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Post by phil0333 on Mar 8, 2018 17:20:56 GMT -7
Hey, I've got a 2003 2X10 combo. Amazing amp for sure. Recently, It's started having issues at really low volume (like bedroom volume). If I hit the strings pretty hard, the amp distorts and sputters badly. At higher volumes it doesn't do it, maybe rarely. Any reason there would be issues mainly at really low volume? Just replaced power tubes today with brand new ones, no change. Preamp tubes have been swapped around with others I know are good. the socket on v1 is a little "loose" feeling, but I can move that tube around with the amp on and it doesn't make any noise. I'm wondering if it's the volume pot or a cap on the volume pot maybe? I've poked around with a chopstick and don't see any bad solder joints, etc. I'll try to add a video tonight. thanks! Phil I did send an email to repairs and they suggested ruling out tubes. I did that but wanted to ask here before I email them back. Maybe somebody knows a quick fix
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Post by wubberdubber on Mar 8, 2018 18:05:43 GMT -7
Almost sounds like something's "loose"...a solder joint...a socket...a potentiometer...some things can loosen up over time. I'd start by taking off the knobs, make sure all the pots are snug, check the switches and jacks, etc.
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Post by Chilly Gibbons (Todd T.) on Mar 9, 2018 13:04:22 GMT -7
And tighten the screws on the tube sockets, trannies, jacks, etc. Tighten everything!
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Mar 9, 2018 13:24:53 GMT -7
Exercise the volume pot?
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Post by zpilot on Mar 9, 2018 17:22:42 GMT -7
^^^^ Yes, it sounds like a volume pot problem. Cycle it several times. It might take 30 to 40. It's not uncommon when an amp (any amp) gets a few years on it. If that doesn't do it it might need cleaning with Deoxit, or even replacing.
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bradm
Junior Member
Posts: 74
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Post by bradm on Mar 9, 2018 21:17:44 GMT -7
Question - did the front (or control section) of the amp ever take a bump that you know of? I've seen with issue with a pro's JCM900 (he has a pair he gigs with..150 shows+ a year). Anyways, because he bought padded cases (at my insistence) I now see less of this...but, I'd see one or the other on my bench. Pots would either sheer or deform.
How they can deform is this...a brief, but moderate tap on the front and the pot's posts get a push. This can force the post to slam in and start deforming the back of the pot and, at times, push the back casing so that it's back cover's attachment prongs loosen. After a bit of abuse, the casing loosens enough that now the wiper and disk in the pot have trouble keeping contact midway. If this is happening, you can reform the tabs...just take a flat blade screwdriver and press them back in.
If this is the case, you usually see it happen more significantly at 11-1 range on the pot...and diminish when either near off or fully on. Turn it volume control down to 2 or so and note if the condition improves...then nearly all the way up with no input, but controls maxed and listen for random noise issues. If it's more prominent in the center of a control's range, it's likely that pot.
That said, at this age it could be oxidation anywhere...speaker jacks, input jacks...can't exclude caps, etc.
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Post by Maddog on Mar 10, 2018 5:03:24 GMT -7
Deoxit: pots, jacks, switches, SOCKETS, every contact point the amp has.....
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Post by phil0333 on Mar 10, 2018 22:45:18 GMT -7
took it apart and cleaned/tightened everything I could. Today I had no problems, so hopefully it's solved.
thanks guys. We'll see if it comes back
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