CurtPalme.com Home Theater Forum

Ben851 · Joined: 13 Sep 2008 Posts: 218 Location: Ottawa, Ontario

Greetings,

This got long really fast - as I've spent a few hours on this..
I'm hoping Mac will take an interest in this but everyone is welcome to provide suggestions!

On a whim I picked up an old Sony XGA LCD for $30. It's a VPL-PX11 and even came with the short throw lens... The lady who sold it said it needed a new bulb and she's at least half right. The bulb fires up and I get light out of the unit for about 15 seconds, then it shuts off and the lamp light goes on. I assume this is due to a dying lamp...

My original idea was to retrofit another metal halide bulb in to this thing, but since the other lamp still lights up and is reasonably bright, I wanted to try and bypass the fault detection circuitry and just run this lamp till it's truly dead.

I've managed to find three opto-couplers (Sharp PC123's) on what I believe is the power supply (Sony calls it the G board). I've tried grounding/shorting various pins on the low voltage side (5-7v) and have thus far figured out how to trip the ballast. I've also found one pin that if grounded after the bulb ignites, cuts the brightness in half, then completely kills the bulb, but leaves the projector running fine for approximately 30 seconds before shutting down. This is the closest I've gotten.

Problem is all three of these opto-couplers appear to be going the same way - i.e. none of them are feeding a motherboard or something with the results.

Mac, you wouldn't happen to have a service manual at your disposal for this particular beast would you? My guess at this point is that these three opto-couplers are for 3 individual tests, and they are feeding to a master gate somewhere that makes the final decision as to whether or not the system is good.

I've gotten the following readings off the three couplers' anode/cathode pins:

PH1101A PH1101C PH1102A PH1102C PH1103A PH1103C
ON 0.0 1.2 4.1 5.2 5.5 6.2
Off 5.5 6.2 6.2 7.2 5.4 6.2

Anyone have ideas?

**Curt Palme** · Posted: Sat Nov 20, 2010 3:22 pm Post subject:

I'm not sure if you'll find Mac here. His back went out about a month ago, and he emailed me and said he'd be out of it for a while. He hasn't posted here since from what I've seen. Get better Mac!

I wouldn't mess with this for a few reasons:

1) THe bulb can shatter, either taking out the optics or the ballast.
2) Check to see that the bulb hour meter doesn't need resetting, usually there's a secret code of keys to be pushed to reset it. A lot of units shut down after a predetermined time to prevent bulb shattering when people do reset the hour meter to keep using the same bulb. Then it explodes and ruins the projector. Wink

3) Check eBay for a replacement bulb, I just got one for a Sony 50" RP LCD for $75, way cheaper than I expected.
4) It could be unrelated to the bulb. A fault in a temperature sensor can shut down the set as well, etc.

Ben851 · Joined: 13 Sep 2008 Posts: 218 Location: Ottawa, Ontario

Hey Curt,

Too bad about Mac. I myself was MIA for a month or so - guess I missed that one.

I've already pressed the secret combo of buttons to reset the hour meter, had no effect... I can grab a full replacement bulb & housing for $140 brand new (non-OEM obviously).

I'm mostly doing this for academic reasons - I don't have a real use for an XGA projector other than maybe using it to get my geometry set up perfectly with my CRT.

I just went to an lighting store asking about metal halides to retrofit with and the guy said that the ballast must exactly match the wattage of the bulb (in the case 200W). I found this surprising - I would have thought that a 200W ballast would have had no problems lighting up a 150W bulb. My background is in PC repair, where a 350W PSU is 350W Max - not necessarily what it's putting out.

Maybe I'll give up on making this lamp work (no one wants exploding lamps!) but I'd still like to see if I can trick it into thinking everything is fine, and then I'll run some sort of halogen with an external power source..

**Curt Palme** · Posted: Sat Nov 20, 2010 5:42 pm Post subject:

Yep, what you're asking is beyond me. I know working on LCD backlights.. the sensing circuits are REALLY sensitive to overloads and open circuits... either one will cause the shutdown circuit to activate, so I think using the right bulb is crucial. Now, Sony should release the schematics (probably for some stupid price), but you might find one out there online for a cheap download.

tse · Joined: 03 May 2006 Posts: 1006 Location: Sweatbucket, Fl.

**AnalogRocks** · Posted: Sat Nov 20, 2010 6:28 pm Post subject:

macgyver655 · Joined: 22 Aug 2007 Posts: 7059

Im still here. Just not well enough to post much.

If you want t 0take the chance to play, here's what I got.

Look on the main board and see if you have an ic703. It would be a 120 pin chip, possibly number HD64F2633.

If so you want to find pin 21. You can try just lifting it first but you probably will have to ground it through a 100 ohm resistor.

Have fun.

Ben851 · Joined: 13 Sep 2008 Posts: 218 Location: Ottawa, Ontario

Thanks for the info Mac! I do in fact have that IC, I'll give that a shot. I also took Curt's advice and got the service manual for $8 online... It'll be a while before I can poke around with this again but I'll definitely post back with an update.

Take care of that back!

Ben851 · Joined: 13 Sep 2008 Posts: 218 Location: Ottawa, Ontario

Just an update for anyone interested - Mac is indeed correct. I grounded out pin 21 on that IC and the unit now fires up and stays up. The lamp still flickers off after a few seconds - I'm beginning to think this is just the nature of the lamp at this point. Now on to finding a suitable light source...

Thanks again Mac!

Jeremy112 · Joined: 28 Sep 2006 Posts: 1505 Location: Fond du Lac, WI

THis ties in with a projector a friend is going to mod for me with an LED to light it up since it lacks a bulb, the LED is a 2500Lm 30W White LED for $25, hopefully he can get it working because the LED would be better overall than a lamp.

WanMan · Joined: 19 Mar 2006 Posts: 9668

I'm curious to hear of the end results on this LED retrofit. For the life of me, I am surprised the UHP industry doesn't try to do this. Then again, many of the HT digital projector lamps are under $300 and being much less a recurring burden.

Ben851 · Joined: 13 Sep 2008 Posts: 218 Location: Ottawa, Ontario

I looked into LED... I don't think 2500 lumens is enough. Right now, I'm using a car headlight that runs about 1000 lumens (and terrible color temperature) and it's nowhere close to being bright enough. I've ordered an 11000 lumen metal halide bulb that I'm going to try and hook up to the PJ's ballast... I think when I fire that up for the first time, I'll be wearing body armor and using the remote... Smile

If we could find a way to concentrate 3 or 4 of those 2500 lumen LEDs, I think we'd get somewhere near the brightness level we need... but at $30 a piece, that's a bit steep for an experiment.

**Curt Palme** · Posted: Sun Dec 05, 2010 3:41 am Post subject: