On Sat, 24 Mar 2007 15:45:11 +0000, bob.martin wrote:
My kenwood TL922 has developed a strange fault. When I switch it on (via an
Ameritron Soft Start module) I get a negative reading on the Ig meter
of -50mA and a positive reading of around +100mA on the Ip meter with no key
down.

Keying the amp has no effect and the relay does not energise. I have
checked the ALC and relay connectors and the coaxial cables

Taking a quick look at the schematic I'd guess the control-voltage power
supply, also used in the bias circuits, isn't working.

It would be interesting to measure the voltage across the keying jack.
("RL CONT" on the schematic) My guess is it will be very low or zero.
I'm not entirely sure what it *should* be but my guess would be on the
order of 100 volts DC. (so be careful, it may be enough to give you a
shock!)

If this voltage *is* very low or zero, I would be suspicious of D1 or C3.
(or the transformer T2, but I hope not as the transformer will be
difficult & probably expensive to replace...)

I *doubt* it has anything to do with the Soft Start module.