Srsly?

[Smokebreak]

A stranger emailed me and ended up giving me a busted JCM800 DSL 100. He said no one in town could fix it. He said the first tech he took it to said it had a "fuse blowing problem". No kidding. Anyways, he didn't even ask me to fix it. He said he was going to throw it away and asked if I wanted it.
So of course I took it.
I haven't had a chance to open it up much less look at a schematic.
What would you do with it? I'm very unfamiliar with these amps. Gut/rainyday project funtime, or fix and sell?

[Phil_S]

If fuse blowing means the PT is toast, then you have to decide if you want to muck with it. That problem is easy enough to figure out. You'll get better opinions if you can make even a tentative diagnosis. I think you've got a rainy day project -- a fixer upper.

Couldn't fix it is BS. Even I could fix it and I haven't seen it. I guess no one wanted to bother with a proper diagnosis. Maybe the owner wasn't willing to pay for the bench time?

[Littlewyan]

Which is it? A JCM800 or DSL100? If its a DSL100 then I think the power transformer secondaries are all connectors so you could just completely disconnect them, hook up a lightbulb current limiter, turn it on and see if that bulb shines bright. If it does then PT is toast, if not then there could be hope.

Edit: I'm guessing you mean JCM2000 DSL100. If you can fix it then it might be worth a bit.

[darryl_h]

There were a number of problems with early Marshall DSL/TSL amplifiers which are documented here: http://www.lynx.bc.ca/~jc/TSL122.html

[Buschman]

Seems I worked on one for a neighbor with a bias issue. Scary stuff and work on copiers for a living! Fix it up a bit and trade it off to Guitar Center!

[Leo_Gnardo]

JCM2000 have a well known problem with bias drift due to board material that becomes conductive with heat and time. The most troublesome spot is betwen pins 5 & 4 of output tube sockets. Some good folks in Germany posted their solution, link follows. I've fixed at least half a dozen of 'em. Or you can throw down $300+ and replace the board entirely.

http://www.hullerum.de/Marshall/TSL122repair.html

[Smokebreak]

Wow what a nightmare, and I'm glad I asked! Sorry guys , I indeed did mean JCM2000. Thanks for the links.

[Leo_Gnardo]

I indeed did mean JCM2000.

Thought so! Fix n sell, drum up some holiday cash so you can be a generous Santa. When they're working right, the 2000's sound pretty darn good.

[Littlewyan]

Repair it like Leo and others have said. You can buy replacement boards for £99 over here but I imagine they'll be exactly the same and have exactly the same issue down the line.

[guitarmike2107]

Only takes 10 minutes to get it out the box and look for burning marks etc then another 10 to check the PT.

I had one that needed a power socket replaced due to arcing, easy fix really

[Leo_Gnardo]

Presumably Marshall got a handle on the problem and JCM2000 from 2006 on don't have this bias drift problem. 1998-2005, they're all candidates for Hullerum-style board drilling & resistor replacement. If you decide to go the Hullerum route, I find it neater and safer to remove output tube sockets, drill or Dremel-carve hole thru the board at pins 5, then reassemble. With the sockets in place, whatever Dremel bit you use, it crashes into the metal pin, possibly breaking the bit or chunks of metal from the pin and sending them flying maybe into your face, who needs that. Safety glasses on please anyway. Removing & replacing sockets takes longer no question, but safer & neater in the end.