Panasonic PT-L711U Projector Lamp Hacking.

Hardware related mods, hacks, questions and ideas.
Jarod
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Panasonic PT-L711U Projector Lamp Hacking.

Post by Jarod » Wed Nov 30, 2011 1:18 am

A friend of mine asked if I could figure out some way to solve his "Replace Lamp" Issue on his Panasonic PT-L711U Projector.
Buying a new lamp is too expensive ($170-200)
So we're looking at alternatives such as an LED array or halogen headlight, work light or other option.

While I'm not entirely sure if we'll find enough output from any of those kinds of bulbs there is a larger problem at bay... The projector will not stay powered on for over 2 minutes unless a working blub is attached. This "Safety" must be bypassed (As most safety's usually require)

So here is my findings:
First pic shows where we need to be looking at.
Second shows the pins we'll be working on.
3rd shows a closeup of the pin that needs to be grounded, It is a 6 pin connector, the white wire farthest on the left of it has 5v on it when the lamp is not operating and 0v when the lamp is functional.
4th shows the finished product. (Its not pretty I know. Need more practice soldering :P )
Attachments
IMG_5710.jpg
Circled area is where we'll be having fun XD
IMG_5713.jpg
Connect Far left on 6 pin connector (White Wire) to middle pin on 3 pin connector (Black Wire)
IMG_5714.jpg
Ground the circled pin.
IMG_5718.jpg
Done.

foxmiles
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by foxmiles » Wed Nov 30, 2011 1:42 am

Here are a couple chassis mount led's. There are more chassis mount and lower power smd's available. The cool white's (5600K) are brighter than the neutral (4100K), but you need to find the color of the projector bulb. Both are available in cool or neutral, 12v or 16v cool/18v neutral for the higher power one.

You would need a constant current regulator (not hard to build) and a heatsink of some sort.

I don't know if they would fit in the housing or not. I also don't know how much light you will loose before it leaves the projector.

I'd go with the bigger one if 18v/2A is available, it's not hard to make less light. If 12v/2a is available I'd try that before making big psu changes.

19mm neutral white 1530-2601LM 1-2A @ 18v - $16.26
http://search.digikey.com/us/en/product ... ND/2331643

19mm cool white 1320-2244LM 1-2A @ 12v - $10.83
http://search.digikey.com/us/en/product ... ND/2331633
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Jarod
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by Jarod » Wed Nov 30, 2011 2:06 am

According to that, with the bigger unit at 25C I would get around 1500 Lumens?
Theres fans blowing air across the bulb constantly so it should stay pretty cool, although perhaps a heatsink would be a good idea, every led projector has a heatsink (diy led projector repair)

I'm not entirely sure what kind of power is available inside the unit, the OEM bulb is a high voltage Halogen bulb or something (Nearly fried my multimeter finding that out, made a really nasty arcing sound inside of it)

I know there is 2v, 5v, 10v, and 15v, how much amperage we could pull off of one of those your guess is as good as mine.

I should check what the actual power supply puts out too.
I'm thinking an external supply might be needed to get enough voltage without blowing fuses inside the projector.

I've got a good 3x3x5 inch spot to work with, the light was 3x3 square approx, and 5 inches long for the cage and everything it was in.
I'll talk to brandon and see if he wants me to buy one of those arrays and give it a shot

Jarod
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by Jarod » Wed Nov 30, 2011 2:27 am

looks like cool white would work the best

this page says that projectors usually run between 5500k and 9000k

the cool white bulb puts out 2200 lumens and is 5600k so that should work, maybe a tad too warm color wise but i don't think its that bad. they say warmer colors work better for movies anyways.

now comes the question, how can i hook it up and how big a heatsink do i need to put on it?

foxmiles
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by foxmiles » Wed Nov 30, 2011 2:54 am

From my skim of the datasheet they are chassis mount - you bolt them directly to the heatsink with thermal compound (probably drill and tap the heatsink). Then mount the heatsink where you need it.

A constant current regulator assembly for this should be 2-3x to-220 sized chips, couple little resistors, one or 2 trimmer pots, one big resistor (say 5-10w 0.1-1.0ohm) couple small caps (10uf or so), possibly an op-amp (probably way less than this, building a variable voltage and current regulator in my head). It would regulate the voltage to set the current, so higher voltages (20V) input would be ok. Should fit in a very small space, the big chips should get some airflow.

