Repairing LCD projector

[Mike]

I probably wont get an answere to this one either,

but.

I am repairing a sharp XG-E850U movie/computer LCD projector.

The ballast crapped out.

I am working on the ballast, and when the unit powers up, you can hear the
SMPS inside the ballast start up, or the high freq pulse.

But, the ballast will NOT pulse the bulb, and the open circuit volage on the
bulb is 0v. it will pulse to 2v and back to 0 when you first turn on the
projo.

The heatsink, when left on for a minute, will get too hot to touch.

IC1702, which has an odd number of 10T45 is the culprit of overheating the
heatsink, and the thermal relay will kick in, and shut down the ballast.

IC1702 drives the bulb's transformer. and I need a cross to the 10T45 IC.
Its probably a mosfet in a packege, but I need either a cross, or a pinout
of the IC.

The number on the board is K837IDE

The bulb is good, because it was tested in a friends projector.

Any Ideas? The 300+vdc source is on the ballast.

I removed the IC, and the ballast is pulsing, and lighting the arc. But the
IC is needed to put the bulb into run mode i guess.

 

[David]

Any reason you are posting three times over a couple of hours? One posting
is quite enough.

Your choice is to buy the service manual for the unit from Sharp and
troubleshoot the ballast assembly. oops, forgot, Sharp quit including the
ballast assembly schematic on some of these, the repair part is to replace
the entire ballast with one that has been rebuilt by Sharp for around $250.
On others the schematic was available, but some of the custom Sharp parts
were never made available as individual parts.

 

[Mike]

my mail server has screwed up, so i posted over at google, and it didnt show
at first.