Marshall JCM 600 Amp..blown up?

[JeffB]

I have one of these Marshalls. It's a 60 watt 1x12 combo. Made around 1994/95. Not long after getting it back then, the darn thing crapped out. I heard some sizzling type sounds, then the tone got very muted like it lost all it's high end. Then nothing. No sound.

I never did get it fixed, as I had other amps, and I use it now to run my 1987 head through (speaker is fine). I tried new tubes and a fuse at the time and that didn't help either.

A few days ago, I powered it up again (first time in prolly 8 years) and actually got some volume, but again it was "muted" sounding..no highs..then I heard the sizzle/crackling sounds, and then ...nothing.

Any general ideas what kind of problem it might have, and any general ideas on amp repair costs these days? If it doesn't cost me an arm & a leg, I may just have this amp fixed up and pick up a used 1x12 or 2x12 cabinet and run it through my power-brake instead of grabbing a new amp for practice (it has a master volume & gain controls)

Also anyone else have one of these amps? Looks like they didn't make them very long. Were they unreliable?

 

[jeremy]

Re: Marshall JCM 600 Amp..blown up?

a friend of mine has the 30w version and its cool, and ive played on some 60w, decent amps.
its probably a bad cap or resister. amp repairs can be expensive but it depends on the guy doing it. its a pretty cool amp, id get it fixed if it was mine

 

[JeffB]

Re: Marshall JCM 600 Amp..blown up?

a friend of mine has the 30w version and its cool, and ive played on some 60w, decent amps.
its probably a bad cap or resister. amp repairs can be expensive but it depends on the guy doing it. its a pretty cool amp, id get it fixed if it was mine

Thanks for the info Jeremy. when you say "expensive" do you mean something like $150-$200 or do you mean "You could buy another similar amp for the $ you'll have to spend"?

The local store around here I absolutely wouldn't trust to do anything. One of those stores where they don't even acknowledge you..you have to beg to play/see gear.

There is a Daddy's Junky Music about 30 minutes from me, but I don't know if they do good work or not. Sam Ash is about an hour away...again no clue as to quality of work.

 

[JumpMarine]

Re: Marshall JCM 600 Amp..blown up?

I second Jeremy's advice, it's a great amp. I'm not keen on the stock celestions but with the right speaker set up it screams.

 

[Gearjoneser]

Re: Marshall JCM 600 Amp..blown up?

I've been told by amp techs that the 600's suffer from a poor design layout.
Because the tubes are mounted on circuit boards right next to heat sensitive components, it weakens them to the point of breakdown. What you heard was probably a component or it's solder connection coming to an end. It's best if that's all it is. Hopefully it's not the transformer, but it probably isn't. Probably diodes or a capacitor, or something. Get it fixed, then pass it along to someone else.

 

[JeffB]

Re: Marshall JCM 600 Amp..blown up?

Thank you all for the feedback.

I got home tonight and realized I had said JCM, and not JTM...it's a JTM-60. When I looked at the Marhsall site real quick in the archives today at work, I saw the 600 and said.."thats it"... Don't know if that makes much diff or not. :duh:

Hmmm..just looked on the Marshall site again, and there is no JTM 60 listed, yet the JCM600 series looks exactly the same.

Anyone have the scoop? Did they make a name change or something mid-year?

 

[JumpMarine]

Re: Marshall JCM 600 Amp..blown up?

Someone correct me if I'm wrong, but I think that the JCM 600 was the direct offshoot of the JTM 60 and it added a vent system on the top of the cab to help the overheating prone JTM 60. I think that they are basically the same amp.

 

[Stringer]

Re: Marshall JCM 600 Amp..blown up?

Someone correct me if I'm wrong, but I think that the JCM 600 was the direct offshoot of the JTM 60 and it added a vent system on the top of the cab to help the overheating prone JTM 60. I think that they are basically the same amp.

That's exactly what I understand.

 

[Gearjoneser]

Re: Marshall JCM 600 Amp..blown up?

I knew which one you were talking about. The brown one from 95, right?

Not bad as bedroom amps, but when turned up for loud rehearsals, they have an inherent overheating problem. Out of two guys I know that have had one, they've both had repairs over the life of them. Fix it, and sell it.

 

[JeffB]

Re: Marshall JCM 600 Amp..blown up?

Thank you all again. I'm amazed at the amount of knowledge here on the duncan forums (as well as the friendly atmosphere). So much that I haven't even bothered looking for any other guitar forums since my return to the fold I did manage to find squirreled away on the Marshall site the manual for it.

I'm not sure if I should even bother fixing the dang thing now, and honestly wouldn't feel good about selling someone an amp I know has issues like that..fixed for the time being or not.

Perhaps a place like Daddy's Junky Music would give me a few bucks for it? (then they could fix and sell it, or use it for parts?)

 

[Jeff Seal]

Re: Marshall JCM 600 Amp..blown up?

JeffB, ....hate to be the bearer of bad news, but the amp you are referring to has many known issues....(I have three of them in my shop now for repair...)
Two of them need new Power Tranny's...one is blown, the other is arcing between the heater and the HV internally. The rectifier for the preamp tube stages either will become inoperative or partially fail on a reasonably regular basis unless it's upgraded. The solder connections in these are pretty bad. (As with most of the newer Marshall's except the HW series)
Probably a simple fix, but these are prone to fail....... :blackeye:

I wish I had better news for you.....sorry

Jeff Seal

 

[JumpMarine]

Re: Marshall JCM 600 Amp..blown up?

JeffB, ....hate to be the bearer of bad news, but the amp you are referring to has many known issues....(I have three of them in my shop now for repair...)
Two of them need new Power Tranny's...one is blown, the other is arcing between the heater and the HV internally. The rectifier for the preamp tube stages either will become inoperative or partially fail on a reasonably regular basis unless it's upgraded. The solder connections in these are pretty bad. (As with most of the newer Marshall's except the HW series)
Probably a simple fix, but these are prone to fail....... :blackeye:

I wish I had better news for you.....sorry

Jeff Seal

Jeff, I have a '97 601 what is the chance of this happening to mine? As of yet I haven't had any problems. Am I better off swapping this out while it's still working?

 

[Jeff Seal]

Re: Marshall JCM 600 Amp..blown up?

Jeff, I have a '97 601 what is the chance of this happening to mine? As of yet I haven't had any problems. Am I better off swapping this out while it's still working?

When they work, they work good......but I would honestly say it's just a matter of time before some issue with it comes up.......

...all I can say is I would never gig with one......Fwiw.....
I absolutley love Marshall's and gig with them all the time (800 series), but as with most things, things are becoming more "mass produced" with quite a few sacrifices in the quality department.......sign of the times!

Jeff Seal