Help with electronics troubleshooting on projector

Can any experts help guide me through electronics troubleshooting on a broken projector?

A fan on my InFocus LP130 projector is not working, which likely caused an overheat and broke the lamp. Yesterday, I turned it on and off a few times and saw the fan spin for 1 second before stopping. Today, I turn it on and the fan doesn't spin at all.

I used a voltmeter and read 0V at + and - terminals on the fan. At the other, similar fan in the unit, I read 9.5V. I want to check the header on the PCB where the fan connects, but I can't (yet) get the case open.

So, I'm suspicious: Is the fan dead, or is something else not getting power to the fan? It spins, like I saw yesterday, so it must work. And, shouldn't it be getting 9V at its terminals even if the fan was dead and unable to use those 9V?

Before I order a new fan, I want to be sure it's that simple and not a bigger problem that's beyond my ability. $20 fan sure beats $2000 new projector. Thanks guys!

Clearly you're not trying hard enough. :-)

Opening it is easy. Its being able to put it together again afterwards that is the hard part

If the voltmeter reads 0V across the fan then either its not getting any power at all or its shorted out.

It's quite possible the fan is temperature controlled, so might only spin when it thinks it should spin.

Also it's possible/probable that it uses PWM to vary the fan speed so it only runs as fast as it really needs to.

I got the case open, saw 0.02V on the fan header, saw the fan work when connected to the other header, and determined that the problem was beyond me. Before closing it up, I installed the new lamp, which I had confirmed as working on Thursday. Now I turn the projector on and get nothing. Maybe my fiddling broke it worse.

Or maybe it's something else. When I turn it on, I see and hear a metallic disk spinning up*. 20 seconds later, it spins down. During normal operation, this disk must have remained spinning because I recognize the whine that it makes. It seems like the projector knows something is wrong, so it quickly gives up.

Maybe Shonky's right and a temp sensor is bad, so the front fan and the lamp don't turn on. At 6 years old, that seems likely; but the projector has only 420 hours on it. The old lamp shows no sign of being burnt out.

Maybe there was nothing wrong at all; when I replaced the lamp, it worked, and that burning smell was normal. Then I messed with it and broke it further.

Regardless, I bought a new one. Does anyone know of a projector repair shop who would actually look at this? Too often, I send things to these random Internet repair places and they come back still broken.

Thanks for your help.


* This is a DLP projector. So, that spinning metal disk holds the image which is projected? And it spins so that it's not sitting idle in front of the burning lamp? Because by spinning it, the image is in front of the lamp only 1/5th of the time and thus avoids getting burnt out?

If it is a single chip unit then the spinning disc is probably the colour wheel.

Scratch all that. I found a kill switch preventing the thing from running with the front panel off. Pressing the switch, it works with the new lamp and the front fan runs (after shutting off shortly after power on). With the old lamp, the disk spins for maybe a minute, the front fan turns on and off twice, and the disk spins down.

It's that burning smell that caused this whole investigation. Maybe that's normal for a new lamp; a break in period. I just don't want it to overheat and break another $300 lamp.

Thanks for your input.

Was the new lamp clean? Did you touch the glass with your fingers?

I would assume projector lamps would have similar issues to halogens (if they aren't actually halogen).

That burning may be something on the lamp or some protective coating. If the burning smell was normal I'd expect a note in the install instructions about it.