I've just come into possession of a Peavey Triple X. It's been on the bench today getting the power tubes biased up and I've noticed the plate voltage is >500VDC. See attached image file of measurements collected.
I double checked the rear switch next to the IEC14 is set to 230-240V.
The power supply components look all good, and the amp sounds good and is functioning fine.
The DC output of the bridge rectifier is slightly higher than the calculation I've made. Not sure why.
As far as I understand, the high plate voltage is a problem as it's above the max specified for the 6L6GC tubes. It seems as if the secondary windings from the transformer are too hot for the power supply, but I don't work on amps all that much. Hoping for some advice on how to proceed.