Lee Flier Posted August 25, 2001 Share Posted August 25, 2001 Hey all - I've been having something weird happen with my old Fender Vibro Champ that I've been using for small gigs. It seems to sometimes just cut out with no warning and then, after a few minutes, I can get it to come back on. When it stops working the power-on light stays lit and the tubes keep on glowing, but no sound comes out. This first happened when our band played its first gig where I used the Champ. I thought at the time that it was a bad cable, and I suppose it still could be - except that I've been using the same cables at rehearsal and at bigger gigs where I use a different amp, and I never have had the problem then. It's only when I use the Champ. The on-off switch on the Champ is a little flaky, like a lot of them are, and I do plan on getting it fixed or replaced, but like I said I don't think this other problem is the switch because the power light stays lit. Is there anything you guys can think of that might be causing this? It's pretty bizarre! Thanks,Lee Link to comment Share on other sites More sharing options...
Tedster Posted August 25, 2001 Share Posted August 25, 2001 I HATE problems like that...'cause inevitably you take it in to a tech, and he can't find anything wrong with it. But, that's what I'd do...take in to a tech...especially if you've got one who happens to be a friend, who won't mind you sitting there playing through the amp until "it" happens...then you can point your finger at the thing and say "AHA!!!", and he'll hear it and have a better clue. I would say something is loose...could it even be a bad speaker connection? Does it crackle and fitz when it happens, or just go dead? Any hummmm? Does anything happen when you knock the amp (jiggling a bad connection, perhaps producing a couple of broken seconds of normal tone)? "Cisco Kid, was a friend of mine" Link to comment Share on other sites More sharing options...
Lee Flier Posted August 25, 2001 Author Share Posted August 25, 2001 Yeah, I'm going to take it to a tech... problem is, the one I normally use is out of town and I have another gig next Friday. BUT... I was just at my local guitar shop and found a little Ampeg for $250 that will do nicely for the gig. I can get at least that much for the Champ on eBay - once I find out what the freakin' problem is and fix it so I don't saddle some poor buyer with it! Honestly it's not really big enough for even these coffeehouse gigs we've been doing on occasion, so I really needed something else anyhow. When the amp goes dead, it just goes dead - doesn't sputter, doesn't hum, nuthin'. Jiggling the cable or the on/off switch has no effect. It happened twice last night, both times it was later on in the evening when the amp was pretty hot, and within a fairly short time of each other. In both cases, after I shut it off for a couple of minutes it came back on. GRRRR... Of course I was also switching out cables and stuff while all this was going on, so it's hard to really say whether it was the amp or the cable... but at this point I'm inclined to think it's the amp. I will check it out further though. While I was at the guit shop, I did, however, manage to score a new tape for my Echoplex (Dunlop has started making these again! Yay!) and a new foot switch for the tremolo on my blackface Pro Reverb. Yippee! --Lee Link to comment Share on other sites More sharing options...
Scott from MA Posted August 25, 2001 Share Posted August 25, 2001 Sounds like there is a hairline split in the circuitry, and when it heats up it opens. This is actually pretty common, but can be very difficult to find, because when the circuit cools the split closes again. Bring it to someone who can trace it with a oscilliscope. What they will do is, when it heats up and opens, check for signal after each stage of the pre-amp and amp. That will narrow it down to one section. Once they know what stage it's in, they should be able to find the open through voltage drops. Scott (just another cantankerous bastard) Link to comment Share on other sites More sharing options...
strychn1neaol.com Posted August 25, 2001 Share Posted August 25, 2001 Hey,I have had similar problems with amplifiers before. If your greater all of the connections the problem usually goes away, if that is what the problem is. Bad connections are the only problems I have ever had with my gear. Link to comment Share on other sites More sharing options...
Scott from MA Posted August 25, 2001 Share Posted August 25, 2001 Originally posted by strychn1ne@aol.com: If your greater all of the connections the problem usually goes away Say what? http://www.musicplayer.com/ubb/confused.gif Scott (just another cantankerous bastard) Link to comment Share on other sites More sharing options...
fantasticsound Posted August 26, 2001 Share Posted August 26, 2001 Scott beat me to it! Heh, heh.. The reason you don't hear crackle is it works like a gate. The board literally heats up until it separates. there is little chance the connection could be made again without the amp cooling down. As opposed to heavier, loose connections where the suspect part disconnects and reconnects when you shake the amp/connection. Good call, Scott! http://www.musicplayer.com/ubb/smile.gif ------------------Neil Reality: A few moments of lucidity surrounded by insanity. It's easiest to find me on Facebook. Neil Bergman Soundclick fntstcsnd Link to comment Share on other sites More sharing options...
lrbreez Posted August 26, 2001 Share Posted August 26, 2001 I had an amp that did that. I got a floor fan and put it behind the amp to blow on it. Never had anymore trouble with it. Still have the amp though I had to get another fan. I moved up to Vornado fans.Buddy Link to comment Share on other sites More sharing options...
Lee Flier Posted August 26, 2001 Author Share Posted August 26, 2001 Thanks for the tips guys, I'll bet you are right about what the problem is. And Buddy, the fan sounds like a good idea although it looks like I'll probably sell the amp now so I want to just get it fixed. I'll have my regular tech check it out when he gets back into town, now that I'll have this badass little Ampeg Jet reissue for my gig Friday. --Lee Link to comment Share on other sites More sharing options...
DC Posted August 26, 2001 Share Posted August 26, 2001 Have you tried another set of tubes? Nearly all problems with tube amps are tubes. -David http://www.garageband.com/artist/MichaelangelosMuse Link to comment Share on other sites More sharing options...
