[Amps] SB220 step start blows fuses

Zev Darack zevdarack at gmail.com
Mon Jun 26 10:02:59 EDT 2017


The filter capacitor assembly can slide out during reassembly and short to
the chasis which would cause the stepstart to blow.....just something to
check in your troubleshooting.

Zev N2WKS

On Mon, Jun 26, 2017 at 8:28 AM, Catherine James <catherine.james at att.net>
wrote:

> Any time the fan doesn't start immediately after power-up, shut down your
> SB-220 **immediately**.  You may have a short, and if the breakers/fuses
> don't blow, you will smoke the power supply very quickly.
>
> 73,
> Cathy
> N5WVR
>
> --------------------------------------------
> On Mon, 6/26/17, Warren Volz <warren at warrenvolz.com> wrote:
>
>  Subject: [Amps] SB220 step start blows fuses
>  To: amps at contesting.com
>  Date: Monday, June 26, 2017, 1:54 AM
>
>  All,
>
>  I’ve been restoring a SB220 and
>  finally got to the testing stage this weekend. When I turned
>  it on, the HV went up to ~1kV and then started to drop.
>  Successive cycles of the power switch did nothing. Oddly,
>  the meter lights and fan never started running. I looked at
>  the bottom of the amp tonight and the 3A fuses I added to
>  the W7RY step start board blew. What areas should I look at
>  now to determine what is going wrong? I have both tubes in,
>  and I believe I previously checked them for filament shorts.
>  I’m worried the HV supply has an issue.
>
>  Any advice would be very much
>  appreciated!
>
>  Thanks!
>
>  -Warren
>  KD5YPH
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