QSC PWM IC

[lowell]

Right on. Well, I'm treating this as a learning experience at this point. I ordered the transformers and will have an update when I get back home.

[lowell]

Well i damaged T1 upon removal so I couldnt test it. I installed a new transformer. The amp turns on now but clicks off every 5 seconds or so but immediately clicks back on. I THINK the mains relay is switching on and off and that's the source of the audio clicking noise. I dont think this relay plays any part in shutting down the amp however...all it does is short out the thermistor after powering on.

I metered my 16v supply and while the amp is on the supply reads 17v. It goes away at each CLICK but immediately returns. So, progress. Please suggest what might be causing it to shutdown this way.

There is 3.8vdc on Pin9 of U14. Seems this is shutting it down? How do I locate which of the many sources is causing this?

[nickb]

Well i damaged T1 upon removal so I couldnt test it. I installed a new transformer. The amp turns on now but clicks off every 5 seconds or so but immediately clicks back on. I THINK the mains relay is switching on and off and that's the source of the audio clicking noise. I dont think this relay plays any part in shutting down the amp however...all it does is short out the thermistor after powering on.

I metered my 16v supply and while the amp is on the supply reads 17v. It goes away at each CLICK but immediately returns. So, progress. Please suggest what might be causing it to shutdown this way.

There is 3.8vdc on Pin9 of U14. Seems this is shutting it down? How do I locate which of the many sources is causing this?

Are you having fun yet? That replacement board is looking like a bargain now!

The sources are
U13 inputs +ve should be > -ve for normal operation
U13:1 - undervoltage lockout
U13:2,4 - main switcher overcurrent trip (likely culprit?)
U13:3 - power off shutdown
U15: Amplifier DC offset (the other likely culprit?)
U17: Thermal shutdown

[lowell]

Kinda having fun actually. Ok I'll peruse those.

[nickb]

Well, you are certainly learning lot's of new stuff and that's worth plenty. I think that is what you are really in it for anyway.