[Amps] KQ2M ACOM 2000A Amp. S/N 990171 "Heater Current Too Low" problem

[Bob Shohet, KQ2M]

Hi,

My ACOM2000a had been working perfectly since Feb 2017 after being repaired for a “Heater Current Too  Low” problem.   At THAT time it turned out to be the cheap plastic connector failure – which overheated and burned/discolored – (I had heard the telltale “Thunk” and smelled a slight burning smell.)   With the amp working perfectly for the previous few days, I turned it off before leaving for Thanksgiving dinner.

The next morning (the day of CQWWCW) I turned it back on and IMMEDIATELY, after ~ 3 seconds - got the dreaded  “ Heater Current Too Low  0.00v ” message.  So the amp doesn’t work.  It’s like they KNOW when it is most advantageous for them to fail.

I tried all the usual strategies – inspecting the HV area and underneath the tubes, reseating the tubes, removing the transformer and checking all the fuses and plastic connectors for damage/failure and then reconnecting them.  I also swapped RCU’s with another working ACOM2000a and swapped outlets, just in case.   I then turned on the amp and FAILURE after the same 3 second “boot-up” period”.  Same error message “ Heater Current Too Low  0.00v ”   UGH!

Something apparently changed in the amp between the time that I shut it off on Thursday evening and when I turned it on again early Friday morning, but I have no idea what happened or what changed.

Does anyone know what the problem could be or what I should look at next?  I would really like to be able to diagnose and fix this myself if possible.

Tnx & 73


Bob  KQ2M