Trick or fool DLP (SP4805) projector into thinking lamp is present.

[ChrisRR]

I realise this kind of question has been asked on and off and I find scattered reference to this kind of problem as applies to a variety of projectors. However, I thought asking was worth a shot as well as past discussions are partially related and scattered throughout time.

In my case I have a Infocus SP 4805 DLP projector. It has been purchased in order to experiment directly with the DMD array. The idea is to partially dismantle the projector and direct a variety of light patterns and signals onto the DMD array while applying certain video signals via the DVI interface.

Our lab doesn't require or desire the lamp running so I'd like to fool the projector microprocessor into thinking the lamp has started sucessfully.

So, if anyone has any information regarding the Infocus projectors, ballast, power circuits, manuals or service codes I would be grateful. Ideally a good idea of how to identify the various control/sense lines from the lamp to the micro would be great. I did email Infocus Tech on the remote chance they would help, but they were anything but as I expected.

Thanks!

[ChrisRR]

I'm working on the problem at the moment and so far I have performed the following two (trvial) tasks of disabling the lamp door microswitch and replacing the lamp thermistor with an equivalent resistor when it is up to temp (2-3 ohm). Next its trying to identify the various control lines fed from the lamp ballast board to the controller...I wish me luck.

[ChrisRR]

Ok, well it appears to have been easier than I had hoped. Pin 14 on the control lines (on the ballast board) goes TTL 1 (3.5V in this case) to TTL low (around 1V) when the lamp ignites. The solution is to simply earth the corresponding control line running to the processor in order to pull it low.

I can see the inverted video image on the DVD array so its all working at this point.

[OzOnE_2k3]

Hi, ChrisRR,

You can download the InFocus X1 service guide from the following site....

http://www.eserviceinfo.com/index.ph...X1serviceguide

The service guide doesn't contain full diagrams, but it does at least show the voltage levels needed when the lamp is ignited.

I'm assuming the Infocus X1 / 4800 is somewhat similar to the 4805 (I don't think it has 14 pins?) If things aren't quite the same as your PJ, the service guide may still be of some use to you?

I guess you've figured out how to bypass the ballast anyway though! Glad to hear the Infocus PJs are easy to bypass as I've just bought another Infocus 4800 which needs a new lamp - The 4800 arrived today incidently!

I noticed you have an optical bench in your photo and your experiments sound very interesting. I'll understand completely if you don't want to give anything away, but do you have any details on your project? Is it to do with modulating the light, or diffracting light somehow?

Please ignore the above paragraph if I'm being nosey!

[ChrisRR]

Hi OzOnE_2k3,

thanks for the link! Could we turn out to be useful. The DLP DMD arrays are amazing things which are finding application in all sorts of areas. Good eyes spotting the table, its part of a lab as you suspect.

[KABJJRB]

I have a infocus sp4805 and recently my color wheel ( i think )
is making a weird noise. my house is very dusty and i'd like to take it apart so i can check it out and clean it. the noise only happens sometimes but starts out pretty loud. i'm hoping i can get into the unit and fix and or prevent it from getting worse. could someone please reply or email me. thank you.

[victor-eyd]

Chrisrr,

could you circle the areas where the you described and perhap a before and after picture of your mod. I can't tell which board your describing, the yellow or the green one and where the you were able to fool the pj.

Thanks

Victor

[Hynotech83]

Originally posted by ChrisRR
I'm working on the problem at the moment and so far I have performed the following two (trvial) tasks of disabling the lamp door microswitch and replacing the lamp thermistor with an equivalent resistor when it is up to temp (2-3 ohm). Next its trying to identify the various control lines fed from the lamp ballast board to the controller...I wish me luck.

Hello Chrisrr,

Could you show where you set the resistor to replace the thermistor? Is that nessesary to fool the projector into thinking the bulb is there? And also what exactly does pin 14 do on the ballast board?

Many Thanks


John

[childsid]

CHRISRR,
Do you repair power supplies for projectors or know of someone in the States that does? I have boards for LP500/530, LP340/350, and boards for Proxima DP6155/Infocus LP690 that need repair. It's pretty steady jobs.
Mike Bates (MBATES) was repairing them for me and knows the method to repair LP530, LP350 as he has done about 50 of them for me but is too busy with other things to continue & I need to find someone fast to help me.
Thanks,
Jim Peters