Martin
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Post by Martin on Mar 11, 2016 16:19:25 GMT
Just while I'm all enthused and excited about my imminent foray with a soldering iron while installing some new pickups, I thought about an old amp I've got. It's a 1980s Peavey Backstage 110 transistor amp made in USA, which I've had for around 25 years and which has had a dodgy input for around 24 years  It has a high gain and a low gain input, and for years I simply used the low gain input. Some years ago that also went crackly, and I put the amp away. Digging it back out now, I thought, 'why not use my soon-to-be-newly acquired soldering skills to fix it?' So, I watched a few Youtube vids (as you do) and now know everything about amp repair  I'm actually quite happy about opening it up, taking the head out and disconnecting the PCB (being careful about the capacitors). What's annoying me is that during the amp's period of neglect, a fair amount of corrosion has built up on the back of the speaker and on the reverb box-thing. Will it be okay to give this a rub with some white vinegar once everything is dismantled, or is a new speaker needed? The amp, while decent, isn't worth very much at all, so if it's beyond help, I'll just experiment on it  |
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andrewjw
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Post by andrewjw on Mar 11, 2016 16:48:30 GMT
Sounds like loads of fun in store Martin...
Crackly jack inputs can often be cured by spraying some switch cleaner on a spare jack plug and putting it in and out of the input several times...John Godsland at Orchid Electronics demonstrated this to me on an old Peavey amp I owned a few years ago.....
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Martin
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Post by Martin on Apr 17, 2016 19:27:00 GMT
Well, I finally got around to taking the amp apart and having a go at repairing it. I removed the PCB/control panel from the cabinet and had a look.  Interesting looking CD in the background...    Speaker looks done, but works fine.    It's in bits!  Those knobs need to come off     I looked carefully at the first (hi-gain) input. Inside, it was moving independently of the PCB, so it was obvious that the solder joint was broken, which was causing the input to fail. I tried dripping solder down the small gap, but had no success. I got fed up and left if for a while. In the meantime, I removed all the control knobs and hex nuts to allow me to disconnect the panel from the PCB, but the way it's made stopped me disconnecting the board, so I couldn't get at the underside of the board to solder the input properly. The pots were all sealed, so I did my best to spray some contact cleaner in the front and back of the pots to remove the crackliness (is that the word?) I then had another look at the circuit board, and turing it upside down, I managed to get the tip of my soldering iron between the board and the bottom of the panel and dripped a blob of solder onto the the board while holding the input tight to the board. It seems to have worked! The input no longer moves at least! I put all the nuts and knobs (ok, go on) back in place, reassembled the amp and tested it. Success! The inputs both work. At first the hi-gain input was a bit ropey - it worked and then cut out if I touched the cable, but after a few seconds, it worked consistently, regardless of cable movement. Furthermore, the low-gain input now works without the crackle, thanks to the contact cleaner. The same with the pots. After an initial settling in period of crackliness, all unwanted sounds now seem to have been banished. The amp is now back to good working order, and it feels good to have sorted it. Now it can go on Gumtree for £30  Well worth the effort  |
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Riverman
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Post by Riverman on Apr 17, 2016 19:40:36 GMT
First photo was great, I thought. The rest, less so. |
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Martin
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Post by Martin on Apr 17, 2016 19:49:32 GMT
I don't know how that first photo made it past the forum censors, really. Sorry everyone  |
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Riverman
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Post by Riverman on Apr 17, 2016 20:00:22 GMT
As head honcho around here, Martin, doesn't that mean you now have to chastise yourself?  Perhaps any resulting photos should be password protected...  |
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Martin
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Post by Martin on Apr 17, 2016 20:11:16 GMT
Consider me thoroughly chastised, Richard. I am, in fact, currently tied to a chair in front of a portable TV and subjecting myself to repeats of Last of the Summer Wine  Future photos of a similar nature will, of course, have the offending parts blanked out  |
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Well worth the effort 
Jo whoever he is.
