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

[Bob Good]

Thank  you Billy for the info.  I'll try and locate a replacement.  I am 
thinking about shotgun repair to also replace the transistors Q-1 and Q-2 as 
they seem to have to do with relays K-3 and K-4 which seem to be doing the 
chattering.  I will be sure all the pots are adjusted to the correct 
voltages.  Other than accessibility, that does not seem too difficult for 
this old timer.  Regards,  Bob

-----Original Message----- 
From: Billy Cox
Sent: Friday, April 24, 2015 14:48
To: Discussion of Ten-Tec Equipment
Cc: Tentec at contesting.com
Subject: Re: [TenTec] Fw: 9420 P/S Problem....Need Help

Hi Bob,

Find U1, the 7815 regulator and see if you can monitor
the voltages coming out of it?

A friend's 9420 had some odd problems at one time, and
with help of those on here, I was able to track it down
to the U1 7815. Replacing it made everything work OK.

Hope this helps!

73 de Billy, AA4NU

----- Original Message -----
From: "Bob Good" <k4bg at planters.net>
To: "Tentec at contesting.com" <TenTec at contesting.com>
Sent: Friday, April 24, 2015 1:21:24 PM
Subject: [TenTec] Fw:  9420 P/S  Problem....Need Help

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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