Master volume is scratchy on MG100FX

Try this first with the piano off, run the control from stop to stop rapidly several times. The object is to clean off any dust deposits and shine the contacts inside the pot. If the pot is not damaged beyond repair, then this should fix it.

Open the box and try to spray a cleaning/lubricating solution inside the volume pot mechanism like Deoxit D5, you can also spray a little of it on the output connectors where you plugin your cable that runs to the amp. If that doesn't solve your problem you have to replace the volume potentiometer. The machine I have had similar issues and I was lucky to have a pot close in size and resistance value as the original which in my case was broken, so I just replaced it. Good luck!

Just spray a few shots but you have to take the top cover apart, then take out 3 philips screws in the pots module, take off caps and then you should be able to give'em a good cleaning spray shots.

The pot needs to be cleaned. Get a spraty can of DeOxit 5. Spray it into the track and move the slider up and down a number of times. If that doesn't fix it, replace the slide pot.

What did you spray it with? I hope NOT Deoxit or Blue shower as those wreck the pots by removing the lube.

Use CRC226 available in the electrical dept at Home Depot. Use the plastic tube by bending it so it can spray upward into the slot where the leads that solder into the board go into the metal can.

Spray a little in and work the pot... then try a little more and see if it improves the situation. If it does, treat all the pots the same. ALSO look for broken solder where the pot wires solder to the circuit board..

If the volume pot is scratchy noisy, FIRST try squirting a bit of CRC226 into the pot. CRC226 is available at Home Depot in the electrical department. There are other CRC products there so be sure to get the 226 type. About $2.75 a can.

The product is also good to use in slide pots on mixers. Use sparingly, it doesn't take much. For rotary pots you often can use the spout to spray into the slot where the terminals go into the pot.

That should be a 320K pot. <br /> <br /> Here's a link to the schematic. <br /> <a href="http://www.ampix.org/albums/userpics/10003/MArshall_MG100DFX.pdf">http://www.ampix.org/albums/userpics/10003/MArshall_MG100DFX.pdf</a> <br />

Try cleaning your volume potentiomenter with contact cleaner (they come in spray can's), the scratchy sound is audible when you turn your volume control on, the contacts inside your potentiometer accumulated dust or some other particles.

Here is where you can get the service manual:http://celedoniaorgan.netfirms.com/cosco/nfoscomm/catalog/product_info.php?products_id=1021&osCsid=3eaaa99d6bfceeaaf9b844687ba58d55 Since the problem is with the foot pedal note and the keyboard note I would suspect that there is a problem with the tone generation circuit for that note. You might try cleaning the key contacts on both for that note first to see if that works. The volume pedal probably just needs the volume pot cleaned with contact cleaner spray. I hope this helps. Let me know if it does.

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.