Hi, My M1 head died while working hard in classA.
Now it's back going but crackling like mad in clean channel - this just gets amplified in lead channel (with no input).
Clean volume and tone stack have no effect on crackling. Clean master can vary the crackling volume. So I suspect fault around V1 and V2 area.
Hardly suprising because I have a nice 282v to anodes, and 0v to pin1 of V1 and V2. Pin 3 on V1/V2 is also low(like 0.1v) and pin 8 is a nice 1.7/1.4v for V1/V4.
V3 voltages all good, as are V4.
Good supply from 12v bridge.
The 100k resistors are 99k out of circuit.. the 10nf caps measure 9.9nf each..
Have resoldered all joints around each tube/socket..
No arcing visible, sockets look clean, no shorts under board and tubes replaced.
ANY ideas??
This is driving me insane...
I reckon either I'm missing something super simple or ... I'm missing something super simple..
(I've got suspicions about the opto's and the relay too....)
Here's the schematic:
http://www.schematicheaven.com/newamps/kittyhawk_m1.pdf
Regards, Dave
Now it's back going but crackling like mad in clean channel - this just gets amplified in lead channel (with no input).
Clean volume and tone stack have no effect on crackling. Clean master can vary the crackling volume. So I suspect fault around V1 and V2 area.
Hardly suprising because I have a nice 282v to anodes, and 0v to pin1 of V1 and V2. Pin 3 on V1/V2 is also low(like 0.1v) and pin 8 is a nice 1.7/1.4v for V1/V4.
V3 voltages all good, as are V4.
Good supply from 12v bridge.
The 100k resistors are 99k out of circuit.. the 10nf caps measure 9.9nf each..
Have resoldered all joints around each tube/socket..
No arcing visible, sockets look clean, no shorts under board and tubes replaced.
ANY ideas??
This is driving me insane...
I reckon either I'm missing something super simple or ... I'm missing something super simple..
(I've got suspicions about the opto's and the relay too....)
Here's the schematic:
http://www.schematicheaven.com/newamps/kittyhawk_m1.pdf
Regards, Dave
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