20 Most Recent Marshall Mg100dfx 100-Watt Combo Guitar Amplifier Questions & Answers

If you just bought it new, Marshall will replace any parts, or the store you got it from. If its second-hand I would have a look on ebay for parts.
The user guide can be found here...
http://www.marshallamps.com/product.asp?productCode=MG100DFX&pageType=DOWNLOADS

Good luck, its a sweet little amp!!!

I may be missing something but i cant see what amp you have? Is it a valve or solid state marshall?

Please, take it to a tech in your area, or look for a good one to ship it to. An 2007 amp is not old at all.

Hi,

This would only mean two things:
1. you have a bad capacitor in the circuit or the grounding on the circuit is broken and not filtering the obvious line noise from the circuit.

2. You have what is called, dirty power. That is when you have some kind of electrical device plugged that generates line noise which can be even a florescent light as they generate line noise.

Please take the following steps to narrow down the issue.

Take your setup and plug it in some where you know others can setup their rigs and it is using clean power. If, the humming goes away then it is dirty power where you originally setup.

If, it is still humming then you will need to take your equipment to a qualified marshall dealer have them look at it.

You'll find one here- Amp Archives Marshall Schematics Layouts MG Schematics

No this is not common problem.It must be internal circuit fault or setting fault.Did you tried reset,if not try reset ,but after the reset is complete.You will loose all your previous settings.In that case you will need to re select and set your settings/preset for this unit.The reset procedure is as follows:--- Restoring Settings - WARNING: ALL AMP & FOOTSWITCH SETTINGS WILL BE LOST To restore the unit to factory settings (see handbook rear cover) you must hold the Store switch while powering on the amplifier. The Clean/Crunch and OD lights will light orange. You can then release the Store switch.Resetting the amplifier will erase all user Channel presets and all user Foot controller settings, replacing them with the factory presets. ---------------- But if reset is not helping then the problem is either with the buttons,they are getting loose.Press the buttons bit hard tight,take care dont apply too much force.Then see.If that is not helping then internal button panel circuit needs to be checked,that is causing the problem.It can be repaired by local tv/radio repair tech.They can check and repair this circuit.------- -------------- This should help.Thanks.Helpmech.

This is the generic version of Viagra. Consult your physician before using.

It was Manufactured between 1981 - 1982 So it's about 33-34 years old...

It must go to a repair shop. There's always a reason that a fuse blows.

Buzzing could be normal for this amp, especially if you have the gain cranked way up (or the volume way up) see if the buzz goes away when you turn the gain/volume down. If not, there is a problem that needs to be properly diagnosed by the amp tech at your local music store. The crackling is also unfortunately rather normal for an amp that's a little older. Oxidation builds up inside the knobs and makes that noise as you turn them. If it only happens when you change settings I wouldn't worry about it, but if it gets bad, a tech guy can clean it out for you.

This looks like an overhaeting problem at fiirst glance. This shouldn't happen however. Have you had it long before it started failing? Doe it happen every time you play it, and also at low volume? If so, all I can think of is having it checked out by a technician.

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

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].

This is usually caused by oxidation in the potentiometer (fancy name for your volume control, also called a pot). The solution is to buy a small spray can of tuner cleaner, then unplug the amp and partially extract the electronics chassis from the case -- usually by removing screws in the top (but NOT usually the top handle screws), then gently sliding the chassis forward until you can easily see and reach behind your gain knob. You should see a squashed metal cylinder attached thru the faceplate to that knob -- that's the pot. It will probably have 3 wires attached -- don't worry: these never have voltages high enough to feel even when the amp is on. Either near where these wires are attached or elsewhere on that cylinder there should be one or more small holes. Using the small plastic tube that came with that spray can of tuner cleaner, spray a small amount of cleaner into the pot, then turn the gain knob from maximum to minimum and back several times. I usually do this by plugging the amp into a receptacle and moving the knob this way BEFORE using the spray, listening for the noises, then I spray it, manipulate the knob as described and hear the noise disappear. Unless you're confident about doing that, DON'T! Instead, slide the chassis back into the case and plug the amp in, then see if the noise is gone. If so, put in all the screws and you're done. If there's a noticeable improvement, but still some noise, move the knob bank and forth a few more times to see if that fixes it; if not, unplug the amp, slide the chassis out again and repeat the spraying procedure one time, then reassemble the amp and plug it in. If your problem is still not gone, you'll have to replace the pot. If you know how to solder WELL, you can order another volume pot thru a Marshall dealer or online, OR you can remove the pot and take it to a local electronics store where they can probably find an equivalent potentiometer at a lower price than the genuine Marshall part -- be sure to ask for one with "an audio taper" (a logarithmic change in resistance that corresponds to how audio amplifiers control sound). Good luck, and please post your results on this website.

Using a standard 1/4 inch stereo plug....Ground (sleeve) to tip for one switch and ground to ring for the other.

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