[Elecraft] Elecraft KPA500 sn 1910 dead, update.

[AJ8MH Radio]

Did you get this email?  The parked green and red wires and the 
connected yellow wire should have voltage with only the rocker switch on 
the back engaged.  These are connected to the secondary of T1. If you 
don't have any voltage, I'd suspect the fuse/switch module.

You can unplug the module and check where the wht, yel, ble and blk 
wires connect.  Check with Elecraft and see what pin in 115vac and what 
pin is neutral. The module is a pm0sxdbx0 power entry module, and you 
can look for a spec sheet on the web.  I think Mouser has them in stock 
or you can get one from Elecraft.

There are two additional fused lines that run to transformer T3. This 
transformer supplies voltage for the 12 and 5 volt regulators and the 
interlock switch.

On 1/17/2022 2:57 PM, Sam Sargent via Elecraft wrote:
> Elecraft KPA500 sn 1910 dead.
>
> UPDATE 12/17/21
>
> First. Thanks to everyone who has responded to mypost.  I have read all comments withinterest and have responded to several folks who offered ideas that I havetried.  Thank you for trying to help.
>
> SECOND. Here is a bit of extra info that I havediscovered.  I disassembled the fuse blockand cleaned all contacts and the fuses with the “Deoxit” product.  I configured my “OWON HDS272S”meter/oscilloscope to measure resistance and noted that the leads are about 0.7ohms.  I connected the meter leads to theflat prongs of the 115vac cord that was plugged into the fuse block on theKPA500.  With the rocker switch on thefuse block 3 in the OFF position (o) the meter showed zero (0) ohms.  With switch 3 ON (!) the meter showed 2.8ohms.  Thus, subtracting the resistance inthe meter leads, the resistance through the fuse block changed from 0 ohms to2.1 ohms.  I connected the 115vac cord tothe wall socket and went through the power up procedure.  No joy. I listened for the hum of the transformer, and there was no hum.  I am flummoxed!
>
> CONCLUSION.  Thisleads me to believe that the power cord, fuses, and fuse block are functioning.
>
> I think that my next step is to look into the possibilityof sending the KPA500 to a repair facility. I am open to your ideas.  73 Sam
>
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-- 
Joe Hutchens
AJ8MH - Radio
Marquette, MI