Hello to y all, so two Marshalls came to me as a payment, both of them were making a intermitent hum/noise that when you bump the top of the amp either go away or get worst, short story is i already fix in both cases the problem by cleaning the amp, and also re soldering all the pcb, and cleaning the fans, BUT... one of the two amps did not turn on the LED on power and LED when you change to channel two, i thought i would get rid of that trouble by the re soldering but it didn’t, i notice that also the fx and reverb just wont work.
Things to know
The amp sounds and work properly.
Already tried with and without footswitch
Problem was already there when i re solder the amp so no chance that resolder was the problem also i do took my time doing it because i hate to come back for little mistakes.
I do not know the background of the amp, only thing i notice was someone already been inside before.
The problem does not affect anything else but that, as if the fx and leds are just bypassed.
The question where should i look first?i have to repeat that i do not have to much knowledge on solid state amps, already fixed and modded a couple of tube amps in the past, and some months ago i asked over here for a frontman which did repair too, any pointers would be helpful, thanks a lot
Things to know
The amp sounds and work properly.
Already tried with and without footswitch
Problem was already there when i re solder the amp so no chance that resolder was the problem also i do took my time doing it because i hate to come back for little mistakes.
I do not know the background of the amp, only thing i notice was someone already been inside before.
The problem does not affect anything else but that, as if the fx and leds are just bypassed.
The question where should i look first?i have to repeat that i do not have to much knowledge on solid state amps, already fixed and modded a couple of tube amps in the past, and some months ago i asked over here for a frontman which did repair too, any pointers would be helpful, thanks a lot
Did you check for voltage at the diode pins to start with something? BTW - if I was you and really want to use these, I would replace the tiny heatsink with a proper one.
Hey, no man didn’t know where to check first, so do i measure any diode? Or where specifically do i start taking the measurements? I don’t intend to use them already have some people interested in them, so i just want to fix them to be working as they were stock, and sell em, thanks for the reply I’ll be waiting for instructions, thanks
Thanks for the pointer and reminder, Im getting 4.94 vdc, sorry if i double check or ask to many questions add to all of these that english is not my first lenguage, thanks I’ll be waiting for next instruction
That voltage seems a bit high to me for a typical led.
It suggests the led may be open circuit.
I'd be tempted to unsolder one leg and test the led with your multimeter (diode function).
It suggests the led may be open circuit.
I'd be tempted to unsolder one leg and test the led with your multimeter (diode function).
Just get a bunch of same type leds and solder a new one. If it doesn`t fix it, check the current limiting resistor on the led, although it should be fine as you can use any wattage value there...If ll fine, trace where your voltage gets lost.
These amps are known very well in the guitar community as horribly built with very low quality components and the only reason to get bad sound from one of them is because you have plugged in a guitar...
These amps are known very well in the guitar community as horribly built with very low quality components and the only reason to get bad sound from one of them is because you have plugged in a guitar...
no reverb: remove reverb spring and inpect internal wires, more often than not one of them is broken by some shock during transport.