I Googled a lot, and though it was a different brand, several people claimed on one of the projector power supplies, the big filter capacitors fail from being left hot in standby over long periods of time, and they may show bulging. Several people said they replaced them all, and it fixed it, not sure if it was the same PS or not.

That, at least the one we looked at, is a complex board with a microprocessor on it. That is hard to troubleshoot, at least without a software listing. Apparently the microprocessor decided when to turn the bulb on.

He took out the small PS board that supplies HV to the bulb.

On the supply voltage pins was a diode, which measured open as compared to an ordinary diode, but has a name we can’t find, something like T2d33. He thinks he will try a new diode, a general diode, and hope it works. If it’s a zener, well…

The only reason I am posting a comment here is to tell you, we started by looking to see what the parts on the board were. We found the PWM chip, and he identified a Toshiba microprocessor chip, 87c409bmg,and wondered what it was doing on a PS board.

Here right in your blog was the answer: looks at sensors to know when it is okay to turn on the bulb.

Cool!!! Thanks!

I assume that the prismatic lens thinger is the exact same thing backwards. I sense that I’d get into trouble if I dismantled the nearest projector to verify this. Would it be too much of an imposition to request more details?