marshall jcm2000 tsl100

[absent_qualia]

i got this amp and played the hell out of it with this shitty crate 4x12 cabinet that was only rated at 80w. Well eventually the HT fuse blew and I figured the tubes were bad. I went to lowes and got some new fuses and tried one with one of the tubes out and it blew again. There are a matched pair of Groove tubes and a matched pair of SED tubes. I took out both of the Groove tubes and it didn't blow, however, smoke slowly starting coming out from around on the preamp tubes, and I could smell electrical burning. The SED tubes were glowing bright blue, so I immediatly turned off the amp. The amp was producing a signal to the cabinet though it was extremely faint. I figured out that the fuse I was using was a 2a and not a 1a. Then I popped in a 1a and with the Groove tubes still out I powered it on. It made sound but still very very faint. I don't know if I should try to get all new tubes for the amp or not. I looked down into the socket that had smoke coming out of it and I didn't see any evidence of it being burnt. The amp still powers on and makes sound even though its extremely quiet, and thats just with two of the 4 power tubes. I don't know if thats normal. I would assume that if I took out 2 of the power tubes that the amp would just play at half the volume. But it is extremely quiet. I need help diagnosing this problem before I pump any money into it blindly, hoping that it will fix the problem. If anyone knows anything about this situation please help me. I got a gig on oct. 28 and I need this amp!

[absent_qualia]

I read another topic about a tsl122 and Enzo i believe said that he dealt with an amp that had a shorted out 16 ohm output jack. ive noticed on mine that you cant even get a speaker cable end to go all the way into the jack. I looked into the jack with a flashlight and it was blocked by a warped piece of plastic. Otherwise, from what I've read on here it sounds like I'm going to have to buy a new output transformer. Should I get new tubes first and see if that fixes the problem?

[tim]

I doubt your OTP is bad....but, that being said...if you have no experience working on these tube amps, I would tread lightly...there are LETHAL VOLTAGES THAT CAN KILL YOU EXTREMELY DEAD! You need to find out what caused the blown fuse and the smoke before you go any further, otherwise you are wasting your money....
If you can't get a speaker plug all the way in to one of your jacks then you probably have a tip from a plug stuck in there...that will cause problems as the jacks switch in and out different impedances, depending on where and how many plugs are jammed into the speaker out jacks....if one is being held open by a miscreant tip, then that could be why the output is low, but I'll bet it has more to do with the smoke you saw...

[absent_qualia]

Thanks Tim for your reply.
I put all new tubes in the amp. I made this decision based on the fact that when i took out the groove tubes it didn't keep blowing fuses. Like I said though I accidently put the wrong type of fuse in the amp. This happened because I had a bag of fuses that all looked the same but some were 2a and some were 1a. The 2a fuse didn't blow but the tubes were glowing extremely bright, I could smell an electrical fire, and saw smoke.
With the new tubes I'm getting the same results so I know that I broke something else, too.

[Lectrkbluz]

You can run an amp with only 2 tubes, but you have to change the output impedance. Usually, you remove one tube from each side of the power section and run the amp with only one speaker. It is a class A/B push pull amp and it needs a tube on each side of the phase inverter tube. The impedance is changed when you remove the two tubes so the speaker load has to change. If you have smoke and burning smell, you should have a technician take a look at the amp. You can kill yourself poking around in there if you do not know much about electronics. The power supply caps retain in excess of 400 volts even when the amp is not plugged in.