been a while since ive asked for any help and i try not to these day as i want to be able to work it out for myself-but!
i have one here i just cant work out, both speaker outputs are -26v
when i got the amp both output transistors were blown on the right channel and fuses along with them as you woudl expect, so they were replaced.
I have since checked and tested all other transistors in the output Q401 through to Q418, both channels and all are ok.
the power sections on both rails have the correct outputs.
i have -26v on all 4 output transistor bases and emitters
i also have -26v on the feedback resistors R429 and R430, in fact pretty much -26v all over the place so i dont have a good starting place.
ive been trying to work out what what genericaly could affect both channels the same
any ideas?
i have one here i just cant work out, both speaker outputs are -26v
when i got the amp both output transistors were blown on the right channel and fuses along with them as you woudl expect, so they were replaced.
I have since checked and tested all other transistors in the output Q401 through to Q418, both channels and all are ok.
the power sections on both rails have the correct outputs.
i have -26v on all 4 output transistor bases and emitters
i also have -26v on the feedback resistors R429 and R430, in fact pretty much -26v all over the place so i dont have a good starting place.
ive been trying to work out what what genericaly could affect both channels the same
any ideas?
You need to check that those voltages are reaching the output stage at their destinations. Measure at these exact locations. It is possible a resistor is open.
Be sure to use the bulb while working on this.
And if they are present and correct then it gets more interesting
Be sure to use the bulb while working on this.
And if they are present and correct then it gets more interesting
Attachments
Well there is your fault
If they are at -26v and yet you measure the correct positive values (as per your diagram in post #5) at the power supply then there has to be an open circuit.
They are the same point... yes Take a step back and recheck on the power supply and then on those points again.
If they are at -26v and yet you measure the correct positive values (as per your diagram in post #5) at the power supply then there has to be an open circuit.
They are the same point... yes Take a step back and recheck on the power supply and then on those points again.
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