peavey pv500 power trip

[rj pv]

As I power up the pv500 channel B power trips. Found the transistors 70483180 and SAC 187 blown got replaced with MJ15025G and BTA16 600B but still trip. checked the driver board and found channel A transistor MPS6531 and 6534 blown but could not rectify the channel B tripping fault. Need some seniors guide please help me fix this amp.

PV260 stereo amp resistors near the transformer and main resistors heat up after a minute of operation. How to fit a small DC fan to cool the main supply section.

Lastly a very old 60s stereo amp with transistor AD149 Bx4 and diode BEL 0A73 Bx4 found defective replaced the transistors with AD149 because I could not get AD149-4 but sound is poor. Seniors please suggest me the equivalent of AD149 4 and diode BEL 0A73.
Thanks.

[Enzo]

Hi, welcome to the forum, I am glad you made it here.

A suggestion, threads are cheap, we prefer to have one amp per thread, it gets real confusing trying to work on three different amps in one thread, so make it three.

PV500:

Th B channel is bad? Is that the channel with the part numbers in the 200 series? I will assume so for now. So you replaced either Q200 or Q201 and the triac? Note there are two resistors associated with each transistor there. Check them all, and also important is R201 just to the left there, 180 ohms, check him for opens. Resistors often open when their transistor shorts.

If Q200 on the output board shorts, it is common for the driver, Q200 on the Driver board, to be damaged. And check its resistors too.

REcheck to make sure the new triac has not burnt itself out.

The triac is there to protect your speakers, not the amp. If the amp goes to DC on the output, the triac will turn on and short across the output. That will blow the breaker, and keep your speakers from catching fire. Seriously. having said that, when I work on a PV power amp that has blown, I remove the bad triac and leave it out until everything else is repaired, THEN I install a new triac.

If you don;t have one already, look up "light bulb limiter" and make one and use it. An extremely simple thing, but really prevents the amp from damaging itself during service.


Please work with NO speaker load until we have the amp stable.

Oh, and while we are at it, check the main rectifiers for the channel.


There are at least some things to start on.

If you don;t already have it, PV customer service will send you the schematic set if you ask them. Same for the 260.

Do you know which version your 260 is? Look on the serial number label and see if it mentions a year. WHich resistors are hot? The two 700 ohm 5 watt ones are normally hot, they drop the high voltage down to the 15v zeners. R141, 142.

And it might help to tell us make and model of your old stereo. But lets split up the threads first.