Layout and Setup Tips
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Barco 70x machines are a bit different from the other models of CRT
projectors. While the circuits of the 70X series are loosely based on the Barco
800 and 801 series of sets, the layout is different, and very few parts are
compatible with other Barco projectors.
All LED’s in Barcos are color coded.
Green = good and indicate a normal operating
Red = bad and indicates a problem. A red LED that is on may not
indicate an actual fault, it can indicate a lack of sync or signal, but in
general, all red LED’s should be off when the set is in operation and has a
video signal fed to it.
Internal layout of the 70x series
(Thanks to Filipe Coutinho for the photo!)
Switch Mode Power supply and HV section
Let’s start with the 70X series power supply board where a lot of failures
occur. This power supply is located under the lenses behind the plastic cover.
Remove the two Philips screws and take off the plastic cover. If the set has an
IRIS on it, remove the wire going to the IRIS at the IRIS. The power supply will
then pull out from the front. Note that there are a number of wires that connect
the power supply to the rest of the set, and they can snag on the chassis when
you pull out the supply. Unlike other Barcos, the HV supply, SMPS and AC input
board are all located on this board. The circuits are similar in design to the
800/801 series, but the layout of the components is completely different from
other Barco sets.
The above pictures are from a later model Barco 708 projector. The older sets
had a single jumper wire in place of the 110/220 volt jumper. To set the older
sets to 220V, simply cut the jumper wire on the board. For 110 operation, the
jumper wire must be in place.
There are a series of DC fuses in the unit. The older projectors had clip in
fuses that were removed with needle-nose pliers from their fuse-holders. As with
other Barco models, many of these fuses were sand filled (explosion-proof
fuses) that have to be checked with a continuity tester. The later model sets as
pictured above had these fuses soldered into place and are called Picofuses.
These fuses are found at a good electronics parts store (Radio Shack won’t have
There are two more fuses right behind the left fan. One is a 2 amp fuse that
feeds the HV section, the 3 amp fuse is the main power supply. One last fuse is
a 1/8 amp that feeds the standby power supply that powers the CPU board and the
remote sensors. As with all fuses, replace the fuses with the correct value. If
the fuse blows again, there’s a problem in the set. A larger value fuse will
make whatever short is in the set worse. There are two fuses right behind the
power cord inlet. These are the master power fuses, and do on occasion blow for