| Right (reverb/trem) channel problem on K 150 [message #14563] |
Mon, 18 October 2010 18:58  |
tommyd
Messages: 1
Registered: October 2010
Location: Chicago
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Junior Member |
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Hi,
I'm new to the site and based in Chicago. My newly acquired 1970s K150 only runs on one (left) channel-both left inputs work, but neither of the right channel inputs work. I have cleaned the contacts, double-checked the solder work, resoldered a few loose items, etc. Does anyone have the schematic? Is there anywhere to get these fixed that doesn't cost a fortune?
Any common parts failures and parts sources?
Thanks!
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| Re: Right (reverb/trem) channel problem on K 150 [message #14565 is a reply to message #14563] |
Tue, 19 October 2010 07:52  |
stevem
Messages: 4746
Registered: June 2004
Location: NY
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Senior Member |
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Hello and welcome to our obsession.
Since you stated that only your left channel works I will assume you have a combo model K150 and your effects channel is working, but the normal channel is not.
Eitheir way its the same deal in regards to the problem though, you have more than likly a dead transistor.
In fact right now as I type this My K150 combo(K150-8 model) has the effect channel that has crapped out on me two weeks ago, so your not alone!
I do have schematics should you need them but most times its the first transistor gain stage that that the signal hits after the input jack(s) that gets blown out in any Kustom amp. In these amps they started using a new type/number transistor in some stages so a common NPN type ( 2N3904) replacement will not do, but I do recall that the first gain stage is just a 2n3904 type.
You can try a simple signal test out like so.
Take a real small full metal screw driver, and with the knob side of the board facing you touch each leg of each transistor with that channels volume up some and the reverb up some also.
Start off on the left side of the board and work back to the right side where the input jacks wire in.
when you touch a gain stage that is working you will hear a pop/noise from the speaker, and this pop will get louder as you move left to right thru working gain stages,
Where the popping sound stops will most likly be your dead stage and transistor.
Some stages just do the tremolo and such and may not make a pop, so when you do find a dead section continue to the right to confirm that the next true gain stage is working or dead.
Let us know what you find out, and be truly carefull as to not short across the transistor leads with the screw driver and be carefull on the 120 volt AC ( switches, fuse and such) side of the amp, the boards only run on 12 VDC and pose no shock hazard
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