Problem with a Fender Hot Rod Deluxe

thermionic

A bloke at work was asking if anybody could help with a problem with his amp, so I offered to see if I could help (although I won’t try any repairs).

The clean channel has been sounding distorted apparently, so I suggested he swapped the preamp valves (and PI) with a spare, and offered to lend him one of mine.

If it’s not this, any ideas what it might be? Although I’m likely to suggest he takes it to a tech if it’s not a ropey ECC83.

ICBM

If it's not a preamp valve (V1 or V3 - V2 only applies to the Drive channel) it's most likely to be either a dead power valve or a blown resistor - either a power valve screen resistor (which would normally indicate the valve has failed as well, and burned out the resistor) or a phase inverter plate resistor - or a bad solder joint associated with any of these parts.

An outside possibility is a failed filter cap - the last one, under the input jacks - although that tends to make the Drive channel 'motorboat' rather than affecting the clean channel.

DJH83004

+1 for IC's thoughts, especially the last filter cap, also a long shot but worth checking the LV +/- supply rails, although, the chips for the preamp out and reverb are not directly in the signal path (in parallel effectively), they can cause some strange effects to the signal when driven by half their supply.