VT100 Monitor Alignment Tool

tony duell ard at p850ug1.demon.co.uk
Sun Jan 18 13:31:36 CST 2015

> The horizontal width on my VT101 needs adjusting, so I am in need of a
> monitor alignment tool (PN 29-23190-00). I have tried searching the web to
> see if I can found out what they look like so that I can improvise something
> but I have failed to find a picture of the DEC one. Does anyone have a
> picture of one? Is it just a long thin screwdriver? Is it the same as a
> generic monitor alignment tool like this one:
> http://eu.suzohapp.com/product/H92-0196-00/universal-monitor-alignment-tool-
> kit? Even so the picture on that site makes it hard for me to tell what I
> need to improvise something.

Never try to adjust a ferrite core with a metal tool. You _will_ (not may) end
up cracking it and causing more problems. Not to mention of course, the fact
that the metal tool will affect the inductance anyway [1]. 

IIRC the width coil on the VT100 has a hexagonal hole in it. The tool is a plastic
rod with a hexagonal end (there are only a few common sizes). There is nothing
AFAIK special about the DEC one. People have made them by filing plastic rod from
a model shop or a plastic knitting needle, but I think you can get the right tool

[1] At one time there was a tool which consisted of a plastic rod with a ferrite slug on
one end and a copper slug on the other. Putting the ferrite slug into a coil increased the 
inductance, putting the copper slug in decreased it. So you tried each end in turn in a coil
if there was improvement you knew the coil was off-tune and which way to tweak it.


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