guitarfreak21078

Ok I plugged some effects unit into the effects loop of my jcm 2000 head and after about 30 seconds of playing the amp went silent.

I found that the ht fuse had been blown so I replaced it. Now there is sound but it's very quiet. As far as I can tell all the tubes are lit up and considering I replaced them in January I can't imagine they'd be out again but this is my first tube amp and I know nothing about how they should work.

What is wrong wit the amp and what should I do???

MartyStrat54

Patch cable good? The right kind (not a power cable)?

Effects jacks clean and tight?

Never assume your tubes are good because they aren't that old. That is why I rarely use current production tubes...they have high failure rates. I suggest that you get a good preamp tube and swap tubes and see if it makes any difference.

I'm assuming that the power tubes are running okay.

Leave feedback and let me know if you got anywhere.

Marty

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MARTY

2009 Gibson Explorer-Hell Raising Machine
1989 Fender Strat Plus USA
2008 Fender Tele USA
2004 Schecter Elite w/DiMarzio's

TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers.
TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends."
DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker.

Tubes: Let's just say they are NOS that kick ass.

American Viking

first question i always ask is do you know for sure that your impedance is matched and do you understand ohms? mismatched impedance will cause that fuse to blow.

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-I'd rather be a good liver than have one...

guitarfreak21078

I think I have the impedance matched

Is there a way to tell which tube is blown?

rockinr0ll

Check out how they are lit up. If one is blue or not glowing that could be a indication that it is having an issue.

MartyStrat54

It is sometimes hard to tell if the heater in a preamp tube is working. Some are designed so you don't see much of anything. Look for a faint to bright orange glow. The power tubes will be easy to tell if they are working. They have large heaters and you will see them lit up. In a dark room, you should be able to see a little bit of a purplish blue glow when the amp is turned on.

Check what American Viking said. Do you have a 16 ohm load going to the 16 ohm amp output? If your cab is 8 ohm, it should be hooked up to the 8 ohm output. Mismatching the load will heat the output tranny and it will get hot and blow a fuse.

Marty

__________________
MARTY

2009 Gibson Explorer-Hell Raising Machine
1989 Fender Strat Plus USA
2008 Fender Tele USA
2004 Schecter Elite w/DiMarzio's

TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers.
TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends."
DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker.

Tubes: Let's just say they are NOS that kick ass.

guitarfreak21078

I've double checked and I'm running a cable from the 8 ohm output on my amp to the mono 8 ohm input on my 2x12 cab.

All my power tubes are definitely glowing bright so if there is a problem it's in my preamp tubes.

Anyways, I'm still trying to figure out how I blew a fuse. Like I said I plugged a new effects processor in the effects loop right before the amp went out. Could I have screwed anything up then? Does the loop level need to be on a certain setting?

I really appreciate all your help