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My plexi blew the rectifier tube and fuse. No big deal, pulled the chassis out, everything look ok. Get a new tube and fuse...and blows again....

Any ideas what would take the rectifier tube out? I can understand the fuse going when the tube goes, but no idea why the rectifier goes.

Detailed notes...

Fine on standby
Blows immediately when taken off standby.
Rig has been stable for months....
VRM installed...

You need to divide and conquer. Remove tubes and try. If it blows, bypass VRM. If it's OK, it's the VRM.
you should probably make a light build current limiting device to save Your amp.



Essentially, it is (as the name implies) a single light bulb in series with one side of the AC line. It plugs into the AC outlet, and the equipment being tested is plugged into the limiter. If no short is present, the light will stay unlit or glow dimly. If a short is present somewhere in the unit, the bulb will glow brightly, as current is drawn through the filament. The higher the wattage rating of the bulb, the higher the current limiting capability. Use a 40 watt bulb.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Well, finally had a few minutes to pull the chassis and give it a quick test... tubes pulled..no problems.

So, I guess that means the VRM has a problem.... time to take a closer look at its componentry.

MOSFET may be shot. You can test the diode but they are usually pretty solid.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I'm thinking the same thing, although for the cost of a diode and a few resistors, I'll probably replace them all.

Bypass the VRM With tubes in. That will determine if it's VRM or not.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps