Xenon 1200.1 repair issue.

[audiophyle_247]

I have a Xenon 1200.1 that blew an output mosfet.

Replaced all 8 mosfets & the amp came right back to life and works great again, but there is one issue.

I have been running it with a regulated 12v power supply, and there is a whine very similar to engine noise. The while sweeps in freq very slowly, maybe a minute between each peak. It starts at a low freq whine & slowly climbs in freq, after about a minute it stops climbing & recedes back to the low freq at a similar rate. Low pass filter does not affect it at all, but moving my power wires around clearly affects the noise. I thought it could be the power supply, but this is the first amp it has ever done this with.

Anyone have ideas what could do this? The amps power supply works great, and I am thinking the issue has to be something located in the output area but everything looks good to me. Anyone encounter this problem before? I have yet to test it in a car.