[TenTec] Fw: 9420 P/S Problem....Need Help

[Bob Good]

Second posting.  Anyone with some experience with a 9420 > Herc II setup ? 
I certainly could use some help.  Thanks,  Bob  K4BG

-----Original Message----- 
From: Bob Good
Sent: Monday, April 20, 2015 15:57
To: TenTec at contesting.com
Subject: [TenTec] 9420 P/S Problem....Need Help

Greetings “Tentechnical” Friends........  I have a problem with my old 
“reliable” OmniVI > Hercules II (with 9420) > 238 station.  I have concluded 
the problem is with the 9420.  Omni straight through is fine.  Disconnect 
the 9420 and run the Herc off a battery, works fine.  Here is the symptom: 
While bringing the power up to about 200 watts output into a dummy load with 
a 1.2:1 swr,  a relay starts to chatter in the power supply.  The pilot lamp 
in the Herc (now a led) almost extinguishes with each pulse of the relay. 
Monitoring the Voltage, the Herc Meter indicates it just wiggles at about 14 
volts indicated.  The RF output appears to drop out with each relay pulse 
and the current meter wildly fluctuates.  I have all the manuals by Ten Tec 
and have looked at the diagrams.  I have opened the top of the unit and 
nothing is burned.  Harness plugs appear to be seated.  I am assuming the 
problems lies with the circuitry on the P/S controller board involving 
either K-3 or K-4.  I have not tried to go further by hooking the 9420 back 
up to the Herc after disassembling the P/S unit.  I have not yet checked 
voltages inside.  Of course, it is running on “220” vac.  I am hoping some 
of you perhaps have had the same problem and can help me step through the 
repair.   All my info on QRZ is current.  Thanks for reading and please 
spread the word.  Regards,  Bob K4BG
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