Thanks Bob, but the power transformer is shot.
It spontaneously died for no apprent reason. Tubes are not shorted, and the
rectoifoers amd
cap are intact.
One of the two primary windings has shorted out completely. The other is OK.
Anyone have a hypersil transformer they would like to sell?
Brian, AF4K
On 30 Jan 2014 at 17:21, Bob McGraw - K4TAX wrote:
> When the power switch is ON there is the HV also applied. Thus I
> wouldn't
> expect shorted tubes or any HV component. Likely the bias diode
> shorted
> thus when switched to Operate the tubes fully conduct and take out
> the fuse.
> Watch for Plate current to peg.
>
> With amp ON and the Operate switch in Standby, you should be able to
> see the
> HV on the meter. The Operate switch basically changes the control
> mode,
> thus the internal T/R switching is activated.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "Bry Carling" <bcarling@cfl.rr.com>
> To: <tentec@contesting.com>
> Sent: Thursday, January 30, 2014 2:30 PM
> Subject: [TenTec] 422 Centurion blowing fuses...
>
>
> >I have a Tentec 422 Centurion that is blowing the main 20 Amp
> fuses...
> >
> > Looking for insights to this amp failure. It started
> spontaneously.
> > I can turn on the main power OK and the filaments light up on
> the
> > 3-500Zs. The 12 volt power supply is OK because the pilot lights
> come on.
> > However when I flip the standby - operate switch to the Operate
> positionm
> > the fuse or fuses will blow. I replaced them with good 250V 20A
> cuses.
> >
> > I checked the plate transformer windings and everything seems
> normal for
> > all three windings. Nothing is shorted. The safety ground for the
> > cover-open condition is not
> > across the HV plate supply. I checked that nothing else is
> shorting out
> > the plate supply
> > either.
> >
> > Does anyone have any idea what might be going on here?
> >
> > Many thanks - Brian Carling, AF4K
> >
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|