JTech Posted March 6, 2007 Report Share Posted March 6, 2007 Hi people at PG. I recently received a Peavey Bandit 112 scorpion equipped amp from a close friend. This is one the older models like this one. Well I went home, plugged in my guitar and it was working perfectly, after a while the volume just went all the way down. I tried turning it off then on but i was the same. I had to put the volume close to 10 so I could here something. Then all of a sudden the volume came back. I almost crapped my self because I left it on 10 . I opened up the amp to see if any thing was loose, checked the cables, everything seemed fine. Then I noticed that there was transistor with one of the outer legs not soldered to the board. I was going to solder it back but I wanted to check if it's supposed to be like that or what could have happened.Is that the answer to my problem or could it be some other factor. Can someone out here help me out please. Thanks in advance George Quote Link to comment Share on other sites More sharing options...
curtisa Posted March 6, 2007 Report Share Posted March 6, 2007 Did the volume gradually fade out, or suddenly cut off? One channel or both? I used to have one of the old Peavey Express amps that had dodgy effects loops jacks - the contacts on them would occasionally open up and result in a sudden loss of volume. Plugging a lead in and out of the sockets a few times would temporarily fix the problem until the contacts gradually opened up again. Replacing the jacks would permanently fix the problem, cleaning them would also work. If the volume drops again, you can test the effects loop jacks by plugging a lead from the effects send jack to the effects return jack. If the volume comes back up when you plug in to the loop, one or both of the effects loop jacks are probably the problem. This may sound kinda stupid, but if you hit the amp can you make the problem come and go? That would indicate the problem is to do with loose connections, dry solder joints or other poor connections. Without seeing a schematic for the amp I couldn't tell you if that transistor is meant to be soldered like the way you say. Can you post a photo of the offending component and surrounding circuit board? If the amp initially worked for a while before dropping out I would guess that the transistor isn't the problem. Another one to check, if your amp is fitted with it, is the external speaker socket - if it's designed to bypass the internal speaker when a lead is plugged in it can develop the same problem as the effects loop jacks. Beyond that I'd be looking at the circuit board itself and checking for fractured traces or fractured solder joints. I once fixed a Peavey VTM60 head that would drop in volume randomly. The problem was traced back to a resistor with a cracked body - replacing the resistor fixed the problem. Cheers, Curtis. Quote Link to comment Share on other sites More sharing options...
JTech Posted March 6, 2007 Author Report Share Posted March 6, 2007 Well I have tried smacking it, but that didn't help. The volume just goes out instantly Here is a pic of the transistor I'm talking about and its surroundings. Ok I did the thing you told me about plugging in the effect send to the return jack and the volume did come back. Is this the right way? http://img413.imageshack.us/img413/1809/im000858rv1.jpg Now what? I thought that the problem could be the input jacks and not the effects send - return jacks. Not enough time but I'll try to check. Thanks for your help George Quote Link to comment Share on other sites More sharing options...
curtisa Posted March 6, 2007 Report Share Posted March 6, 2007 Well I have tried smacking it, but that didn't help. The volume just goes out instantly Here is a pic of the transistor I'm talking about and its surroundings. Looks like it's in the input stage of the amp, doubt it's the cause of your problem, but I have no idea why only 2 of 3 legs would be connected. Some kind of mod by a previous owner maybe? Bah! Need the schematic Ok I did the thing you told me about plugging in the effect send to the return jack and the volume did come back. Is this the right way? Sounds like you've found the problem, and yep, you've got it connected right. Well, the easy solution is to leave the lead plugged in but it certainly isn't the most elegant solution. Have a closer look at the effects loop jacks when you get a chance. If they're the same type as the input jacks (which I can just see in the bottom-left corner of that photo you posted), they'll have little metal tabs that are shorted across the top of the jack when no lead is plugged in, and that lift up when the lead is inserted - you can try cleaning the point where the two contacts meet with isolpropyl alcohol (will be damn fiddly though). You may also get good results if you use extremely fine wet-and-dry paper, fold it in half, and slide it in and out a few times between each contact. Also check that each pair of tabs actually meet when the jack is removed from the socket. Check the solder joints on the sockets underneath the circuit board - look for any cracked or fractured solder joints and remelt any that might be there. You may need a magnifying glass and strong light to see any really fine cracks. Hope that helps Quote Link to comment Share on other sites More sharing options...
crafty Posted March 6, 2007 Report Share Posted March 6, 2007 (edited) Ah...the joys of working on Peavey amps. At least their customer service is good when you call 'em to order parts. I would have suggested the volume pot may have gone bad as on my similar Audition 110, but it sounds like you probably hit it right with the effects loop jacks. BTW, they use those Re'an jacks that are supposed to be the toughest input jacks around, but I've worn out four of 'em on my 12-year-old amp. Edited March 6, 2007 by crafty Quote Link to comment Share on other sites More sharing options...
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