amp section?

off the bridge its showing 34v +- Schem shows 48 Still should get some sound I'd imagine even if voltage is low.

On the left side of one of the pics are 3 wires
white -1.15v
brown -33.76
Green 18.50

Right side
white 1.01
brown +34.12
green 19.60

I just don't know which wires goto B C or E

Thanks for any help

nosaj

G10,G20,G30-1.pdf

[Jazz P Bass]

Well, you have me totally confused
Exactly which transistors are you attempting to replace?
The schematic has a "Q" designation on each & every transistor.
Please advise which ones.

[52 Bill]

Well, you have me totally confused
Exactly which transistors are you attempting to replace?
The schematic has a "Q" designation on each & every transistor.
Please advise which ones.

Don't be confused, those schematics are not for this amp. The amp has a bipolar power supply, the schematics don't.

[Jazz P Bass]

So this is the correct schematic?
Again, which ones are we talking about.
It appears the OP 'may' be talking about the output transistors, although the part numbers do not jibe with the schematic.
(I refuse to guess)

[52 Bill]

So this is the correct schematic?
Again, which ones are we talking about.
It appears the OP 'may' be talking about the output transistors, although the part numbers do not jibe with the schematic.
(I refuse to guess)

Yes, I think that that is the correct schematic, I had hoped that nosaj would find it for himself. It really wasn't that hard to find. Hopefully with it he will figure out which transistor is which and how they wire in the circuit.

The original TIP33B and TIP34B are no longer available, so I assume that the new ones are his replacements. I can't find any versions of the data sheets that show a TO-220 version of these, but the schematic appears to show them drawn that way.

Maybe the OP can tell us which style case the originals came in.