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Post by billyguitar on Apr 30, 2006 15:29:22 GMT -7
I bought a Carmen Ghia a while back from Tele62 (Curt). I thought it sounded good but I kept getting a screeching noise on some notes. I thought it was the V1 tube socket having a loose pin. Today I finally decided to look the amp over. I took the chassis out to drain the caps and have a look around. Saw a weird thing. The cap and the big resistor that make up the conjunctive filter were disconnected. Not on purpose by anyone but the legs had come unsoldered from each other. It appeared the legs were just held side by side and soldered together. Solder isn't glue and those legs should have been twisted together and then soldered. So I did that. Then I shot some cleaner in the V1 socket and worked the tube in and out a few times and then did it again. I tested it and I heard the screech once, a little bit, so I think I've fixed it. So after listening to the amp with and without the conjunctive filter I must say it should stay in the circuit. The amp is definitely smoother and more refined with it. Dr Z made a good call on that. Without it I'm reminded more of a Fender tweed amp. Not that that's a bad thing but I like a smoother amp. It also seemed to tame some of the overbrightness I had been hearing. It also has more clean headroom but after 12:00 it roars beautifully. So if you have a feeling that your Ghia might be too bright and distorts too much too soon, check out the conjunctive filter. If you don't know how to drain the caps don't work on anything inside yourself! This amp doesn't have a lot of caps to shock you dead but it might! And remember, that's with the amp unplugged from the A/C!
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Post by pickupcentral on May 1, 2006 19:44:10 GMT -7
Same thing happened to me. I was getting a horrible static noise when playing a chord. The two components of the conjunctive filter were de-soldered. I removed them. I will probably replace it one day, but I am digging it as is. I don't know about "tweedy", but it is nice and thick, even with single coils.
It does change the character of the amp, though.
-Phil
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Post by billyguitar on May 3, 2006 11:48:07 GMT -7
When I first got mine I thought it was nice but wasn't quite sure what the hub-bub was all about. Now that I've fixed the conjunctive filter I'm liking this amp more every time I plug in. Thanks DR Z!
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Post by Curt on May 4, 2006 7:01:09 GMT -7
Hey Billy, I just saw this post......Did it look like it may have been knocked loose in shipment ?
I did not notice anything "loose" looking...?
Is there anything I need to do here ?
Curt
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Post by billyguitar on May 4, 2006 8:44:58 GMT -7
No worries, mate! Except for getting the chassis in and out it was a 60 second fix. Most of that time was getting the soldering iron hot. Might have come loose in shipping but the old solder was really grey looking so it looked like it was loose a long time but you never know.
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Post by Curt on May 4, 2006 9:01:37 GMT -7
I never really studied it as I swapped it rather quickly prior to boxing her up. Makes me wonder if it was loose the whole time I had it ?!?!?
damn thing rocked !!
Well I'm glad you could take care of it easily, I do A/C work and know to ground capacitors to unload them, is it the same with amps? I've never repaired them but have a growing interest.
Curt
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Post by billyguitar on May 4, 2006 10:28:08 GMT -7
I have the procedure in a Gerald Weber book so I always refer to it when I drain the caps. It's easy enough, you just clip a lead on a ground and then on a certain pin of a preamp tube for a minute or so, and then repeat that by clipping on a pin of one of the output tubes for a minute or so. I don't remember the exact pin numbers that's why I'm not being mre specific. I've also seen guys just take a screwdriver and short the filter caps to grounds. I think they like to see the sparks! All of this with the amp unplugged and the amp on play. I'm still always careful, even after I drain everything. That's all there is to it.
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Post by Curt on May 4, 2006 11:52:10 GMT -7
Same as what I'm used too, thanks.
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Post by pickupcentral on May 5, 2006 6:27:17 GMT -7
I have the procedure in a Gerald Weber book . Do you remember which book? -Phil
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Post by billyguitar on May 5, 2006 8:12:56 GMT -7
I'm not home now but I'll try to remember to look later and give you the info.
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Post by billyguitar on May 5, 2006 16:49:42 GMT -7
The Gerald Weber book is 'A Desktop Reference Of Hip Vintage Guitar Amps'. The chapter is entitled 'How To Make Your Amp Sound Right'. Unplug the amp and then turn the on switch on and the standby switch to play. Page 121 say use a jumper wire connected to the chassis, the other end connected to pin 1 (first pin clockwise from the gap) of any preamp 12AX7 or 12whatever. Wait about a minute for the caps to drain. then to finish draining the caps take the jumper off of the preamp tube and hook it on pin 3 of a big bottle output tube or pin 7 on an EL84. Give it a few seconds and the caps will be drained. If you go away from the amp a while drain the caps again just for insurance that you did it right. I've done this and never been shocked but as you know just because you read something on the internet doesn't mean it's true!
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