| help for semi-smoked K200A [message #2666] |
Sat, 12 April 2003 07:30  |
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Hi, I just bought this Kustom K200A, it arrived and looks great,
serial #20974 -- it does *not* have reverb or tremelo
I assume it is an early one because it says "BY ROSS INC." on the front, but
it is not the "Frankenstein" type
the seller said this about it's current electrical condition: "It over
heated while being played and everything still works but the amp now has
little volume and distorts constantly"
what is most likely to be the problem given this hint?
I am a pro at repairing vintage tube amps, but a real novice on solid state,
does anyone have a source for the original transistors, transformers, or a
schematic? does anyone at least know who built the original transistors and
transformers and what model # they were?
thanks,
wild bill
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| Re: help for semi-smoked K200A [message #2926 is a reply to message #2914] |
Wed, 09 July 2003 10:37  |
stevem
Messages: 4863
Registered: June 2004
Location: NY
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Senior Member |
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Hi bill.It sounds like a problem in the driver section of the amp, if both channels do the same thing. this would be the board mounted on the back wall of the amp. the power suppply regulation for the 8 volts positive and negative to the two preamp boards on the front of the amp come from that board also. their is a red wire and a green wire from the rear board to one preamp board, then it jumps to the other. Check for that 8 volts positive and neg, from each to ground. the biggest problem with these amps is working on the boards, the cabling is to short to get the boards far enough out of the amp to work on them. Quite a few times Ive had to make up moldex plug extention cables to work on them. The blue wire feeds the preamp signal to the rear board, you can inject a test tone into their and see if the driver section/output section is OK.If you remove the preamp board/s to test, you have to maintain the ground conections to the boards.I have schematics.Each board has a PC number on the side facing the wall its mounted to, let me know what you need and mail me a self addressed stamped envelope and and make you copys. Steve magnotti 548 yorkhill rd yorktown N.Y 10598. Getting transistors is not a problem, If fact, new ones get rid of alot of the white noise the amp has. I would also replace the rectifier bridge, new ones are far and away better. A 10 to 15 amp one is plenty.I have 15 tube guitar amps myself, and grew up on fixing tube TVs and amps. The point to point tube stuff is much faster to repair and modifie, and when set up right with good matched, and bias set output tubes and N.O.S preamp tubes sounds like heaven.
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