1999 MK IV B channel switching and LED issue

[Commander Coo1]

I have owned my 99 MKIV widebody combo for about 4 months, and I really enjoy playing it! for the past few months the loop LED has been fading in and out (no effect to the loop function). Then, Last night while I was playing the amp switched itself to R2. I figured my external switchin was the issue (not an FU3) so I removed the jacks, and used the rotary selector knob to change channels. OK, seems normal. I plug my switching jacks in 1 by 1 as i test functionality, and the problem is gone. I play for another 30 or so seconds and it goes back to R2. I unplug everything, switching jacks, FX loop, run guitar straight into amp, now the rotary switch on the back is not functioning either. slowly over the course of 25-30 seconds the amp changes from R2 to LD with a slow fade of the LEDs, then there is a strange woosh sound.

Did I have an LDR failure? any way to check? any other possible causes? other troubleshooting? Mesa says it will likely be $150-$250 to repair from my description...

Thanks,
James

 

[Commander Coo1]

Looks like somehow the FX loop Autoassign was switched to R2. Not sure why this would cause switching issues but it did. I switched to the middle off possition and the problem went away. Does anyone else's behave like this?

 

[Big Block]

I had a IVB years ago that went haywire in the switching dept. Ended up being a short in the foot switch that fried an LDR. Was around $100 to fix back in 2008.