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Lighting and OHP any lighting ideas and ohp info

DIY replacement lamp for projector
DIY replacement lamp for projector
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Old 18th October 2004, 02:22 PM   #51
Tuga is offline Tuga  United Kingdom
diyAudio Member
Join Date: Mar 2004
Location: Hampshire

That I would also like to know….lol.
I tried with a dichroic halogen bulb 250w with a external PSU (to big about 600W)
And the picture was acceptable, but I had a IR filter right next to it and the bulb didn’t like it and died after 10mins...

I will try fitting an Osram HQI-T (85mm long) to a par20 reflector and see how it goes.
I have not tried any optics or light engine set up yet so I am not the best person to ask.

I think the ones who can help you /me on this are, Mathias, Ace and Tiarb. (no disrespect to all other great minds on this forum)
Tiarb as done it and tried a few options so make a search for posts from Tiarb.
There is really useful info on them about retrofitting.

I still have to wait a few weeks before I can order the da** lamp.

Please let us know how it goes…

PS: Slickwillie, U don’t know how RELIEVED I am to ear from you again….lol
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Old 18th October 2004, 02:56 PM   #52
auz_mo is offline auz_mo  Canada
diyAudio Member
Join Date: Jun 2004
Location: Sudbury, Ontario
Default FOR SALE

I have a light, a ballast and a socket for sale, its a brand new 400 Watt Metal Halide bulb, socket and ballast, I have an extra one from a project I was going to try with two bulbs, its never even been used, BRAND NEW!

I still have the reciept for it all at 182.34 CDN, its all high quality low-noise stuff, I want 150.00 CDN for it all, make me an offer if you don't think thats reasonable.

Let Me know at this email address: j_osborne@unitz.ca

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Old 18th October 2004, 04:06 PM   #53
Andres is offline Andres  United States
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Join Date: Nov 2003
Location: Miami, FL
This setups look very promissing (although I dont think they are cheap)



I've contacted this company to try and get a price quote. Look at he color temp, 8500k for the SHP mercury and 6000k for the MH.
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Old 18th October 2004, 04:38 PM   #54
Andres is offline Andres  United States
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Join Date: Nov 2003
Location: Miami, FL
The company is going to receive those products next week, so they wont have a price until then. I hate waiting. Patience is a virtue I wish I could buy somewhere. :-)
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Old 21st October 2004, 09:06 AM   #55
Tiarb is offline Tiarb  Finland
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Join Date: Jul 2004
Location: Pukkila, Finland
They are very likely very very expensive products.... 4 example osrams 150w HQI-R bulbs (similar to those that were behind the links, MH's with built in reflectors) WITHOUT ballast/electronics.... 180 euros....

my stuff is at http://tweaknmod-av.tk
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Old 26th October 2004, 04:25 AM   #56
Bruwed is offline Bruwed  Australia
diyAudio Member
Join Date: Oct 2004
Default Lam\ps and replacements

To answer some the questions that have apperaed on this forum and give my bit of info:

Firstly, the reason that the MH and UHP lamps have a small electrode gap is so that the light can be spread evenly by the lamp reflector over the required area. All that does is provide an almost parrallel light source through the rest of the optics to the LCD screens.

So there is nothing magic in using a point light source and no reason why any other light source cannot be used.
The difficulty is obtaining an even light spread of a constant light temperature.

Secondly, I have been using street light MH inner lamps in one of my projectors for several years now. These are quite cheap to purchase and have an expected life of 10000 hours, but, they do have their own problems. Most are AC types and so the electrodes are equal in size.. If you are going to use them on DC then you will have two problems - one, one electrode will overheat - two, there will be problems with chemical reations at the hot electrode. I f your projector has a DC supply for the lamp, it is better to obtain the DC types in which one electrode is much larger than the other.

For every one that I have tried, I have carefully broken the large outer glass cover and removed the inner quartz bulb. Using linen gloves to handle it, I have then glued it in place in the glass reflector of an old projector lamp, using muffler cement. The correct location to give a fairly even light output can be seen from the front by looking at the image in the reflector surface. It must be evenly looking at the electrode gap.
There will probably be some extra leakage light from the rear of the centre of the lamp holder so make sure that you use enough muffler cement back there to block this.

Now without the outer protective glass envelope the lamp will output a lot of UV. So be careful and do not look at any leakage light when it is use. Also make sure that you UV filter between the lamp and the LCD screens is in good condition. Otherwise you LCD screens will gradually deteriorate.

