3 lcd to led projector mod

[kobra000]

Hello all,

has anyone here attempted a LCD bulb mod/hack on a standard 3 lcd projector before? i have been reading on the subject for the past few days and it at least appears to be very simple...most of the source material i have ran across says this can be done simply by bridging or shorting the opto isolators on the power control board (depending on make/model of LCD projector sometimes as easy as shorting two small wires together) which will thus trick the projector into thinking its factory bulb is installed and thus allowing the user to install any bulb/optics package they choose.

What i writing this post for is because my electronics experience i guess could be best described as Novice or "hit or miss",sometimes things click easily and sometimes they do not! and the realm of opto-isolators is very new to me and i would greatly appreciate the input of the knowledgeable folks here on PL that i know for a fact have far more electronics experience and knowledge than i do.

What i am attempting this mod on is a Pana$sonic PT-LB20U 3 lcd projector with 1600x1200 res and a short throw lens system.I have the projectors service manual with full Block diagrams and schematics and have enclosed a snippet of the projectors power supply block diagram for those interested in helping.

any and all information,input,suggestions and creative advice is greatly appreciated

thank you in advance

Keith

[OzOnE]

Hi, Keith,

I know it's been a long time. I've just had so many things going on recently.

I didn't get chance to package up that driver board I promised you either - sorry about that.
I can send it to you as-is if you like? It just needs some of the transistors to be mounted to a heatsink properly (with the correct insulators / spacers).

I'll send it with the modded Ca$io driver board too. These Ca$io carcasses have been sat here for about six months now. I've kind of lost interest atm.

btw, that diagram is more of a "block diagram" than a schematic. Could you possibly post the circuit for the optocouplers (photo isolators) themselves?

The one main warning I'd give about bridging these things is to NEVER connect the high voltage ("hot") side of a coupler to the low voltage ("cold") side!!

(Worryingly, that block diagram seems to have the "HOT" and "COLD" labels swapped near the bottom-left! )

The whole point of the couplers is to send control signals between the mainboard and lamp PSU / ballast but without actually making a direct electrical connection.
I did this by mistake once because I was testing a ballast on it's own. When I replaced the lamp and switched on, it blew up and destroyed the mainboard / main ASIC!

Most electronic lamp ballasts actually "float" at a couple of hundred volts relative to (pos or neg) the main low-voltage boards.
(see that nasty 380V DC coming from the PSU at plug P2.)

Obviously this can make things potentially dangerous if you connect the wrong pins. With a diagram or optocoupler datasheet though, it's normally straightforward.

The optocouplers still work because the ballast side of the couplers just detect the light from the internal LEDs.

It looks like pin 1 of the control connector (A4 - bottom-left) is "L det" or "Lamp Detect"...
This is the only output from the ballast and probably all you'd need to do is connect pin 1 to ground (pin 3) at the mainboard end.

This should tell the mainboard that the lamp is OK or lit. It's probably safer to unplug the ballast from the mainboard, then just connect pins 1 + 3 on the mainboard itself.
Some projectors have more advanced signalling though - they won't always work by just grounding the pin, or they need the correct timing to keep them on.

Please post some close-up pics of the actual couplers on the ballast and the diagram for the ballast.


Cheers,
OzOnE.

[kobra000]

Hey ozone hows it going man...hope you and yours have been well.

yeah that would be great man..ill pm you my address.and its cool on its condition..just tell me where things need to go and itll be great.

think it would be kosher if i attached the entire service manual to the projo im trying to mod?...its kinda of incomplete i think..

but i can upload the circuit diagram for the ballast and P module (power module?)...i think im missing the one for the Q module ( controller module)

here is the file for the Ballast module



and the continuation of the ballast cuircuit file




ill take come close up pics of the actual boards very soon..i just gotta new digital camera and still figuring it out..

yeah i know what you ive all but given up on the Casio's but i still got a few ideas ive been toying with...almost got it to work with Zener diodes..but ultimately it failed.

yeah i was very itnerested in L det...think i should meter it and see how much voltage is on it before i connect it to ground?

if you could PM me your email add i could send the whole service manual to you..(one can never have to many service manuals lol) cause im not sure if it has the diagram for the controller module

thanks man i really really appreciate your help

sincerely

keith.

[kobra000]

let me know if those attachments are a no go..i used the snipping to to get them and i dont think it allows for zooming in on it...still trying to figure out how to post the PDF file straight to this thread.

[OzOnE]

Hi,

Yep, just give the L Det pin a quick test (between pin 1 and ground at the mainboard end).
Hopefully it will be floating at 3V3 or maybe 5V. If so, it might be best to put a low-value resistor between L Det and Ground (100 to 220 ohms, probably even 1K will work).

You should really unplug the ballast from the mainboard though. If the projector stays on with the resistor then it should be working.

Those diagrams are OK, but as you say they don't show the controller part. No to worry, the L Det pin must be the one you're after.

I'll PM my e-mail now...

Cheers,
OzOnE.

[kobra000]

OZONE..

Please let me know if you got the service manual i sent to your email. and if its good to go and not corrupted or anything..

thanks man

Keith.

PS ill be uploading High res pics of all the boards to that projector this evening.

[OzOnE]

Hi,

Yep, got the service manual OK. The files seem fine so far. I had a quick look at it...

If you open the "20print.pdf" file, it shows the ballast control socket (A4 on the mainboard) at the lower-left of page 8.

There are a few more input signals than I first thought, but you could still try Grounding the "Lamp Sense" pin...
Unplug the ballast control cable from the mainboard first, then join pins 1 + 3 of connector A4 on the mainboard.

If that doesn't work, then try Grounding the "Vdet" signal as well (pin 6 to pin 3).

Please be careful to steer well clear of the ballast / PSU though!

It shouldn't hurt the board to Ground those pins, they only have a weak pull-resistor on them normally.
(Obviously the other pins are mainly outputs, so you don't want to short them.)

I'll have to check through it some more but I'm a bit knackered tonight.
I'm gonna get an early sleepy now and I'll take another look tomorrow.

I'll let you know when I've sorted the driver boards and shipped them out.
(to confirm, this will include the pre-modded Ca$io driver with my LED driver attached, so no need to worry about bypassing your driver.

OzOnE.

[kobra000]

cool cool cool...

oh its ok dude..completely at your Leisure..i understand...please let me know how much shipping cost you and ill get it back to you somehow man.


thanks a million=)

keith.