How can I repair my Bass Amp?

marshall mb4210. bass amp, the classic channel is a lot quieter than the modern channel, any idea's

phillip
May 2013

you can get into the parts and see if there is a wire out and if so weld it back in

dz
April 2010

i've got a marshall 3520 amp.the problem is i turned it on and after a couple minutes of playing the bass sound will stop coming out of the speaker .its quiet for a couple minutes and than it will start playing again .please what could it be

thanx

Tom
January 2010

hi, i have just been through a nightmare repairing my trace combo and had all sorts of problems so heres a few pointers...

if you have got the power light on as you say, then it may be that the amp is fine but your speakers blown. if there is an extension out socket for an additional speaker get hold of a correct resistance bass cab (prob 8 ohm) and plug it in. if it works then it as your speaker, fane do a budget 15 inch driver 300 watt for about forty quid including delivery from blue arran, a lower wattage one may be even cheaper. Alternatively if theres a head phone jack see if the phones work, again if they do it would suggest the speaker.

if theres no sound, from theext cab or the headphones replace all the fuses that look blown. i found that i had fuses in the power amp stage and in the power connector. if there black take em to radio shack and ask for the same ones, they should be about 30-40pence.

worst case scenario, when you have the head ut of the combo and the fuses are ok and still nothing, then look for any signs of carbonscoring where somthing has burnt out. most likely the transformer for the power supply, the big round thing which has usually got creammy coloured tape wrapped round it, that can be expensive, or look at the power amp stage to see if any of the fets have burnt, they are the little three legged lumps prob near the heat sink. i just replace mine, cost 47 quid for 4.

sorry if thats a bit garbled.

best of luck

Neil

neil
November 2008

Hi Toby
I have just fixed mine. Take the 4 screws out of the back plate the one with the power connector then lever the plate off you will find two fuses 3.5amp each both of mine had blown. I replaced these, amp was fine.
Good luck Peter

Peter
October 2008