#1
So I was just playing my Marshall avt-20 with my headphones and it just died... its got one power tube which I switched out with another I have and no luck. The speaker just gives a LOUD hum that is constant with a little crackling. Absolutely no effect from any input or any of the pots (volume gain etc)
Anybody got any ideas?
#2
Are you using the right tube?
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#4
I noticed the bridge rectifier is heating up dramatically. Like it shot up above 50 deg C in about a minute. Does this mean it died?
Seriously has anyone ever blown a diode rectifier with headphones before?!?!
#5
Does the AVT have a headphone socket..? Very rare for any sort of valve amp to have a headphone port..
#6
Quote by dandadog
Does the AVT have a headphone socket..? Very rare for any sort of valve amp to have a headphone port..

It does but the only ones iv heard of is the Fender Princeton recording amp and maybe a few Marshall's.
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Last edited by teamhex at May 17, 2010,
#7
Quote by dandadog
Does the AVT have a headphone socket..? Very rare for any sort of valve amp to have a headphone port..


It's got a SS power amp.

If it's got a loud hum and is drawing excessive current (= heat in power supply) I'd be checking for problems in the power amp. The output coupling capacitor maybe gone.
If you don't know what you're doing then it's time to go to a competent tech.
#8
Quote by PaoloJM
It's got a SS power amp.

If it's got a loud hum and is drawing excessive current (= heat in power supply) I'd be checking for problems in the power amp. The output coupling capacitor maybe gone.
If you don't know what you're doing then it's time to go to a competent tech.



Even so. Preamp valves can still make it dodgy for a headphone socket AFAIK.
#9
You might have lost a filter cap. that loud humming that you cant control with any of the amp's knobs sounds to me just like mains hum from an unfiltered DC supply.
#10
I found two little zener diodes that look like they went through a fire so I am gonna try to replace those.
PS this isnt an expensive amp so I feel stupid trying to bring it to someone to repair. Its a great amp for the price but id rather get a new practice amp then take it to get repaired. And i do fairly know what im doing with amps just looking for any ideas.