JoVega22

Hello, I am a studio guitarist working out of New York.. It is a god send I just found this fourm. When I plug my JCM 2000 in I get no sound. Why is this? I checked all of the wires in back and my cab is f. Thanks For any help. I want to get into fixing and modding amps so this is a good way to start I guess. I have a really important jam session sunday!!

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JoVega22

anyone... help out a nubie?

Fixr1984

Does the power switch even light up?
Did you check the fuses?

Bassmec

First we need to find out if the pre amp works just plug the FX send into another amp.
If that works you are then looking at the power amp and so I am thinking
that you should check the HT fuse if blown remove the output tubes fit a new fuse and if you have four tubes IE. 100 watt amp you can use the two middle tube sockets to test two tubes at a time. Thus with a few combinations and a couple of fuses finding and replacing the tube that failed as its the one that will still take the HT fuse out.
Then re-bias the amp with all good tubes and play loud.
The Switch on the front panel without the red light in it is standby this is the switch that sends the killer voltage to the tubes via the HT fuse.
The switch with the Red light supplies the heaters for the tubes. Does the light come on and are the heaters working in the tubes, are any of the output tubes milky inside and lost the silvering that would indicate a tube that had cracked letting in air.
I could tell you my secret Marshall Service MZ number but then I would have to kill you!.

JoVega22

yea... how do I do that?

JoVega22

the red light turns on... so what now?

rockinr0ll

I think what could be wrong is a wiring got disconnected from the input. You will have to open it up and check it out.

Bassmec

So that means the mains fuse is intact. Test the ht fuse does it look blown?. If it isn't do you have a faint blue plasma glow in the center of the output tubes and a red/orange glow in the top of all the tubes.
Does the pre amp work?. If it don't you could plug the guitar in the fx return socket, thus bypassing the pre amp, you should get a lowish level clean output
if the power amp works.

Bassmec

Possibly with a single minded application to providing accurate and complete information to those trying to assist you.
But this might help:
MIT OpenCourseWare | Electrical Engineering and Computer Science | 6.002 Circuits and Electronics, Spring 2007 | Home

JoVega22

IDK what it look likes if the fuse is broken... and the amp did not work when I plugged it in the FX. So can it be the fuse because the tubes heat up. Here are some pics!

Bassmec

The output tubes have no ht blue plasma in them therefore if you ever manage to track down the ht fuse on the back panel, its the fuse carrier more towards the center of the back panel, you could change it. if it blows again you are looking for replacement tubes and a rebias.
There are a further four fuses inside on the power amp board, do you own a meter with resistance in ohms if so a good fuse will read 0 ohms, a bad one infinity ohms.
Try to replace the HT fuse I think its 1 amp slo blow.

JoVega22

where can I get one?

ayy itss daveee

Don't mean to barge in on the thread...but I have a quick question...

Lately I've been thinking my TSL602 has been sounding pretty muddy... I'm wondering whether its tubes or not.... The above post says the output tubes have no blue plasma in them...My tubes looks just like the ones pictured above (maybe a tad brighter), just a dim orange glow...Is this a problem?

Excuse my "noobness" as my TSL is my first tube amp. Thanks

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Bassmec

Radio Shack still exist?. Any electrical retail outlet, parts connexion
music shops somewhere like that.

Bassmec

No you may not be able to see it, you will only see it if you have EL 34's
I don't know what your amp is fitted with but if you have EL 34's start the
amp from cold leave about 30 seconds and the flick standby off while looking in the output tubes you will see it if the power amp works at all.
How is your amp for bias settings, is it set up properly.

ayy itss daveee

It has Groove Tubes EL34R's I can see from the back... I don't know about the bias settings as I bought the amp used from a guy off Craigslist. I bought it about a month ago. And like I said it's my first tube amp so I'm kinda in the dark...

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MartyStrat54

Now I know why solid state guitar amps are being made and sold. Some times it just makes more sense to try one of them on for size.They're easier to operate and maintain then a tube amp. Of course, I'm smart enough to own a tube amp. I know where to buy a fuse and I'm not a studio musician.


Not meant to be mean, but if you want to ride the bike, you'll need to know how to air up the tires.

Marty