Thirdly, regarding the ballasts for the lamps: all have current limiting device in them since all of these HID lamps are inherently negative resistance types. SO you will not overload the ballast from a current point of view. But, and this is important, different types of thes lamps have different gases in them ans os the operating voltage for the arc will be different. This is where you can overload you ballast. If the normal lamp draws 4 Amps at 30 Volts across the lamp then that is what the ballast has been designed to accomodate. But if the replacement lamp has more or less voltage across the arc when running then you can either overload the lamp or the ballast.
In addition, the high voltage need to get the lamp to start arcing in the first place will depend on the gases used as well as the electrode construction. Some lamps will not strike because this voltage is too low. Now many street lamps have an extra electrode to asssit in lowing this striking voltage. Some even had then externally wrapped around the unner bulb near to the opposite electrode.
So you have to be very careful in changing the type of lamp. But it can be done.

Forthly, the actual light output that you will get on screen will probably be a bit less than the equivalent normal lamp. This is due to the difficulty in aligning the new lamp to give full light output. There are a lot of losses along the way for older projectors wheras the later types have btter optics. In all cases though LCD screens tend to lose about half the light from the lamp.

Finally, for all those people trying to use LEDs, keep going and do not pay any attention to the negative people. I too have tried using LEDs - 100 of each of red, blue, and green - but have not had much success. The distribution of the light was too uneven and the colour temperature was not only uneven but also variable from one day to the next, even with current control to each group of colour LEDs. The light output was not as high as it needed to be and only produced an apparent light output of less than half of the normal brightness of the normal 1000 lumen lamp.
I suspect that the heat from the very closely matrixed LEDs was affecting the output of the individual LEDS. For reference they were obtained from Hong Kong via eBay and the red LEDs were advertised as "typically 20,000mcd" output.
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Old 11th November 2004, 07:11 PM   #57
Tuga is offline Tuga  United Kingdom
diyAudio Member
Join Date: Mar 2004
Location: Hampshire
I'm trying to start a new thread but get the message:

"please search the forum before posting"

and wont let me start the thread anyone knows what's happening?

By the way, how do you post more than 1 pic in the same post?

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Old 15th June 2005, 10:13 PM   #58
shlomid is offline shlomid  Israel
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Join Date: Jul 2004
Location: Israel
Thumbs up thanks!!!!!!!

Thanks Thanks Thanks Thanks
Thank you Tuga you are the best!

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Old 4th July 2005, 04:51 PM   #59
anthp is offline anthp  United Kingdom
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Join Date: Jul 2005
Location: north yorks
Default 18 wheelers Lamp and balast, dlp

I want to use this lamp for a dlp projector I think with the colour wheel I could get problems with interfererance with 50hz like a raster line if I use a transformer type balast. I think a high frequency or DC is needed the balast in the picture looks like a high frequency switch mode supply i think this should be ok

of course I could be totaly wrong

any ideas on this would be good
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Old 22nd August 2005, 08:30 PM   #60
jamesbeat is offline jamesbeat  United Kingdom
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Join Date: Aug 2005
hi, i have been reading this thread with great interest. i am trying to replace my projector's lamp with a cheaper one.
i thought i had worked it out, then it turns out that some (all?) projectors use uhp lamps which are dc as opposed to ac for mh!
i have two projectors which i bought off ebay very cheap- a liesegang dv290 and a 3m mp8640. they are actually the same projector marketed by the two different companies (the hitachi cp-l850w is also the same)
i bought the liesegang partly because it was cheap, and partly because it is old and big, reasoning that the older and bigger it is, the more chance i have of retrofitting the lamp successfully.
i got the 3m because it was dirt cheap (won't power up) and because if i manage to work out a lamp arrangement that works, i can just duplicate it on the other machine (cinema in the bedroom too!)
anyhoo, the user manual for these machines states that the lamp is 260w metal halide- does this mean that the lamp is definately NOT a uhp lamp, or are uhp's a type of metal halide?
i'm guessing that it's a normal metal halide lamp, as it's an old machine (presuming uhp's are the latest technology). when i take the lamp out of the reflector, i'll be able to get a good look at the electrodes- i believe they are different sizes for dc (uhp) and the same size for ac (mh) is this correct?
as far as i know, mh lamps need their rated current +/- 10%. if this is correct, a 250w lamp powered by a 260w ballast should be fine.
could anyone who knows about these things check the above and tell me if i have made any mistakes before i blow my lamp/ projector/ self up?
if i get this to work, i'll write a nice detailed description of exactly what i did and how i did it, as i can't seem to find any posts from people who have done this
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