ADM 3a with no horizontal scan

Eric Christopherson echristopherson at
Thu Apr 7 23:34:52 CDT 2016

On Thu, Apr 07, 2016, Seth Morabito wrote:
> Hey folks,
> I've been on a tear trying to resurrect old projects here, and next on
> the list is an ADM 3a.
> This particular 3a has no horizontal scan. None at all. I just get a
> vertical line down the center of the screen. First thing I checked was
> the horizontal deflector on the yoke, which seems secure.
> Before I go diving into the schematics, I figured I'd ask here: Is
> this a common failure mode? Has anyone else experienced no horizontal
> scan on a 3a? Any tips on where to look first?

Is this the same one that was showing all exclamation points on every
other line?

        Eric Christopherson

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