[vcf-midatlantic] Any trick to discharging ADM-3A

Ian Primus ian.primus.ccmp at gmail.com
Fri Feb 9 17:34:48 EST 2018

I just loosen the screw holding the yoke clamped in place so it can be
rotated. Then, turn the monitor on, and rotate the yoke with my hand
until the raster is level. Shut it off, then use your screwdriver to
tighten the yoke in place. Tighten the screw down until the picture
tube implodes, then back it off a quarter turn.  :)   But, seriously,
don't crank it down super tight, just enough to hold it snug.

When rotating the yoke, don't touch the terminals where the windings
are connected. Those will give you a very painful shock. Avoid
touching the windings themselves if possible - just grab it by the
plastic part.

Technically, you can loosen/tighten the yoke clamp with the power on,
but there is no reason to, always a chance to drop the screwdriver
into it. Similarly, the windings are insulated with enamel - you can
touch them, but I avoid it because there is no reason to touch them
and any crack or damage in the insulation will certainly be noticed.

You don't need to discharge the tube unless you plan to disconnect or
otherwise touch that second anode connection. The bell of the tube is
grounded, and the yoke itself is insulated wire on a piece of plastic.
The neck of the tube is just clear glass and has no electrical


On Fri, Feb 9, 2018 at 5:22 PM, E.M.F. via vcf-midatlantic
<vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> Adm-3a follow up question:  The raster on mine is rotated slightly. I had to center it by rotating the ring magnets. I did this powered on with insulated tools (chopsticks). I was planning on discharging the tube before I loosened the yoke and rotated it. Any thoughts or tips on rotating the yoke?
> Eric

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