Hiwhat is the best way to connect my DigiTech RP10 to my Marshall MA100H Guitar Amplifier

I assume you've also made sure you're using a well sheilded intrument cable? If you're using a single coil pickup guitar like a Strat, you need to be sure you get the pickup cavity shielded. Past that it may be a bad tube in that gain stage.

Have you checked a different cable?. Also, when you plug in the unit, there should be a "pop" if everything is turned on. If there isn't, the connection is bad someplace.

faulty speaker cable?

I am very new here and don't know how to answer a question to a specific problem so I will write about the most common problems that I have had over the decades doing guitar amp repairs. If you find that your amp is extremely low in volume and then suddenly comes back to normal- check out the effects return [or power amp in] jack. Especially in Marshall amps-these corrode and your signal dies. If there is loud noise such as hissing and crackling with no guitar patch cord in the input jack- the input jack is likely at fault. They normally have switching contacts that ground part of the input circuit when the 1/4 inch male plug is disconnected. When this in is corroded or too weak to make normal contact, you can get these symptoms. If your amp is a solid state Marshall or Fender and there is a random buzzing sound with no guitar signal connected- hit the side of the amp and listen for the buzz to go away or become louder-if it does, this usually means that the connections are loose at the two large filter capacitors. In one or more Marshall amps, they use a filter circuit in the low voltage power supple for the preamp tubes. If you encounter a dead Marshall[the model escapes me now] remove the circuit board and resolder the four connections at the bottom of the bridge rectifier. If you have any other amplifier repair questions you can email me direct at [email protected].

Most common problem is broken input jack or soldering around it. Exercise your warranty pronto!

I haven't played or worked on a MG100HFX but I understand amp circuits very well. The behavior you are describing sounds to me like a bad capacitor in the Treble circuit. This is a problem that would require the skills of an experienced amp tech. If you are within your warranty period you might want to return it. If not, a good local repair shop should be able to diagnose the problem.

Good luck and keep rockin'!

Usually an aluminum heat sink is connected to the fan or near it and an amplifier chip/stick is on that. If that is what smoked, you need to take it in for replacement. Continued powering of this could damage the speaker.

There are a couple thumbnail sketches of the diagram at:

http://music-electronics-forum.com/t8790/

They are down about 3 an 6 of the blogs.

Well i know ive destroyed a guitar amp with a bass guitar before :-p this is why they make bass amps and guitar amps instead of just amps

First disconnect all inputs. If hum is still there, PROBABLY the filter capacitors have gone bad. Replacement is the cure.

IF there is no hum without any inpout cable connected, there is a ground loop and either the ground at the inout connector is broken, or your cables and guitar may have a problem.