15th May 2012
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#1 | | Gear interested
Joined: May 2012
Posts: 13
Thread Starter | question about a '72 fender champ that doesn't work in some outlets
Hey folks,
So I've owned several Champs of this era over the years and this is a new problem for me. Basically, the amp usually works totally fine. In my house, at least. Even when I take it other places it usually works, but if I take it somewhere where I really need it (like a gig) it seems to get stage fright and when I turn it on nothing happens. I have no idea what makes it not work in some outlets and be totally fine in others. If it's through a surge protector or right into the wall, there doesn't seem to be any correlation. Sometimes it will work on certain outlets and not on others. Any ideas? I don't think it used to do this but I have no idea what might have caused it to start malfunctioning. It's even more frustrating because it works fine most of the time but it might as well be broken since I can't depend on it if I'm using it somewhere else.
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15th May 2012
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#2 | | Gear Guru
Joined: Feb 2004  |
Change the power cable. Use a heavy gauge 3 wire grounded connector and solder/bolt the ground wire to the chassis.
This is assuming that the pilot lamp also does not lite up.
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15th May 2012
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#3 | | Gear interested
Joined: May 2012
Posts: 13
Thread Starter |
Yeah, the light doesn't come on. The power cord has already been changed from the stock cord to a grounded one, though. What's the reason that the cord would like some outlets and not others?
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15th May 2012
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#4 | | Gear Guru
Joined: Feb 2004 |
An ittermittant plug connection. Cut it off and install a heavy Hospital grade power connector on it.
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15th May 2012
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#5 | | Gear interested
Joined: May 2012
Posts: 13
Thread Starter |
So should I just cut off the end and put on a new plug or take the whole thing out?
thanks for the help
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15th May 2012
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#6 | | Lives for gear
Joined: Jan 2008
Posts: 1,953
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I'm with Jim on this. Are you checking the outlet before you plug into it? Bars/clubs are known for having horrible power/wiring going on; Home Depot sells a $5 circuit tester to at least ensure the circuit is wired properly. I'd also check to ensure the outlet works for other gear to rule out bad wiring.
Besides the power cord, with the amp off and cooled down, ensure all the tubes are securely seated, including the rectifier tube.
When was the last time you had the cap can replaced on this amp? If the answer is never, you're probably due...
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15th May 2012
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#7 | | Lives for gear
Joined: Apr 2007 Location: Maryland
Posts: 5,347
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Could it actually be that the slider switch has gone funky? On both of my Champs I have to finesse it into the right spot to turn them on. It's just one of those lovable quirks about Champs, so that whenever a guest wants to power them up, I have to reach over and say "no, there's a trick to it" before they can play.
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15th May 2012
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#8 | | Gear interested
Joined: May 2012
Posts: 13
Thread Starter |
I haven't checked the outlets with a circuit tester, but the times this has happened other amps worked fine in the same plug. I've never had it serviced or dug around in there so I don't know about the caps but it does sound great when it works, which is pretty much always (except when I REALLY need it to, of course). Do you think the cord has a bad ground?
I remember asking a gearhead friend of mine about this a while ago and he mentioned the switch as well, I'm not sure why that would change from outlet to outlet but I suppose I could just be blaming a bad switch on something else.
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15th May 2012
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#9 | | Lives for gear
Joined: Nov 2010
Posts: 2,888
| Quote:
Originally Posted by kafka  Could it actually be that the slider switch has gone funky? |  | |
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16th May 2012
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#10 | | Gear Guru
Joined: Feb 2004 |
If you have a loose power slide switch, REPLACE IT!
If those prongs that hold it together are loose and it pushes in, you can get electrocuted by that.
Death is bad for repeat business...
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16th May 2012
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#11 | | Gear maniac
Joined: Apr 2012
Posts: 268
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Mojo has a nice 3 prong, get a strain relief
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16th May 2012
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#12 | | Lives for gear
Joined: Jan 2008
Posts: 1,953
| Quote:
Originally Posted by Jim Williams If you have a loose power slide switch, REPLACE IT!
If those prongs that hold it together are loose and it pushes in, you can get electrocuted by that.
Death is bad for repeat business... | Certainly worth the <$5 price to replace it... Fairly certain the bright switch on other Fenders is the same as the Champ power switch. Mojo Switches | |
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17th May 2012
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#13 | | Lives for gear
Joined: Apr 2007 Location: Maryland
Posts: 5,347
| Quote:
Originally Posted by Jim Williams If you have a loose power slide switch, REPLACE IT!
If those prongs that hold it together are loose and it pushes in, you can get electrocuted by that.
Death is bad for repeat business... | But I LIKE the little tingle I get whenever I touch my Champ and another piece of gear when it's running. It's like licking a 9v battery. :-0
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14th June 2012
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#14 | | Gear interested
Joined: May 2012
Posts: 13
Thread Starter |
I seem to have fixed the first problem, but while I was fixing it I noticed that after the amp warms up for 10 or so minutes, it starts making a crappy crackling noise when I play, sort of like distortion, but the kind that doesn't sound good. It's silent when not playing. Preamp tube?
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14th June 2012
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#15 | | Lives for gear
Joined: Jun 2010 Location: Del City, Oklahoma
Posts: 1,476
| Quote:
Originally Posted by manraykindofsky I seem to have fixed the first problem, but while I was fixing it I noticed that after the amp warms up for 10 or so minutes, it starts making a crappy crackling noise when I play, sort of like distortion, but the kind that doesn't sound good. It's silent when not playing. Preamp tube? | Could be. Hard to say for sure. Swapping out preamp tubes is easy, and you should always have backups, because like light bulbs, they don't last forever. I'd also check the input jack just to make sure it doesn't have a bad connection and it crackles when you move around with the guitar and pull a bit on the plug. If neither one of those two fixes it, try swapping out the power tube. It can also cause similar problems to the one you described. And since the Champ is class A, you don't have to worry about biasing it.
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14th June 2012
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#16 | | Gear interested
Joined: May 2012
Posts: 13
Thread Starter |
I think the treble pot is just dirty, just adjusting it made it go away (derp)
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