Pin 3 is being driven high. Does it go back to pin 1 or pin 7 of the 8 pin IC (via resistors, possibly)?
If so, post the voltages on that IC also.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
What's the number on the 8 pin IC?
It may also go to a PNP transistor (likely small, black, shaped like the letter D).
If so, post the voltages on that IC also.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
What's the number on the 8 pin IC?
It may also go to a PNP transistor (likely small, black, shaped like the letter D).
Perry Babin said:
I removed it to check it and to see if the reading changed once it was out. According to the data sheet it is fine.
I wanted to check the diff to a working amp, and my sony had a reading of 19 Volts on the #2 pin on the output transistors.
And I thought about putting the one transistor in place in a good amp, but dont want to break a good amp.
Perry Babin said:
not sure, but im going to take this amp as a learner and take things off the board until i find a bad part(s).
If it was an expensive amp, I would continue.
Thanx for your help. (And will post if i find the problem).
I dont knw if u seen my other post on my source unit, the cd doesnt spin anymore, now I do want to fix that. - http://www.diyaudio.com/forums/showthread.php?s=&threadid=143348
I saw the other post but didn't have anything to offer to the discussion. If it doesn't spin, there could be a number of problems. I quit working on CD player mechanisms when the replacement cost of the entire head unit dropped to less than the price of the service manual and the replacement parts.
To check the outputs in the amp, use the form (link) on the following page (the one for BJTs).
http://www.bcae1.com/repairbasicsforbcae1/images/transistortestpage02.html
To check the outputs in the amp, use the form (link) on the following page (the one for BJTs).
http://www.bcae1.com/repairbasicsforbcae1/images/transistortestpage02.html
Perry Babin said:
ok tested again and the Z44's have .6 ohm
and the C2500 and BY028E have .5 ohm
my other amp (which i started to diagnose after giving up on the first one) that not working has one IRFZ34N out of 4 has a closed circuit even with a jumper. the other three read .56 Ohm.
does that mean the one is bad?
And should i put one of the good ones from the first amp in place or better to do all 4?
Perry Babin said:
ya i have the 4 Z44 out and the Z34 out.
and for all 7 of them the black PIN2 and red PIN 3
and pin 1 and 3 joined by wire.
---------------------------------------------------------------
the other C2500 and BY028E and F12C20A(2) are red PIN 2 and Black PIN 3.
and pin 1 and 3 joined by wire.
If you place the leads:
red > 2
Black > 3
Do you read an open circuit on the IRFZ34 and the Z44s? If so, they're OK.
The rectifiers appear to be OK. You don't need to short anything out to check those. As long as there is no short (0 ohms) between any of the legs (out of the board), they're likely OK.
The output transistors are the only heatsink mounted components that can cause the amp to go into protect. If they're OK, you likely have either a defective drive circuit for the outputs or a fault in the protection circuit.
red > 2
Black > 3
Do you read an open circuit on the IRFZ34 and the Z44s? If so, they're OK.
The rectifiers appear to be OK. You don't need to short anything out to check those. As long as there is no short (0 ohms) between any of the legs (out of the board), they're likely OK.
The output transistors are the only heatsink mounted components that can cause the amp to go into protect. If they're OK, you likely have either a defective drive circuit for the outputs or a fault in the protection circuit.
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