Marshall MG10 cd guitar amp picks up radio frequency?

"Overdrive Channel: high frequency noise as the gain and volume are increased."

This is the expected result, you are experiencing feedback. Try turning the "Contour" knob all the way to the left and turn down the tone knob on your guitar.

Hello,

I've seen a bunch of Marshall Combos and a very common failure comes from broken resistor legs at pre-amp and power amp modules insides, they are the low-value/2-3W rated and the soldered legs broke so easy because of enclosure vibrations, let me know a bit more to improve help...

Have you changed out your guitar cable? Also, if you have a broadcast antenna close to your practice area, that could be your problem. Try moving your amp to another location and see what happens. If it picks up stations at different locations that are miles apart, call Marshall...the amp is defective.

Hi J Wade. I'm Dave P. I'm not a guitar amp expert or technician but I've been using amps and effects for 35 years and there are a couple things I can suggest.

That kind of periodic noise/switch noise can be a symptom of having the polarity of the amp reversed. If your amp has a 3-position OFF/ground switch, try reversing the ground. If it doesn't, take the plug and turn it around. Just don't get near a microphone unless you're sure your amp is grounded the same as the P.A. It could fry your lips off.

Dirty switches to that too. You said the noise is in time with the delay's tap time which is set by a foot switch. If tapping that switch the first time generates a pop, the delay may have catch it and is repeating it. Turn off the amp, remove the delay foot switch and turn it back on. Still noisy? If not, give the foot switch a good cleaning.

When you turn the EFFECTS knob up, is it scratchy? Might need the potentiometer cleaned. What happens when you specifically turn the DELAY level down all the way while using the other effects? Noise still there?

That's all I've got. Hopefully, it was helpful. Don't wrack your brain over this too much. There could very well be an internal problem with your amp that will require a trip to the shop. You don't want to open it up yourself. Rock on but be safe.

Dave P.

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.

may be one of the electrolytic capacitors in the power supply has become leaky...this is a common problem among amplifiers...so you let it cool down..then after a period of time the capacitor heats up and then causes the hum...the power supply caps filter out the 60 hertz ac line noise...which is probably the frequency of the sound it is making...this is a good indication of these caps going bad....another thing you can check is to see if the amp is properly grounded(eg: the ground pin on the plug is present) and that you dont have an open cord or input

All amplifiers make a little bit of noise (hiss) but it is normally slight and drowned out by playing. However, assuming that this is not normal system hiss, here are a few simple steps to try and locate the source of the problem by process of elimination.

1. SAFETY FIRST - a common cause of a humming or buzzing sound can be a lack of earth (grounding) on the mains supply. With a 240volt AC supply this hum will be at 50hz (in the UK) - frequency may vary in other countries but should be similar. Check the earth first because of risk of electric shock. Until you are satisfied that this is not the cause of the problem DO NOT touch any metal parts of the amp. Remove the mains lead and try a different one. Try plugging the amp into a different mains outlet socket (preferably one on a completely different circuit).
2. Turn off other electrical equipment in the vicinity that may be causing interference. Move the amp a bit, try rotating it by 90 degrees to change relationship to things like mains electric cables in the floor.
3. If you are using the line-out socket to give a feed to a mixer, slave amp or p.a. system unplug this. Sometimes double earthing (through the mains lead of your amp AND the mains lead of the MIXER / PA) will cause an 'earth loop' due to a different resistance at each end. Putting a DI box with an 'earth lift' in between may eliminate this problem. Alternatively there are little gadgets you can buy to do this (I found one intended for car audio systems on Amazon that works very well)
4. Unplug any instrument leads - to eliminate possibilities of interference affecting cables, effects pedals or guitar pick-ups. Also unplug the foot-switch.
5. If that stops it plug a lead in without a guitar on the other end - does the noise return? If yes change the lead. If no plug the guitar in.
6. Try moving the guitar in relation to the amp (turn it around 90 or 180 degrees) - this will be pick-up to amp power supply interference.
7. Does the sound get better or worse if you touch metal parts of the guitar with your hand? This may be a screening issue within the lead or the guitar itself.
8. Try turning all the individual channel tone and gain controls to zero, turn off any effects on the amp panel. If that eliminates it only turn up the controls on channels that you are actually using.

I would try hitting the side of the amp before turning it on. There may be a loose piece of solder or other conductive particle stuck somewhere. Bang the cabinet rather hard with your fist. If that doesn't help it might be a loose solder connection at a resistor or capacitor but a tech should check that out.

There are some basic things you can try before you suspect the amp. Does your guitar cord work in another amp? Is your guitar sending sound through your guitar cord? Without any thing plugged into your amp can you hear a slight hiss when you turn your controls up on your amp? Here is a link to some things you can do to troubleshoot the problem:http://www.geofex.com/ampdbug/ampdebug.htm Even though the info is for tube amps a lot of it also applies to solid state (transistor) amps like yours.If it turns out to be the amp and you don't feel comfortable working on it and have no one that you know personally to do it you are best served by taking it to a certified Marshall repairman who will have the tools, parts and schematics to help you.

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