Fuse blew on Fender DRRI 65 - why would that be?

ICBM

They can be tricky. It's often easier to undo the baffle first and push it forward a bit, which will allow the chassis to drop down slightly and not jam on the top of the cabinet.

Philtre

Moving the baffle forward worked.

By the internal fuse I see a pair of terminals CP1 (purple) and CP2 (white with black stripe).

By the tremolo intensity control I see another pair of terminals CP7 (white) and CP8 (black)

I'm going to swap CP2 and CP8...wish me luck!

Philtre

Done.

The trickiest part was getting the bloody chassis out. Loosening the cabinet baffle and pushing it forward a tad helped. Had to extract one of the wires out of the cable tie so it would reach to the terminal.

Powered up and all is working fine.

Not sure if it's me but the amp seems a bit quieter?

One other question - do the power valves need re-biasing now on 240v?

Anyway, @ICBM thanks for your help. I guess the amp should run better at 240v now?

ICBM

Yes, it should be marginally quieter, both as in background noise and maximum output volume. You could possibly rebias a fraction hotter to compensate but it’s not really necessary.

Everything in the amp will run slightly cooler and more conservatively, which should help with longevity as well as possibly stopping this arcing issue.

Philtre

@ICBM really thanks a lot for your continued help in this, you have the patience of a saint!

Power valves measured about 22mA so I upped them a tad to around 24mA. (Using a TAD BiasMaster)