Marshall MB4410, with low volume gives no real volume,

Hi!
At this point, I would just take it to a tech rather than poke around in it. It sounds like the power section is the problem as you have guessed, but without the technical knowledge you'd be shooting in the dark. That particular amp is right on the line of being expensive enough that would be worth repairing, but you might do just as wel to check Ebay for another used one.
Good Luck!

I have same problem. i have this map. please help me to find the problem. if you can point the area in this map that problem is from that.

Sounds like a bad transmitter.

this is a electronic problem. there must be a capacitor/s in the output section that's swollen and will keep giving the same problem unless its replaced.

G.

More infornation is required to provide a real answer, but I can give you a few possibilities:

1) There is a problem within the feedback loop that is allowing some frequencies through. This will be more prevelant at higher volume levels.

2) If there is a tube pre-amp section, the tube can be "microphonic". This too is generally more likely at higher volume levels.

3) Defective components in the amp section. These may pass some DC voltages that will sound like distortion.

If you can, please experiment a little to try to find when the problem is most obvious. With more details about when the problem occurs may give us enough info to determine the cause. Otherwise a trip to a service shop that has access to test equipment will be required.

Dan

First make sure your guitar can't "hear" the amp as the sound can rattle the strings and have a form of feedback. Stand with your back toward the amp for example. If that doesn't help, take your guitar to the dealer and try it on another of the same type... see if it does the same. Also where you use it, make sure nothing is rattling in the area that can fool you as to how it sounds...

Test if it does it with the guitar cable unplugged from the amp. If it does, then it is time for servicing... If not, then you have a system grounding problem and the guitar cable is "leaking" signal into the amp. This can happen even if guitar is NOT connected.

Our bassplayer had the same problem with his mb4410. As it turned out, the fan was not working when the amp got hot. It did turn when cold - go figure! Swap the fan for a good quality (Pabst, Sunon) 80mm pc fan with 2-wire connection. Three or four wire fans will not work w/out modding. See your local pc guy and ask for an unregulated, silent 24/7 fans. He will know. Our bassplayer sold the P.O.S. while still in warranty. HTH.

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.

initially you want to think bad solder joint, but it think its a bad mosfet or rectifier or diode. it would be hard for an untrained person to identify your problem let alone an experienced tech. it may be time to move on to another amp. in my shop it would be at least 65 bucks for the repair. so where did the "heat"/energy go from that point and what parts were affected. there may be a domino affect. burn one part, not usually.
yostamplifier.com