I have a Sunn Stage Lead, best sounding SS amp I have!

Ok, relative to the red/yellow wire (P6)
red (P5) - 53.6VAC
red/wh (P7) - 53.5 VAC
brn (P8) - 0 VAC
brn/wh (P9) - 22.4 VAC

Well whatever shorted did cause quite a show, I am not surprised. I'll take a look at that tranny. The overvoltages with an open winding doesn't make much sense to me either.

Voltages between P8 (brn) and P9 (brn/wh) is 0VAC.  P8 to ground is 0VAC.
P9 to ground is 22.4VAC.
A = red wire
B = red/yellow
C = red/white
D = brown
E = brown/white

A has continuity with all but D
B has continuity with all but D
C has continuity with all but D
D has no continuity with all
E has continuity with all but D

Transformer wires are correct. No voltage on P8 or P9 to ground unplugged.
No doubled wires on posts.
Only 5 secondary wires.
I have to take board back out to disable fan rectifier, will try to get to later tonight. Fan does come on as soon as amp is turned on.
The floating piece of metal was found on D112 of the fan circuit just a FYI.

P5 (TP1) - 54VAC    52.9VAC
P6 - 0V                    0VAC
P7 (TP2) - 54VAC     51.9VAC

TP3 - +72VDC         +70VDC
TP4 - -72VDC           -70VDC

P8 (TP5) - 23VAC       43.2VAC measured this 3 times
P9 (TP6) - 23VAC        22.4VAC

TP7 - +30VDC            +56.2VDC
TP8 - -30VDC              -55.9VDC  measured also 3 times

0VDC between P8 and P9 unplugged.

R161 is 11.2 ohms

QuoteDoes this mean +70V at TP4 and -70V at TP5?
How can you have +70V at TP4 which is a negative point?
Please confirm.

Sorry I mixed those up...-70 at TP4 and +70 at TP5 like it should be. I'll recheck what you have requested.

Quotewhat is the mains voltage where you are?

110 volts USA

QuoteWhere are you placing the negative/blackmultimeter probe?

To ground at the chassis AC ground

Bad transformer?

I didn't remove any of the board wires, but doublechecked anyway, all wiring is correct per schematic and board labeling. I measure +70/-70 at TP4 and 5. Resistance check from TP5 to ground is continuity.

Voltage regs:
U101
Pin 1 - +55.9V
Pin 2 - 0
Pin 3 - 0

U102
Pin 1 - 0
Pin 2 - -56V
Pin 3 - 0

Power to voltage regs but nothing on the output side.
I will check the other test points per Mr. Fahey

That's why I changed all the rectifier diodes in case it was AC coming down the path, but I'll admit I'm still learning these things. I'll get some voltages posted soon.

Its literally blowing them apart. I hit the rafters in my garage with a piece of flying debris. I'll take out the regulators and get some numbers. I have them in the right spot btw. I did pull out a chunk of metal, a welded chassis nut for the case that had broken off. Who knows what damage that thing did in there.

I am working on a Fender Bassman 400 ss bass head, its is blowing voltage regulators to bits. I replaced the 7815 and 7915 regulators and it blew 'em again. I have now replaced them once more along with all the diodes nearby. Instead of lifting one leg to test each I just went ahead and replaced all D100-111. Q102 was also blown and replaced. Ready to start it up on the limiter, anything else I should check beforehand?

Thanks for clearing that up, I figured since it was 29 years old (it is an 84) that they were bad. I will get voltages today and go from there.

I have a Peavey M2600 power amp on the bench right now with low output. Guessing the main caps are shot. They are 5000uf 55v. Having trouble finding these but I do have some 6800uf 80v will those be okay? Thanks.