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Barco 808/Cine8

      >> Introduction 
      >> Layout and Setup Tips 
      >> Manuals / Downloads 








Layout and Setup Tips

 (Page 8)

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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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