On May 28, 2006, at 11:20 PM, Jeff Strailey wrote:
> When the amp is powered plate voltage as measured by the internal
> meter is about 1500 volts instead of the 3100-3300 vdc one would
> expect. I've attempted no troubleshooting whatsoever as of yet but
> wonder what could be going on? One or more electrolytics or diodes
> bad in the power supply? Obviously I will need to examine the
> power supply but am just wondering if anyone has seen something
> like this before in this or a similiar product?
I bought an AL-80A last year from an estate and had a similar problem
- HV read about 2200 volts instead of nearly 3000.
The advice I received was that the HV power supply is pretty dead-
simple, and it either produced the rated voltage, or failed
catastrophically.
My problem turned out to be a 1.5 M ohm resistor in the metering
chain that had changed to over 2.2 M ohms. I replaced it with two 750
K ohm 1% resistors in series.
So, the first thing to check is that the instrumentation of the amp
is correct. Be EXTREMELY careful, as lethal voltages exist in the
amp. Good luck.
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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