 Barco 808/Cine8
Layout and Setup Tips
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9) AC input board:
This board contains a voltage doubler
to convert the 120 volts AC to about 300 volts DC to
feed the main power supply. The 120/220V jumper is also
located here. There are two main fuses near the bottom
of this board.
AC input board. The two main fuses on this board blow
from time to time for no reason. Unplug the projector,
pull the board out and you’ll find the fuses at the
bottom of the board. Check each one with a continuity
tester. Once in a while the 110/220V jumper will develop
a bad connection on the pins. If the set goes on and off
intermittently, check for arc marks on the metal pins
coming out of the board. One last source for
intermittent power problems on the set are bad fuse
holders. If one fuse holder end is darker than the
other, then it’s possible that that fuse holder has a
bad connection due to overheating and corrosion.
Replacement is the only option here.
10) EHT board:
Also known as the high voltage board.
Works in conjunction with the HV quadrupler to provide
the set with 35Kv for the tubes, and 12,000 volts for
the focus and master brightness circuits. Has a number
of sensing circuits on it to protect the set form over
and under high voltage conditions, and will shut the HV
down if an overload condition is sensed.
The EHT board generated the pulses that feed the HV
quadrupler which then generates the high voltage needed
to power the CRT’s and the lower HV feed to the focus
block which also in turn generates the G2 (brightness )
voltage. The EHT board, quadrupler and HV splitter all
work in conjunction with each other. A failure in any of
these can and will usually trigger the EHT shutdown LED
as indicated on the board. The only user serviceable
part on the EHT board, quadrupler and HV splitter is the
fuse on the EHT board. DO NOT go adjusting the trimpots.
Serious injury and imploding tubes can result, not to
mention excessive low level X ray radiation if these
trimpots are misadjusted. If the fuse blows a second
time, the EHT board is bad.
Note that if the EHT red LED is on, the problem can be
the EHT board itself, the quadrupler or the splitter.
Short of replacement, there’s no way of telling which
component is bad.
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