M Jarve
Audio Geek and NGE Freak
A friend just picked up a Pioneer QX-949A receiver. Plugs it in and turns it on, and no sound, but lights up and what not.
So he brings it over to me, seeing as I have some knowledge of electronics, and can repair most things.
I plug it in, turn it on, and wait for the protection relay to kick out. It doesn't. I check the relay, and it tests fine. I bypass the relay, and get DC at the speaker jacks.
Okay, one or more bad output transistor(s). I take the grate off the power amps, and LO and BEHOLD! none of the output transistors match or are in pairs. Each output transistor is different.
From what I can tell, no one has been in there ever, or at least for some long time, as the dust on the screws internally was undisturbed.
So, if someone has one of these units (or the service manual for one) I would greatly appreciate knowing at least what the output transistors are.
Thank you!
So he brings it over to me, seeing as I have some knowledge of electronics, and can repair most things.
I plug it in, turn it on, and wait for the protection relay to kick out. It doesn't. I check the relay, and it tests fine. I bypass the relay, and get DC at the speaker jacks.
Okay, one or more bad output transistor(s). I take the grate off the power amps, and LO and BEHOLD! none of the output transistors match or are in pairs. Each output transistor is different.
From what I can tell, no one has been in there ever, or at least for some long time, as the dust on the screws internally was undisturbed.
So, if someone has one of these units (or the service manual for one) I would greatly appreciate knowing at least what the output transistors are.
Thank you!