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ivoh 18th December 2012 12:42 AM

Car amp repair and home amp conversion.
I have two dead pioneer gm-x862 amps. one was connected in reverse polarity, one was run without a heat sink and has no voltage output from the psu section. The one that was reversed works if i apply voltage to the +-38v section and every transistor in the psu section is shot. The one that was ran with no heatsink does not have output from the psu and when i connect the +-38v rails the - rail draws exessive current. Does that mean that one of the output transistors is dead? Im gonna take the easy route and try to convert them to run on ac power by using the transformer from a 5.1 channal sony receiver. Could i use the amps internal rectifiers or will i need external recitifers? Could i run them at higher voltages such as +- 45v as long as i dont exceed the 50v rating of the caps? thanks

ivoh 18th December 2012 08:26 PM

Well if anyone is interested i decided to just try it, the amp was junk anyway. Im uploading a youtube video if anyone is interested. Car amp on ac power - YouTube

Perry Babin 18th December 2012 09:23 PM

If you were going to try to get the amps working normally, I would be willing to help but I don't help with any mains powered equipment.

ivoh 18th December 2012 09:35 PM

Well i got one of the amps running on mains. If i can repair the other one for free to make it work normal i would. Theres is no output from the power supply, it does not draw excessive current. The light illuminates when remote is connected,but is very dimly lit without remote being connected. What else can i check? Thanks.

Perry Babin 18th December 2012 09:49 PM

Post the DC voltage on all 3 legs of Q660.

ivoh 18th December 2012 10:52 PM

1: 11.38v 2: 12.03v 3: 12.05 i measured those at R671 and R679 as i did not want to remove the pcb. Is that ok? Edit: with the remote terminal disconecected the voltages are 1:12.05v 2:2.1v 3:12.05v

Perry Babin 19th December 2012 01:02 PM

That looks OK.

What is the DC voltage on all 3 legs of Q914 and Q912?

ivoh 19th December 2012 03:56 PM

Q912 1:12.01v 2:12.05v 3:0v Q914 1:12.01v 2:12.05v 3:0v


Perry Babin 19th December 2012 04:03 PM

All of the power supply FETs have failed.

ivoh 19th December 2012 04:11 PM

ok, so would just putting in exact replacements fix it? or could something else also have failed? I have a couple of extra Irf3205, could i use two of them for testing purposes? Thanks Edit: also is ebay a good place to order replacements? or will they be fakes?

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