Broken Marshall MG

[cokekolev]

Hi, I got an old MG15CD second hand. I used to have one until a few years ago, but then I switched to tube amps. But I kinda missed it as I loved the crunch it had, but found the stock speaker too thin. So I modded the new one with a speaker output. It worked great for an hour or so. Then I played again through the stock speaker with the clean channel on 5 and when I hit a chord harder, it started crackling. After a while it just got real quiet and the fdd switch doesn't work anymore. What could be the problem? And is it worth repairing?

 

[BowerR64]

Clean the iput jacks, get some deox-it from radio shack you will use it alot as a musician for alot of things. Spray the jacks and push a cable in and out a few times.

If you can open it up also spray the control pots. I like to tip em upside down and they spray into the pots and let the spray run down into the opening in the pot case.

None of my older MGs ever had any of the pots fail, the newer ones with the splatter graphics have but the older MG series 3 with the FDD buttons had issues with the headphone jack.

When you plug in headphones it kills power to the speaker so your not playing loud at night with your headphones on. This jack can get dirty and the output starts to cut in and out.

It still could be another issue like maybe you plugged the + of the output to your modified jack to ground? or some issue there?

 

[cokekolev]

I already tried the things you suggested. The contact cleaner did the trick, but it only lasted for about 5 minutes. I cleaned every pot, switch and jack. I'm taking it to my guitar tech tomorrow, he fixes amps too.

 

[ampmadscientist]

Hi, I got an old MG15CD second hand. I used to have one until a few years ago, but then I switched to tube amps. But I kinda missed it as I loved the crunch it had, but found the stock speaker too thin. So I modded the new one with a speaker output. It worked great for an hour or so. Then I played again through the stock speaker with the clean channel on 5 and when I hit a chord harder, it started crackling. After a while it just got real quiet and the fdd switch doesn't work anymore. What could be the problem? And is it worth repairing?

Is the new speaker jack connected to the chassis ground?
Or did you use a plastic insulated jack?

Did you try the amp into another speaker? (the speaker could be blown)

Headphone Jack:
The switch contacts can fail inside the jack. This causes the speaker to shut off.

 

[cokekolev]

Is the new speaker jack connected to the chassis ground?
Or did you use a plastic insulated jack?

Did you try the amp into another speaker? (the speaker could be blown)

Headphone Jack:
The switch contacts can fail inside the jack. This causes the speaker to shut off.

I used a plastic neutrik switched jack. I drilled a hole on the particle board back panel for it. The problem persists with the stock speaker, an external cab and the headphone out.

 

[Ghostman]

If the problem comes about after a few minutes, then it's definitely a heat issue.

 

[cokekolev]

If the problem comes about after a few minutes, then it's definitely a heat issue.

No, now it's there all the time.

 

[ampmadscientist]

No, now it's there all the time.

You might consider re-soldering jacks and controls.
Could be a cracked / broken solder connection.