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.

 

[James Sweet]

"Mike" <mbates17@cinci.rr.com> wrote in message
news:c9d5d577.0403061047.b96a37c@posting.google.com...

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 would check for bulging or leaking electrolytic capacitors, and check any
diodes to see if they're shorted, beyond that it's hard to say without
looking at it. Transformer or the IC could be bad too.

 

[JabbaThe Hutt]

James Sweet wrote:

I would check for bulging or leaking electrolytic capacitors, and check any
diodes to see if they're shorted, beyond that it's hard to say without
looking at it. Transformer or the IC could be bad too.

Now thats the pinnacle of expert advice. I have my kids do that for me.
Then I "look" at it to see if there's a bad transformer or IC.

Jabba