Barco 500/800/801  

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Switched mode power supply

As with all Barcos, there are three separate power supplies on this board. The standby supply powers the IR receivers and CPU board at all times, and gives power to the red standby/on LED on the back of the projector.

The standby supply has one 125mA fuse on it that is hard to find at most supply places. I have used 250 mA fuses in its place, and have had no reliability issues. If this fuse blows a second time after replacement, there is a fault in the standby supply and must be sent in for repair.

The main power supply provides all voltages to the rest of the set, and is turned on and off by the standby supply. The main power supply has 8 fuses in total, all which are accessible by unscrewing the fuse holder tops. The fuse ratings are stamped on the heat sink frame, ensure that the right value fuse is reinstalled into each fuse holder.

The fuse pictured to the left in the above photo is the main input fuse to the power supply, and is a 3 amp. If this fuse blows again after replacement, there is a short in this power supply board and must be sent in for repair. The 7 secondary fuses can blow for no reason, and if your set runs fine after the replacement of one or more fuses, you can chalk the fuse failure up to aging of the metal element inside the fuse.

The third power supply on this board is the HTHD supply that feeds the HV and horizontal output stage. There is no separate fuse for the HTHD section. The green LED on the standby supply shows whether the HTHD supply is working. A short in the H output board will shut down the HTHD supply, as will a scan fail on either the H or V board (or if a yoke connector is unplugged). Generally the HTHD supply is more reliable than the main power supply portion of the set.