tulk1 Posted July 22, 2012 Posted July 22, 2012 My 5F4 Super has started blowing fuses and the pilot bulb. The bulb has been out for quite some time. The fuse blew last weekend. I picked up new bulbs and fuses. Last night I put them in, turned the amp "ON" and it blew the bulb. I pulled the fuse and it looked okay. But later when we went to use the amp we got nothing. Inspection showed the fuse was gone. Probably blew with the bulb, but we were in a bad light situ and couldn't see that well. My question: What would be a simple trouble shooting plan? I really can't do the internal electronics, but I can do tubes. Should I start with the rectifier and go from there? Just need a logical flow before I have to take it to a tech.
fxdx99 Posted July 22, 2012 Posted July 22, 2012 Rectfier is first tube I replace with fuse blowing - and was the cause of the last 2 fuse blow incidents I had (on Allen and PRRI). The bulb blowing, too, is different. didn't do that on the 'blackface' style circuits for me, but maybe it's tied in somehow on the tweed? Infinitely more expertise here than me.
kbp810 Posted July 22, 2012 Posted July 22, 2012 It could be a shorted rectifier tube... it's not tied in, though it doesn't take much to blow those bulbs so the surge/draw could momentarily impact the PT and take out the bulb. If you have a spare rectifier tube laying around you could give it a try... if it blows again, I would take it to a tech. ***Edit for an after thought - did it blow instantly on power up, or did it take a few moments?
tulk1 Posted July 22, 2012 Author Posted July 22, 2012 It could be a shorted rectifier tube... it's not tied in, though it doesn't take much to blow those bulbs so the surge/draw could momentarily impact the PT and take out the bulb. If you have a spare rectifier tube laying around you could give it a try... if it blows again, I would take it to a tech. ***Edit for an after thought - did it blow instantly on power up, or did it take a few moments? Immediately ... this time. The bulb had been out for a while (but it's been problematic since I got it; never really gave it much thought.) Then the fuse blew. Also, channel 1 sizzles a bit. I have a 5U4GB here. I'll give it a shot, see what happens. Thx, guys.
Steiner Posted July 23, 2012 Posted July 23, 2012 Don't let the smoke out! You'll Never get it back in.
tulk1 Posted July 23, 2012 Author Posted July 23, 2012 Don't let the smoke out! You'll Never get it back in. I have a machine for that!
jmac Posted July 23, 2012 Posted July 23, 2012 My amp started blowing fuses and i was told it was the power tubes. Might check them out.
tulk1 Posted July 23, 2012 Author Posted July 23, 2012 So, here's what I see as the initial trouble shooting scheme: New fuse Replace the rectifier Power up Blows - check power tubes. Doesn't blow - power down, add bulb, power up. Blows - take to Tech Doesn't blow -good to go for a while. Any chance the pre's might be consipiring here as well?
tulk1 Posted July 24, 2012 Author Posted July 24, 2012 Blows fuses no matter what. So, it's off to the tech on Wednesday. Argh!!!!
DetroitBlues Posted July 24, 2012 Posted July 24, 2012 What a bummer. Hope it's just something simple. I had a Peavy amp that did that. But being a PCB board, there isn't a whole lot that can be done for that type of amp. At least yours is an old fashion handwired amp that can be fixed quickly.
tulk1 Posted July 24, 2012 Author Posted July 24, 2012 Tech said something about a wanky wire or cap or resisto around the B+ thingy, most likely. I said, sure, sounds good to me!
TalismanRich Posted July 24, 2012 Posted July 24, 2012 Tech said something about a wanky wire or cap or resisto around the B+ thingy, most likely. I said, sure, sounds good to me! DId he have to get so technical about it? At least bring it down to our level..... well, its broke! Personally, I think you should look at the electrisicals you're using.
DetroitBlues Posted July 24, 2012 Posted July 24, 2012 Tech said something about a wanky wire or cap or resisto around the B+ thingy, most likely. I said, sure, sounds good to me! Just be weary if he starts mentioning a flux capacitor..
212Mavguy Posted July 25, 2012 Posted July 25, 2012 What a bummer. Hope it's just something simple. I had a Peavy amp that did that. But being a PCB board, there isn't a whole lot that can be done for that type of amp. At least yours is an old fashion handwired amp that can be fixed quickly. PCB amps are repairable, it's just more of a PITA. Ain't buying no more...EVER. Selling all of mine...Seriously, and they all run great!
DetroitBlues Posted July 25, 2012 Posted July 25, 2012 PCB amps are repairable, it's just more of a PITA. Ain't buying no more...EVER. Selling all of mine...Seriously, and they all run great! I didn't say they weren't, just harder and trouble some. Some are easier than others. KBP modded and fixed by Blues Jr, but my Peavey Valveking was too difficult because they use micro components... That's why I'm choosing to play amps that have been handwired or easy to repair.
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