Recently one of the EL34's in my Marshall DSL stopped working, but when i replaced it with two different new tubes, none of them will light in that spot. If its an easy or common fix i would rather see if I can figure out the problem rather than paying an amp tech. Any and all help would be greatly appreciated!
Marshall tube issues
- Thread starter DannyStation
- Start date
TheWinterSnow
Den Mørke Natt
what do you mean light? Amber glow or blue glow, if the amber glow isn't there, it could be anything from, a blown current limiting resistor on the filament circuit, dry solder joint on the tub socket or even worse a blown tap on the primary transformer. If you are not getting the blue glow, most of the time it is a matter of a blown screen grid resistor, which can happen quite often in some amps depending on how much they cut corners in price.
best bet is to find a sheet for the tube socket layout, get a multimeter and make sure all the terminals on the socket are working, basic ground (cathode is electrically connected to ground), supply voltage at plate (anywhere from 350-500v depending on the amp) and near supply voltage at the screen (usually 20v less than plate), bias voltage on the control (-40 to -70v depending on plate current a how hot the amp is biased). If you are not experienced with electronics most people would rather take it in to a tech, but if you are comfortable working around a live amp and know electrical safety, then have a look around. Key word, electrical safety, if you know it, the voltages in the amp aren't lethal, just scare the fuck out of you when you feel a quick jolt, however touch something incorrectly (for example, having both hands in the amp at the same time), you might be saying goodbye.
Trevoire520
Member
Just take it to a tech man. If you don't know what you're doing then you might fuck the amp more than it already is.
