jcm 2000 dsl help please

[nosignal]

okay, so my ongoing struggle to keep my jcm2000 working has taken another turn. About three weeks ago it just stopped producing sound, so i took it to my semi-local guitar shop and they charged me 115 bucks for what they said was a cracked solder joint that led to one of the tubes blowing up, then about two weeks ago the amp just crapped out again, i took the back plate off and found that one of the power tubes had blow once again, along with both the fuses blowing out as well, so i just bought another duo of power tubes on the internet and replaced the fuses, it seemed to be working fine but today my amp blew out the 2amp fuse. does anyone have any idea what could be wrong with it? Im going to take it back to the guitar shop tomorrow but i just want to see if anyone has any ideas. thanks!

 

[StevenS]

My Shiva was blowing tubes and fuses once. I took it to my tech who couldn't find anything wrong with it except that I had put new tubes in without biasing. He said that was the likely culprit. I have to believe him because it's worked perfectly ever since.

The nice thing about JCM2000's is that they are easy to bias. All you need is multimeter.

Here's the info. http://www.marshallampforum.com/forum/viewtopic.php?t=17

One thing, if you aren't comfortable poking around in these things just take it to a tech.
I'm no expert and have never been zapped but you can get a very bad jolt from an amp if you touch the wrong thing.

Good luck

 

[nosignal]

I put two new tubes in that were the exact same as the ones that were in it when the tech replaced them, then i rebiased it to the same point it was at when i got it back from the tech.

 

[JerryP]

What are you running for speakers? Load box? What kind of volume are you playing at? Does the fuse only blow at high volumes? Any fuzz boxes out front?
Jerry

 

[155]

yeah check the trim pot solder joints and the tube socket joints, is it the same tube blowing?

 

[nosignal]

i use my 1960a cabinet set at 4 ohms and i have a booster, and octave pedal out front, and i run my amp on the clean channel with the crunch button engaged at around halfway or maybe a little more. Yesterday i had band practice at the same volume as today but the fuse didnt blow yesterday.

 

[JerryP]

When using the 4/8 ohm speakers jacks on the DSL/TSL amps the ground side of the jack runs thru the 16 ohm jack. The switch contacts of the 16 ohm jack can become oxidized or dirty and have a poor connection which works out to the same result as playing the amp with no speaker connected. I've seen many failed output transformers and melted 16 ohm jacks on these amps. I've seen lots of high voltage damage on these amps too because of this.
New tubes can fail all by themselves too.
Jerry

 

[myles111]

okay, so my ongoing struggle to keep my jcm2000 working has taken another turn. About three weeks ago it just stopped producing sound, so i took it to my semi-local guitar shop and they charged me 115 bucks for what they said was a cracked solder joint that led to one of the tubes blowing up, then about two weeks ago the amp just crapped out again, i took the back plate off and found that one of the power tubes had blow once again, along with both the fuses blowing out as well, so i just bought another duo of power tubes on the internet and replaced the fuses, it seemed to be working fine but today my amp blew out the 2amp fuse. does anyone have any idea what could be wrong with it? Im going to take it back to the guitar shop tomorrow but i just want to see if anyone has any ideas. thanks!

There are a number of issues with these amps. One of them is a small disc cap in the power supply area that fails easily and causes other problems after that failure.

Somewhere in here there is a post asking about amp techs in Los Angeles and my reply in that thread has the name of a fellow that can give you or your tech more insight into the issue.

As a side note, the JCM2000 series of amps are some of the most difficult amps to keep running on the road in hard tour work where a lot of transport of the amp is involved. If your gigs are local and the amp moved in a car that is not too bumpy of a ride you may get lucky. If the amp moves in a tour bus or equipment truck you may have issues every 300-500 miles

 

[nosignal]

thats really odd that they are so unstable amps. I've had mine for about 5 years or or more, and have only recently had problems with it, the only problems i had with it before was that the power tubes died because they were too old.
And i did have a problem with it about 6 months ago where the 16ohm jack did something and the person i took the amp to then just put a big jumper wire across the jack and told me not to use the 16 ohm jack.

 

[myles111]

thats really odd that they are so unstable amps. I've had mine for about 5 years or or more, and have only recently had problems with it, the only problems i had with it before was that the power tubes died because they were too old.
And i did have a problem with it about 6 months ago where the 16ohm jack did something and the person i took the amp to then just put a big jumper wire across the jack and told me not to use the 16 ohm jack.

Does your amp get a lot of "road time" ?

 

[mobis8]

This is so weird reading this thread... I used to have a JCM2K (used it for about 5 years) that just all the sudden stopped making noise, and started to electrocute me if I touched the output jacks...

Luckily it was being stored in my basement, and someone broke in and stole it. I wish I could have been there when they tried to turn it on for the first time and it shocked the crap out of them haha...

But this is the first time I have read that a lot of people have a hard time keeping them running... That is refreshing knowing I got out of that amp...

 

[Jerry]

Get it fixed and sell it. Run away......

 

[nosignal]

my amp does get some road time, but not nearly as much as it used to, whenever my band plays shows its always in the back of the suv with maybe a backpack on top of it
I'd love to get another amp but I like the way my 2000 sounds and i dont have any money to get another amp.

 

[myles111]

my amp does get some road time, but not nearly as much as it used to, whenever my band plays shows its always in the back of the suv with maybe a backpack on top of it
I'd love to get another amp but I like the way my 2000 sounds and i dont have any money to get another amp.

Talk to Mike Franceschini and have him tell you about the weak cap in the output section that is the source of many problems and how to fix that issue. It is a big reliability fix.

 

[JerryP]

What weak cap in the output section? I've yet to see that one.
Jerry

 

[myles111]

What weak cap in the output section? I've yet to see that one.
Jerry

It is a small disc cap ... call Mike Franceschini for details.

 

[JerryP]

That cap isn't causing the problem.Those caps fail due to high voltage caused by the problems I described. That cap just kills some of the highs. When they fail they go open. The failed cap is the result, not the cause.
Jerry

 

[myles111]

That cap isn't causing the problem.Those caps fail due to high voltage caused by the problems I described. That cap just kills some of the highs. When they fail they go open. The failed cap is the result, not the cause.
Jerry

If that small disc cap fails and shorts other problems follow.

But ... rather than debate this and take the thread off into the ozone I will just say that in my own personal experience supporting these amps on the road there are other amps I feel would be up to the rigors of road work.

 

[JerryP]

If you support them on the road then you know they open when they fail and it's caused by high voltage damage. Even if it did short it wouldn't blow a fuse or make the amp quit.
Jerry