DSL 401 - Dead?

Fez

Power valves glowing nicely but no sound.
Fuses OK slight hum from transformer as normal.
So my first thought is pre amp tube gone. Any other ideas on anything else it could be?

Kebabkid

M @Fez - you're close enough to take it to Henk in Horsham. He'll sort it or at least tell you what's wrong.

All the best

rico

Bridge rectifier? Have you had it seen to previously?

ICBM

The preamp valve filament rectifier has desoldered itself. This is 'the DSL401 fault'.

You should see the power valves and the phase inverter still glowing, and the other preamp valves dead.

You can fix it permanently by fitting the heatsink that Marshall saved a few pence by not doing, and resoldering it.

It's also worth fitting a couple of rubber grommets around the upper rear chassis bolts to increase the cooling gap slightly.

Fez

Sounds like a job for Henk then. He sorted my other Marshall out a couple of years back. Never had a problem with the 401 before it's had nothing done to it not even new power valves and and I have had it about 10 years. Prob get a re-valve while were at it.

rico

Fez said:

Sounds like a job for Henk then. He sorted my other Marshall out a couple of years back. Never had a problem with the 401 before it's had nothing done to it not even new power valves and and I have had it about 10 years. Prob get a re-valve while were at it.

I only got new power valves on mine recently after 11 years and it sounds so much better

jimification

Fez said:

Sounds like a job for Henk then. He sorted my other Marshall out a couple of years back. Never had a problem with the 401 before it's had nothing done to it not even new power valves and and I have had it about 10 years. Prob get a re-valve while were at it.

Good plan - Henk is a top bloke!

Fez

The 401 is back in the room after Henks tender ministrations. It have blown a valve and taken a resistor out as well. Henk also repaired my Fender Champ II which had a faulty switch and he replaced the volume pot so it now has a smooth rise in volume rather than off and loud.