[HECnet] VT420 with a "worn out" display

[Brian Schenkenberger, VAXman-]

Ian McLaughlin <ian at platinum.net> writes:


On Oct 4, 2013, at 10:56 AM, Cory Smelosky <b4 at gewt.net> wrote:

=20
Yeah.   I know they're in the kV range. I'd appropriate discharge the =
CRT itself...but I lack the appropriate HV grounding wires.
=20

A flat-blade screwdriver and an alligator clip lead.   Clip the lead to =
the shaft of the screwdriver and to the metal chassis of the monitor.   =
Work the flat blade under the rubber cup where the anode wire attaches =
to the CRT.   Be prepared for a loud POP and a flash.

CRT is now discharged.

If the loud pop scares you, then you can build a resistor into the =
grounding lead.   I built one of these many many years ago, and it lives =
in my toolbox for just this event.

Please note that a discharged CRT can build up a static charge again =
just by sitting on a shelf.   Always re-discharge the tube when coming =
back to a tube you've left alone for a while.

Also, Brian's advice about the hand in the pocket is important.   Current =
is looking for ground.   If your other hand is holding the chassis, then =
the shortest path to ground is across your heart.   Not good.   =46rom =
your hand down your leg to ground, while not good, is at least not =
across your heart.

It was Dave's advice but I would have stated it if he had not.   In college,
a friend and I used to repair TV sets we found placed out for junk colection
and then, we'd sell them for beer money! ;)   I took my fair share of shocks.
One discharge was through my thumb and there's still a tell-tale mark there.

-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker       VAXman(at)TMESIS(dot)ORG

Well I speak to machines with the voice of humanity.