RSDx Posted March 14, 2009 Posted March 14, 2009 Worked fine last night.....turned it on this morning, the hum sounded diffferent (very quiet...LOL), so I turned it around (back is off since I replaced the tubes a while back) and when I set it down, heard a faint crackle and saw a few sparks by the EL84 socket area (under the tube kind of inside the chassis, visible through the hole for the tube.. No output sound ..... Strange, as nothing is loose in there that I know of, dunno if something shorted ???. Turned it off, cooled down, tried reseating the tubes, power back up and no sound (I can hear slight "sound" when the volume knob is turned, but it's just from the pot - absolutely no guitar sound getting through). Both tubes light up normally, just nothing comes of it. Am guessing I should check the fuses (although something must be wrong for a fuse to blow, yes???). If fuses are OK, what the heck do y'all suppose happened to my VJr ???!!!??? Hope it ain't dead already...... don't finish re-school and start working 'til sometime next month - plenty of time to figure out what I need to get fixed, I guess.... Dang, it's always something, it seems..... ](*,) ](*,)
cGil Posted March 14, 2009 Posted March 14, 2009 Ever seen a light bulb blow? Check the fuses for sure, but it's a tube amp, so definitely try some tube you know are good. If you don't have any spare tubes, get a bunch, because sometimes you'll find 'em DOA fresh out of the box. Gil...
RSDx Posted March 14, 2009 Author Posted March 14, 2009 Ever seen a light bulb blow? Check the fuses for sure' date=' but it's a tube amp, so definitely try some tube you know are good. If you don't have any spare tubes, get a bunch, because sometimes you'll find 'em DOA fresh out of the box. Gil...[/quote'] Hey, GiL ..... Yes, both tubes that are in there have working been fine for a few weeks now. I also have 2 used sets of tubes that worked fine when previously removed.... none of them work in any combination now....amp powers on, all tubes light up/glow orange as usual/normal, but the amp's not humming like it did and no guitar sound output....I hope something important isn't fried......crap !!! And, yeah, have already experienced doa's out of the box before. Had to return 2 faulty 12AX7s to get a working one from the local shop ....
m-theory Posted March 14, 2009 Posted March 14, 2009 The main fuse is 2a, yet the amp doesn't draw even a full amp. You could probably get by with a .5 a fuse as a main. In other words, if something does short out inside, you CAN cause damage that a proper size fuse would prevent. You're probably going to have to pop the chassis out and take a look inside. Sparks in an amp are never a sign of glory.
Dave Posted March 14, 2009 Posted March 14, 2009 I'm just guessing here, but he has glow, which indicates filament voltage present. Doesn't that come from the mains fuse through the power transformer (6.3vac?). The crackle when he set it down while powered up, being centered around the tube socket, makes me suspect a fatigued solder joint to the socket. It's common with hot components and the symptoms support that. I'm not a TV repairman, I'm a Tech Rep for other types of products, but I have fixed two Mitusbishi 52" and 62" TVs lately (one of which was mine) where the Horizontal and Vertical convergence ICs overheated the solder joints and turned the solder on the pads to dust. One of them had no solder left on one pin, just a hole with a pin sticking through it. Heat is our enemy... I'd check the board with a strong magnifier or eye loop and see if there's a cracked or damaged solder joint on the tube sockets. Look closely and you may see the problem. There's high voltage present so UNPLUG THAT SUCKER first!
m-theory Posted March 15, 2009 Posted March 15, 2009 The crackle when he set it down while powered up, being centered around the tube socket, makes me suspect a fatigued solder joint to the socket. I'd say that's a real good guess. This is, of course, THE major fault of PCB-mounted tube sockets.
Recommended Posts
Archived
This topic is now archived and is closed to further replies.