Amps
[Top] [All Lists]

[Amps] SB220 step start blows fuses

To: <amps@contesting.com>
Subject: [Amps] SB220 step start blows fuses
From: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 11 Jul 2017 07:39:39 -0700
List-post: <mailto:amps@contesting.com>
Date: Thu, 6 Jul 2017 00:07:50 -0600
From: Warren Volz <warren@warrenvolz.com>
To: amps <amps@contesting.com>
Subject: Re: [Amps] SB220 step start blows fuses

Thank you for the flood of good suggestions. I'm getting closer.

Without tubes and with the HV transformer unplugged, the fan and meter lights 
work. In addition, the step-start fuses don?t blow!

That leads me to suspect the tubes + HV supply. I checked the windings on the 
HV transformer to look for shorts:

BLK-YEL = .7 Ohm
BLK-BLKYEL = .6 Ohm
BLKYEL-YEL = 0 Ohm
BLKGRN - BLU = .8 Ohm
BLKGRN - BLKRED = .6 Ohm
BLU - BLKRED = 0 Ohm

Do any of those look off?

##  Yes,  I already mentioned this b4 !   You should be seeing 9-10 ohms
across the plate xfmr sec...with  plate xfmr sec NOT connected to the diode 
board. 

##  IF the diodes in the diode board fail, they typ fail shorted.   If you still
have the diode board connected to the plate xfmr secondary,  you will also
see  close to 0 ohms across the plate xfmr sec. 

Jim   VE7RF 
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>