[TenTec] 9420 power supply

[Ken Brown]

Hi Tom,

     Another guy has been working on a 9420 lately, and had problems 
with it turning on at all. I believe he discovered at failed IC in the 
control board. Perhaps if the two of you corresponded directly you could 
help each other.

Here is his email address:

aa4nu at ix.netcom.com

    Have you tried powering the Omni VI with a separate power supply? 
There are two ways that the 9420 can get turned on, one is by the 
transceiver and one is directly from the Hercules. I have an Omni VI and 
Hercules with 9420 power supply, and have never powered the Omni VI from 
the 9420, always use a 962 to power the Omni. I wonder if the glitch 
that is giving you trouble might happen only from the Omni VI initiating 
turn on of the 9420. If you have another power supply for the Omni it 
might be a fairly easy thing to try.

Ken N6KB

Tom Macon wrote:
> I have a Hercules II amp with the 9420 power supply that's having problems.  
> 1. When the amp is switched on, the Overload light comes on immediately.
> 2. When trying to run the tranceiver (Omni VI) from the 9420, there is a loud relay buzz from the 9420 followed by something tripping out.  This happens regardless of whether the amp is plugged into the 9420.
>
> The first problem appears to be voltage spike from the 9420 that trips the overvoltage circuit in the amp.  I've been able to capture a 20v spike at turn-on but can't determine which of the four supplies is causing it.
>
> The second problem occurs with either the Omni or a resistive load plugged into the transceiver connector.  Evidently something trips because when the buzzing stops (after a couple of seconds), the output voltage is about 0.62v.
>
> It's very difficult to troubleshoot the 9420 because of limited access to it's internals and it can't be run in a partially disassembled state because many of the cables are too short.  I'm hoping someone is familiar with the beast will have suggestions to help me zero in on the problem(s) - they will be greatly appreciated!
>
> Tom Macon, K9BTQ
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