Chip McDonald Posted August 27, 2001 Share Posted August 27, 2001 Back when I used to use a pair of vintage Marshall amps I solved a lot of head aches by clamping one of those 6" fans you can get at a drug store (I mean, a "CVS", since it looks like they're WalMarting Eckerds and Walgreens) onto the backs of them. ... but that was when I bothered to also haul out a good size rack and a pair of 412 cabinets, among other items. Sigh. ------------------New and Improved Music Soon: http://www.mp3.com/chipmcdonald Guitar Lessons in Augusta Georgia: www.chipmcdonald.com Eccentric blog: https://chipmcdonaldblog.blogspot.com/ / "big ass windbag" - Bruce Swedien Link to comment Share on other sites More sharing options...
lrbreez Posted August 27, 2001 Share Posted August 27, 2001 Ampeg Jet reissues are real nice.Buddy Link to comment Share on other sites More sharing options...
strat0124 Posted August 27, 2001 Share Posted August 27, 2001 Originally posted by DC: Have you tried another set of tubes? Nearly all problems with tube amps are tubes. That hasn't been my experience, however if it works...cool. I'd have to agree with the heat issue, probably the output power circuit, but that's hard to wild ass guess about. I've had a couple amps burn a component that only shows after expansion, gettin hot. I doubt its the transformer cause it wouldn't work again if it smoked. Plus the Champ only has the one power tube, can't remember if it's just two preamp tubes...been awhile. It's a simple circuit, probably be able to see the faulty component visually. Anyhow, get a knowledgeable electronics guru to look.....you'll not even need an oscope to TS this unit. p.s. Have you put an after market speaker in it? It's also a possibility that the connections on an old speaker coil get hot and seperate, then cool off and work again. Wish I had it on my bench I could probably tell you in ten minutes. Schematics for these are everywhere online. This message has been edited by strat0124 on 08-27-2001 at 01:37 PM Down like a dollar comin up against a yen, doin pretty good for the shape I'm in Link to comment Share on other sites More sharing options...
Scott from MA Posted August 27, 2001 Share Posted August 27, 2001 Originally posted by DC: Nearly all problems with tube amps are tubes. Ummmm... that's not even CLOSE to being a true statement! Scott (just another cantankerous bastard) Link to comment Share on other sites More sharing options...
Submersible Posted August 28, 2001 Share Posted August 28, 2001 The reason you don't hear crackle is it works like a gate. The board literally heats up until it separates. there is little chance the connection could be made again without the amp cooling down. Aren't we talking about a point to point wired amp here? Link to comment Share on other sites More sharing options...
Lee Flier Posted August 28, 2001 Author Share Posted August 28, 2001 Originally posted by strat0124: p.s. Have you put an after market speaker in it? It's also a possibility that the connections on an old speaker coil get hot and seperate, then cool off and work again. Wish I had it on my bench I could probably tell you in ten minutes. This is a '66 Vibro Champ and there are a total of 4 tubes in it. The power on light and all the tubes remain on when the amp cuts out, so I'm inclined like you to think that it's somewhere in the amp to speaker connection... no I haven't tried a different speaker, it's got the original speaker in there. I wish I could bring it to you, too! Don't you guys ever play in Atlanta? http://www.musicplayer.com/ubb/smile.gif --Lee Link to comment Share on other sites More sharing options...
KHAN Posted August 28, 2001 Share Posted August 28, 2001 Originally posted by Lee Flier: it looks like I'll probably sell the amp now so I want to just get it fixed. I've got a Dual Showman and a Bandmaster that are always complaining that they want a "little brother". Just wondering whatcha gotta have for it??? Fixed or as is. ------------------ KHAN (Always hopeful, yet discontent) www.floydtribute.hpwebhost.com So Many Drummers. So Little Time... Link to comment Share on other sites More sharing options...
Lee Flier Posted August 28, 2001 Author Share Posted August 28, 2001 Hmmm, Khan, well people on eBay are getting around $310 for them in good condition. And I don't know what it would take to fix it, so I don't know how great I'd feel about offering an "as is" price unless you'd like to make me an offer. Mainly I would just like to make back what I paid for the Jet - $250. Anyway you're welcome to email me an offer if you'd like, and for you, I'll consider it. Other than the problem I have stated, it's a badass little amp, and it is definitely all original 1966. I've had it since the mid 80's and I would feel good if a friend had it and I knew it went to a good home. http://www.musicplayer.com/ubb/smile.gif --Lee Link to comment Share on other sites More sharing options...
thx1136 Posted August 28, 2001 Share Posted August 28, 2001 My Dual Showman did the same thing (or at least it sounds like the same problem) Scott is right. With the Showman apart and on I used a chopstick (non conductive ya know) and was thumping lightly around. When I flexed the board that the wiring runs over and around I recreated the problem. Bad solder joint in one of the resistors on the board. Easy to fix and it's ran solid ever since. Mine was easy to find, yours may or may not be. A good repair guy should be able to find it quick for you if you don't want to do it yourself. Hope this helps. ------------------ Visit BooneRock.net - Play the Rustech Blend'r-great amp, great tone! This message has been edited by thx1136 on 08-27-2001 at 10:47 PM Link to comment Share on other sites More sharing options...
DC Posted August 28, 2001 Share Posted August 28, 2001 Originally posted by DC: Nearly all problems with tube amps are tubes. -------------------------------------------------------------------------------- Ummmm... that's not even CLOSE to being a true statement! Sorry Scott, I should have said, if it's a Boogie then tubes are nearly always the problem. At least that's been true for me and Boogs for the last almost 20 years. Other than them all I've got is a Fender Bassman and a dead Gallien Kruger bass head. Tubes certainly aren't the problem with the Gallien... -David http://www.garageband.com/artist/MichaelangelosMuse Link to comment Share on other sites More sharing options...
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