Marshall G100RCD trouble.

[toff88]

Hey, my marshall g100rcd i recently bought from a friend is giving me a hard time. At first the sound is perfect but after playing a while, the volume drops, but by knocking on it the volume returns to normal. I have checked the grounds but it didn't help. Does anybody have any clues what it could be? //Toff

[52 Bill]

Welcome to the board and Happy New Year as well.

Obviously, something is loose or is not making contact in your amp. That's why when you knock on it the sound comes back.

The first thing to check is if your amp has an FX loop or pre-amp out/ power amp in jacks. If the closed connection on the jacks becomes oxidized and does not make a solid contact, the sound will cut out as you described. Try pluging in a spare guitar cord from the out to the in and see if the problem goes away.

Another thing to check if your amp has one, is the headphone jack. If it becomes dirty it will cut off the speaker connection and kill the output. Try a set of headphones and see if the signal still cuts out.

Beyond these things, then you will need to check for loose or broken parts on the circuit board inside the amp.

[Enzo]

Yeah, plug a spare cord onto the effects send jack and hte other end right back into the effects return jack. If this restores the sound, then the return jack needs service or replacement. If it stil does it, even that way, ball up your fist and whack the top of the amp. if that has an effect, something is loose inside. Oh, turn down the reverb first. Check the solder to that large 10 watt 0.33 ohm power resistor.

[toff88]

by checking the circuit board i found out that some components were loose, when I fixed them it began to work again. but thanks for the replys! Happy new year.

[itchyscratchy]

HEY I'M HAVING THE SAME PROBLEM WITH MY AMP, BUT IT'S THE BOOST CHANNEL. THE GAIN WILL NOT GIVE ME ANY MORE CRUNCH. IT JUST SOUNDS LIKE THE CLEAN CHANNEL. IS THIS A COMMON PROBLEM WITH THIS AMP? (Marshall G100RCD).