[TenTec] TT 422 Amp Filament Transformer Problem?

[Mike, K9UW]

Joe, I also own an early 422 and just updated it with the "Bias Mod for 
422" from TenTec.  This mod kit includes a replacement for the original 
Filament AC Board and features a circuit that cuts off the bias when the 
rig is in transmit but is in idle.

While installing the mod, I discovered that the wires providing AC to 
the old board (at terminals H and J) were stranded, and that all but one 
of the strands had broken on each wire.  I have no idea whether the 
failure of the strands was a recent event or if they had been broken for 
some time. 

Given the intermittent nature of your problem, perhaps this condition 
exists in your 422 as well? 

73, de Mike, K9UW
Amherst, WI
http://www.k9uw.com



k0bx at arrl.net wrote:
> I got a Older TT-422 Amp a few months ago.  Works fine and in good condition.  Then one day I turned it on and nothing light up, that is, no panel lamps, it looked dead.  As I looked around on the amp, I found that the 2 3-500Z's were on?
>
> Reading the manual, it seems that when the amp is turned on, voltage is applied to the filament transformer.  From there, there are two output taps, one go's to the tubes and the other one go's to the QSK Board to provide voltage for the + 12 VDC Supply.
>
> This is where the problem is.  There was no voltage at the connector to the QSK board.  When I played around with the connector and the two wires coming from the filament transformer.  The amp came to life.  I figured the connector on the wires needed a good cleaning which I did.
>
> All worked for a few weeks.  Then it happened again, no voltage to the +12 supply.  I left the amp on for a few minutes with only the filament voltage to the tubes on.  Suddenly, the amp came on.  I didn't do anything, I had not open the case.
>
> I suspect the filament transformer has an intermitent in the transformer tap that supplies the voltage to the +12 Volts supply.
>
> I wonder if anyone else has had a problem like this??  The TT-422 amp has been around for a longtime and anything that could go wrong has.
>
> Any help or comments.
>
> Joe K0BX
>
>
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