Re: Monitor problem

[Giorgio Morocutti <giorgio.morocutti@alice.it>]

On Thu, 31 Jan 2008 17:32:59 -0800, "Michael J. Mahon"
<mjmahon@aol.com> wrote:

>Michael J. Mahon wrote:

>Looking at the schematic, I'd suspect C206, a 220uF, 90v
>electrolytic that filters the supply controlling the
>cathode voltage.
>
>It looks like this value was chosen high enough to keep the
>cathode biased above the grid for long enough to prevent
>the un-scanned spot from appearing.
>
>There are other possibilities, but that's what I'd try first.
>
>The simplest thing to do is to substitute another known-good
>capacitor of at least 200uF and at least 90v rating.  If that
>cures the problem, then replace the capacitor.  (Bridging the
>old cap with the new one might work, too, but there's a chance
>that it's electrically leaky, which would interfere with bridging.)

Thanks Michael!

work in progress ...

Giorgio


Giorgio Morocutti
giorgio.morocutti@alice.it
Apple II & Apple III forever !