[23:05:39] Sharon Levit: hello! i have aproblem. iwll be glad if you can help me! so here is my problem: i bought a marshell 15 MG amp few days ago and this annoing buzzing problems. every time when i connecting my guitar or even without connecting anything there is a long buzz that not responding to anything even my ipod

https://www.youtube.com/watch?v=4ike6mtnECk
https://www.youtube.com/watch?v=be9oMgWXC3g
https://www.amazon.in/Marshall-MG15CFX-Guitar-Amps-Black/dp/B005ODB4QW
https://marshall.com/marshall-amps/products/amps/mg-gold/mg15fx

I once used uART & some latches to decode & hold the difference between "odd & even" midi program changes. Then used the output to switch a relay in a twin necked guitar to change between necks as it were in response to a midi pedal. Perhaps you could do something similar? Else get a Studiomaster MA-36 midi analyser & hack into it to use one piece of midi data (from across an LED?) to switch channels on your amp? Good Luck!

Hi, I have repaired loads of these kinds of amps. The first thing to check is if the input jack socket is still soldered to the circuit board properly. These have a tendency to break.
They all have a dual opamp and a 15 watt power amp chip. Invariably it is the power amp chip that fails IF it is an electronic fault. Both chips can be bought for a few pounds.
The variations, aux input, spring reverb and this, digital effects are extremely unlikely to cause this kind of failure.
At one time anyone with a screwdriver and a soldering iron could fix these, but in the days of health and safety, find someone who knows what they are doing.
It should take half an hour and about £3 worth of bits.
All the best, Chris the Fader.

Hi, Sounds like you have a bad cable to your amp. Try swapping out the cable. If that is not the problem, The pickup maybe bad.
Hope that helps.

Exercise your warranty IMMEDIATELY since you just bought it! If you bought this used, you LIKELY bought someone else's problem. The problem is likely in the digital effects area... probably a bad cable contact... but if under warranty DO NOT mess with it... return it for replacement or repair.

FixYa Subscribers have access to unlimited tech support, articles, and Experts!

First thing is to verify the MAIN power source is getting to the amp. It may not be the fault of the footswitch at all. Connectors and cables are the usual cause of these problems. Seating of connectors is a common problem...

For a test in troubleshooting, see if level from the headphone jack fades or not when this happens and get back to us.

Try this site:

http://www.youtube.com/watch?v=80d1HUa3W-U

After making sure your guitar cable is OK (they often cause the problem) check the inout jack on the amp. They often get broken by yanking cable sideways.