Fire in Marshall 2203

Motterpaul

Motterpaul

Tone is in the Ears
Messages
13,681
A reissue with a "Hum control" - this thing fried, don't know why yet.

Fire in Marshall2203

Hi I got an amp Marshall 2203-1 with effect card from a customer who has burned. As you can see at the attached pictures it is R31/32 in the filament system, and R17/18/20 in the feedback/cathode of the phase inverter tube, and R11 the cathode resistor at V2, the second valve in the preamp witch...
www.marshallforum.com www.marshallforum.com
 
JPH118

JPH118

Silver Supporting Member
Messages
4,586
I’ve seen a burned up hum control like that in a Marshall Astoria not long ago, couldn’t figure out what caused it, worked fine after replacing 100R resistors to ground.
 
J M Fahey

J M Fahey

Member
Messages
2,925
Motterpaul said:
A reissue with a "Hum control" - this thing fried, don't know why yet.

Fire in Marshall2203

Hi I got an amp Marshall 2203-1 with effect card from a customer who has burned. As you can see at the attached pictures it is R31/32 in the filament system, and R17/18/20 in the feedback/cathode of the phase inverter tube, and R11 the cathode resistor at V2, the second valve in the preamp witch...
www.marshallforum.com www.marshallforum.com
Click to expand...
Can´t see the schematic or pictures, upload them here.
 
Steppin' Wolfe

Steppin' Wolfe

Member
Messages
6,404
I have seen a burned hum(heater filament) balance control in a SF Twin reverb. There were no indications of why it burned up....at least by the time the amp got to me.
Feces occurum. Or...an engineer’s observance from the 1940s...anything that can go wrong will go wrong.
 
gldtp99

gldtp99

Member
Messages
4,305
Long ago a customer brought me a Fender SF Bassman 100 head that had toasted the Heater Supply including the Hum pot

After checking out the PT Heater Winding (seemed ok) I rewired the heater circuit without a hum pot but with a Artificial Center Tap consisting of two 2 watt/100 ohm resistors

The amp survived and went on to live a long life---- it was owned by the studio across the hall from my old shop and this head was used for recording/rehearsal/shows by many, many different players

They used it for both guitar and bass, as needed, and it was a true workhorse amplifier both before and after my repair of the incinerated Heater Circuit
 
Motterpaul

Motterpaul

Tone is in the Ears
Messages
13,681
J M Fahey said:
Can´t see the schematic or pictures, upload them here.
Click to expand...

Sorry, it is not my amp or pictures, I just linked to it because it's interesting. You can create an account over there to see the pictures. These links might work...




 
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