| Re: K100-2 Hiss but no other output [message #21118 is a reply to message #21116] |
Mon, 11 August 2014 11:22   |
daveobergoenner@gmail.com
Messages: 104
Registered: January 2007
Location: Missouri
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Senior Member |
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Jerry:
Good that you have a scope, it will come in very handy.
The schematic for the K100-2 at this site is pretty clear...better than most.
Try putting your scope probe on the base of Q124, while you have some input to the amp. The base should be the middle lead of the three. See if you have audio getting to that point at least. If not, the problem is earlier in the circuit. If you do have level there, something has gone wrong in the power amp section.
Since you hear the hiss, it's more likely the problem is earlier...but you never know. Someone may have popped the first stage transistor in the preamp, which can be a bit sensitive and fragile.
Kustom used a fair amount of tantalum caps in these amps. They were very high quality caps, but they have the habit of shorting when they go bad, which frequently shunts DC voltages to ground. They are usually orange in color. After 40+ years, they are very good candidates for replacement. I usually replace those in any older piece of equipment...even before I power things up.
Dave O.
Dave 0 Wall-O-Bass
Webpage - <a href="http://webpages.charter.net/daveobieone/" target="_blank">http://webpages.charter.net/daveobieone/</a >
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