Notes on 9100 display - dimming away...

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I was looking at my display which had faded a lot recently and I noticed
that it is a vacuum fluorescent tube.

Now any of you in Pinball may remember that you can sometimes revive
fluorescent display tubes by over-driving the filaments so they glow a dull
red. Then I spent about 1/2 hour trying to find the pins. Finally on the
schematic (Service Manual Figure 7-2 page 1 of 2) I noticed that in the
upper right corner of the first page of the display schematic there was a
circuit that looks like a bi-stable flip flop that is computer controlled
and there were the six pins for the filaments. Then I looked at the back of
my display to find the same pins and looking in the immediate area noticed
that one of the two Zener diodes (surface mount) was missing. That was my
problem! Found it lying in the bottom of the cabinet - must have knocked it
off taking of/on the lid. Soldered it back on and the display returned to
it's former usable brightness.

There is a way to adjust the brightness as well. It is a setting - I think
you have to use a sub program to get at it, but you can adjust it. I just
forget how. Need to re-read the starter manual. When I find it I'll post it
here.

I have purchased a spare display tube for my 9100 though, I think it is a
good investment for it's useful life extension.

John :-#)#

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Received on Sat Nov 02 00:26:59 2002