Please help!!!

[madialex]

I have a Crate V5112 tube amp, I know I know, I shoulda bought a real amp, that aside.
Today I was playing it as always and the power went out, got my meter and the power fuse was blown, got another fuse, amp powered up, started playing it, after about the 3rd note the fuse blew again. The only thing I have noticed is in the last few weeks it has been noisier than usual as far as 60 cycle hum, I turned off my computer monitor and it seemed fine, hardly any noise at all. This all started today after I swapped out the neck PU in my tele, It had a short in the PU so i fixed it, installed it and didnt realise I caught it under the small e string, plugged it in and very loud humming, the fuse blew then. Fixed the PU again, installed it carefully this time, Played it about 3 seconds and the fuse blew again.

Question: The fuse I replaced the old one with is a fast blow 2amp 250vlt buss fuse. It has the single strand of thin filament, the original had a coiled type filament, same value, 2amp 250vlt. Is the fuse I have now not going to work because it is a fast blow?

Thanks for any help, I am not a wiz at electronics so all help is very much appreciated. Thanks.

[Amp Kat]

It could be as simple as that but fuses blow for a reason and most likely is a bad power tube. Even new tubes can be bad out of box so if it's a 100 watter pull two and see if you can get a combination to work. There could be other things causing the fuse to blow and it is possible that a slow blow may work.

[madialex]

Thanks Amp Cat, it is the 50 watt version, it only has 4 tubes and I am by no means an electronics guy, I know just enough to shock the crap out of myself

BTW- do you think by the PU being shorted to ground making the loud humming could have caused it, it was very loud humming and thats when it blew

[Amp Kat]

Hum is caused by bad tubes,mismatched tubes,bias failure or bad filter caps or a lost ground so I'm thinking definitely tubes or something in the power section for sure.

[madialex]

Thanks again....
I have 2 el34 power tubes, when I pull 1 tube and run it with the other out, it does not blow the fuse and visa sersa, so I guess the tubes are good. So something is putting an extreme load on the circuit other than the tubes. Looks like I will be off to my amp tech tomorrow. It figures, i'm broke as all get out, I guess it will have to sit there till I get the cash. I think I am going to trade it on one of those Roland cube amps, I have heard good things about those. I dont play out anymore and use the amp basically for testing guitars and pickups, though I love a tube tone, maybe a pro Jr??? Any suggestions on a small tube amp that is not an arm and leg to buy would be appreciated as well.... Thanks again Amp Kat

[madialex]

FWIW, I have the amp apart where I can see the tubes and such, I put both tubes back in, turned it on and just sat and waited. This time, it started to crackle like before but it didn't blow the fuse, but 1 of the tubes had what looked like lightning run up through it, from the bottom to the top and then back down, I turned it off during this but it did not blow the fuse, probably would have had I left it on a second longer. This is very weird to me.

Does this tell you any more about what may be going on?
I am trying to arm myself with enough info to not get totally screwed by the amp tech, not saying he would screw me over but I still like being informed a little before having any work done plus it makes the tech think I may have a clue about what he is doing and charging me for.. Thanks.......

[Enzo]

If the original fuse was a slow blow type - the little spring shaped inner element - and you install a fast blow fuse, yes it will blow often as not. Use the proper type fuse.

If it still blows slow blow fuses, then a new set of power tubes is likely what it needs.

[madialex]

I think I narrowed it down to 1 of the power tubes. I put them in again 1 at a time and just listened to the amp without playing. 1 tube was quiet and never crackled or anything. The other in by itself again and the crackling sound started up about 3 seconds after turning the standby off. I also noticed the middle part inside the gray thing in the center did not glow blue like the other one that didn't make any noise. I also think I remember the top glowing but not the bottom on the said bad tube. Maybe not.