power 8004

[megael9]

Im working with this unit. here is what im getting
35v at each of the 4 speaker out connectors, I measure
all the out put mosfet, and no short.
thanks in advance

[LAJ]

loss of the opposite supply rail. You should have both + and - 35 out of your power supply rails.
Or, you could have a shorted component upstream of the outputs.
Since it appears to be on both speaker outputs, I'd guess that you lost a power supply rail.
Do not connect any load (speaker or otherwise) to your outputs until you resolve the DC problem.

[Perry Babin]

Do you have both positive and negative rail voltage?

Do you have both positive and negative regulated voltage on the op-amps?

Can you post a photo of the inside of the amp. The partial model number could be several amps.

[megael9]

back to this amp, I have + - 36 volts out
of the rectifiers, no output mosfet is getting
hot. there are 2 set of 4 contacts for the
speakers, the 2 inner contacs are ground, and
the 2 outer contats are speaker +. all the outer
contact have + 35. there are 11 8pins chips
part # tlo72c. any sugestion?

[Perry Babin]

Can you post a photo of the inside of the amp. The partial model number could be several amps.

[LAJ]

Could be a defective TL072 op amp. Do you have any DC on the outputs of the op amps (pins 1 & 7 on each chip). If the input op amp was delivered a hot signal, it could short resulting in the op amp output going to the supply rail ( either + or - 15V).

[megael9]

here is the reading for all the op amp ic's
pin
1= .8v
2= .8v
3= .8v
4= -10v
5= .8v
6= .8v
7= .8v
8= 31v

[Perry Babin]

The positive regulator appears to have failed. 31v is far too high.

[megael9]

some one put the wromg reg,
instead of a lm317 they use
a lm337. know after I replaced
the reg for the right one, Im
getting 12v at pin 8 of the op amps,
but Im still getting 35v at the speakers
output.

[megael9]

here is an image.