The math is in the datasheet and I'll check it if I can figure it out, but I'm thinking something like a 686/k6-2 sized heatsink (2x2x0.5 should be plenty with a fan) - if there's a fan in the case will help and one mounted on the heatsink would be really good. I think there's some leeway here, especially if you have a fan blowing directly over it.

The bigger one in cool white would do 2000lm@1.5A/16.5V with the case @ 60C - $16
http://search.digikey.com/us/en/product ... ND/2331635

If you get the go-ahead I'll figure out a CC regulator with specific parts. I think I've got an old heat sink or two lying around, though you probably do to.
Digging with a spoon will accomplish more than leaning on a shovel.

foxmiles
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by foxmiles » Wed Nov 30, 2011 4:00 am

Grab an lm350 and a 0.82ohm 5w resistor (these will make a really simple constant current source of 1.524A) we can just dead-bug it behind the heatsink or something (will need airflow)
http://search.digikey.com/us/en/product ... -ND/458688
http://search.digikey.com/us/en/product ... 5-ND/18629

a 0.5ohm 5w resistor (provides 2.5A, we can make it adjustable if we need to modify the circuit)
http://search.digikey.com/us/en/product ... -ND/595532

should be less that $3

http://www.zlgmcu.com/on/ds_ldo/LM350-D.pdf - figure 24

If I think of more I'll let you know
Digging with a spoon will accomplish more than leaning on a shovel.

Jarod
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by Jarod » Wed Nov 30, 2011 11:10 pm

So I bought the LED array, reflector and all the components you suggested, Digikey has so much stuff!

I've also ordered a little bit of stuff for myself (may as well combine shipping costs right?)

I tried as a proof of concept an array of 6 super bright white LEDs I scrounged from some goofy battery lamps.
It worked fairly well in a dark room, but was obviously not bright enough for use if there was much light at all.

I decided to attempt a more permanent mount for the 6 led array, busted out my soldering iron and got the circuit mixed up in my head and burned out 2 of my leds :(

But anyway I'd say as long as we're around 1500 lumens or above we should have plenty of light for normal operation.

foxmiles
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by foxmiles » Thu Dec 01, 2011 12:35 am

Yea, they have a LOT of stuff. I got a relay for a furnace board for Dad - new board=$100, new relay=$3

We'll have to try to not burn out the $16 LED. We'll power it up slowly on the bench and monitor the heatsink temp. It should consume 25W or so and a few watts at the regulator. We'll also confirm the regulator is regulating.

Are you sure you burnt them out? Usually that takes an over-voltage condition. They usually survive being put in backwards.

I love trying to get a circuit right in my head, I blew up an IC and a transistor building my bench power supply, then had the voltage regulator in backwards on my ESR Meter, it survived, probably because my PS was doing the regulating. Fortunately I bought enough to do 2 of each, so I can build another ESR meter, except for a few components I ordered the wrong values of...

On a related note, if you're going to be doing much circuit building a current and voltage regulated power supply is a really good first project.
Digging with a spoon will accomplish more than leaning on a shovel.

Jarod
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by Jarod » Fri Dec 02, 2011 2:50 am

foxmiles wrote:Are you sure you burnt them out? Usually that takes an over-voltage condition. They usually survive being put in backwards.
I'm pretty sure... Soldered the power lead on the wrong side of the resistor... 6v into a led designed for around 3... one led lit up really bright for a couple seconds, then started to crackle and made more of a reddish light instead of the white its designed to... and the 2nd one lit up and didnt seem to be blown until i corrected the power lead and it did not light up anymore.

Yea, I should build a power supply, I'm making good progress on the cnc machine, made several modifications with some scrap metal and improved the rigidity today... which sadly meant all my holes were drilled in the wrong spot so i had to re-drill everything. x axis is nearly done, i still need a table for the y axis and the z has nothing yet. but it'll come together quickly.

now all i need to do is build a controller and find 2 steppers that are strong enough to move the parts.

foxmiles
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Re: Panasonic PT-L711U Projector Lamp Hacking.

Post by foxmiles » Fri Dec 02, 2011 1:46 pm

Ah, Yep that will blow them.

Edit - remainder was irrelevant to this thread and belongs in a different thread
http://www.trythistv.com/viewtopic.php? ... p=113#p113
Digging with a spoon will accomplish more than leaning on a shovel.

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