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Barco 500/800/801
Horizontal Shift Board
As seen below, the H shift board has two sets of adjustments on it. The large
yellow coils are the H width/linearity coils. According to the manual, all three
coils should be in the full in (CW) position, then you start turning out (CCW)
the coils to the colors that are narrowest to match the width of each CRT tube
to the widest one. That way, one coil should always be in the full CW position.
You MUST use a non metallic screwdriver to adjust these coils. Due to the
current present in these coils when on, a metallic screwdriver will inductively
couple to the coil and get red hot as a result. Can’t find a plastic flat head
screwdriver at the local TV supply store? File down a chopstick, that works
well..:) (Note from webmaster: They're also available in a little $5 plastic
screwdriver kit from
Radio Shack. Ask for the "TV Tuning Kit"). Normally these coils don’t need
adjusting, but there are those of you that must tweak……
The above adjustments are far more important. These two trimpots are multi-turn
pots that shift the red and blue rasters left and right on the tube face. While
you also use the lens/tube toe-in on the tubes (see the manual for this
procedure), if the test pattern and raster isn’t centered on the tube face,
you’ll never get the toe-in right.
These two trimpots are multiturn pots, so one turn moves the raster of the red
or blue tubes a bit. Again, use a plastic screwdriver here, but if you must use
a metal small screwdriver, tape up the shaft so that you don’t short anything
out if the screwdriver slips.
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