SOURCE: My marshall jcm2000 dsl50 will not power itself
Check standby power supply,it stays on all the time main power is off and is subject to damage from transits from power company.Bad switch?
SOURCE: JCM 2000 TSL 601 MARSHALL AMP TURNS ON NO SOUND TUBES DONT LIGHT
If the tubes are not lighting, either the fuse has blown or the power transformer might have an issue.
Be vvery careful as there are lethal voltages present in these.
If the fuse blew, replace it and try just once as there could be other problems and more damage could be done.
SOURCE: Marshall MG50 DFX, the volume knob OD channel crackles
Either the control is damaged (happens if they get hit) or it is possible the circuit board it is mounted on has broken solder OR worse, a crack near the control. The unit will require servicing. Parts are readily available.
SOURCE: the valves on my Marshall TSL 122 are getting to
Probably the bias is set wrong... Please note that when installing MATCHED pair tubes, the tube pairs usually go at opposite ends of the strings, that is one on either side of the center of a set of four.
SOURCE: Hey, the clean channel on my Marshall 250dfx Combo
The switching is done electronically by an analog gate chip. On IC9, check if the signal on pin 8 changes with switching between clean and OD... This is the actual signal that changes the gate. If you don't see a change there of say 5 volts, then the problem is in the circuits that drive this gate. If the signal is there, then the problem is in the clean channel audio op amps or the components around them. Let me know the results of the test.
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A common problem with these amps is a failure of the BR1 bridge rectifier that feeds the heater voltage to the power and preamp tubes. This repair should be done by a professional as there are hazardous voltages inside the amp chassis. After the repair is completed add a muffin fan to keep things cooler.
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