[Amps] Amp Supply LK-500 metering

[Dave Hachadorian]

Does this amp have a diode between B- and ground?  If so, and 
that diode shorts, the metering gets messed up.


Dave Hachadorian, K6LL
Yuma, AZ


-----Original Message----- 
From: Ham H
Sent: Wednesday, February 14, 2018 5:56 AM
To: amps at contesting.com
Subject: [Amps] Amp Supply LK-500 metering

I am working on an  amp supply lk-500 that has a strange metering 
problem.
The *plate current meter* reads in the reverse direction.  If I 
reverse the
meter leads I see current of only 100 MA and it does not change 
with
drive.  the grid current metering seems OK.

This was an estate find so status before is unknown,

Here is what I have checked:

All wiring is as shown in the manual
Shunt resistors are good
new caps, rect diodes and equal resistors
tried different tubes
check bias circuit and I see 9 V (9 V zener)
checked meter and it is OK
checked all grounds and looked for shorts in metering circuit.

I thought maybe it was a schematic error so checked equiv amps 
and mine is
wired as they are.

What could possibly be wrong as I am stumped and considering 
parting it out.

I can see that rect board has been worked on but unless someone 
miswired
something and the metering is not like every other amp I am lost.

Thanks

Gary K4MT
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps