Mitsubishi DLP Color loss (update)?

[zinda]

I have a hand me down 73" with the typical color problem and have been reading the posts about this and how to find or solve this. Just as others after the set is on for a while the colors go into a change period then drop out. After reading the Plain Bill post on what his findings were, I went ahead and tried a few things myself with nothing really to lose but the $20 for gas to get it. I hacked a 120mm fan onto the metal cage that shrouds the color sync assembly board "PMW" I believe. It had the 80mm thin fan blowing into the board area. Turned it on with back cover off and within 15 minutes it started to act up. I left the cover off and aimed a small 120vac personal sized fan 6" at the open back and left the colorless set on and within 10 minutes the color was restored without ever turning the set off! Now what I need to know is if I should turn the 120mm fan backwards to suck the hot air out of that shroud and duct it to the back cover? I think that the heat is blowing into that shroud and is pushed out into the chassis area where it is causing a build up of heat around a more sensitive component, (lightwheel, or some controller there of). Seeing how it was able to restore the color just by a small air movement aimed randomly at the back of the set I am lead to believe that this may cure it but I'm going to try that right after I'm done posting, the other question - are there any ports or places on any of the boards that I could safely connect another fan that draws up to 0.12amps to support another 120mm exhaust. The 80mm is rated at 0.09amps and have no problems running the 120mm but I tried a 3 speed switchable fan first and the tv didn't like the high setting and shut down, so it was removed. So I do know that I'm current limited at that source. After a brief look at the skematics I saw that there may be unused fan ports on 1 or more spots due to the models but not sure if the 73" has both the smaller versions boards plus the 73" extras or if they have completely different board styles. The drawings show areas that are for 73" only but don't exclude many of the smaller sizes areas when dealing with the 73". If this makes any sense. Sorry for the long post but I'm very close to solving this, I had no problems for 24hrs after I used the small fan. I'll be back to post the reverse fan results in a few hours.

[PlainBill]

Re: Mitsubishi DLP Color loss (update)?

I had assumed that most of the components were on the underside of the light engine. When I did learn that virtually everything was readily accessible I already had a replacement light engine. Thus, I didn't get an opportunity to troubleshoot to the component level.

If ever there was a problem that begs for the use of freeze spray and a hair dryer, this is the one. It should be possible to identify the offending component.

If you get the opportunity, I would love to see a picture of the circuitry under the cover.

PlainBill

[zinda]

Re: Mitsubishi DLP Color loss (update)?

i'm getting a temp sensor (infrared) so I can find local temps inside the back area and find the hot spot to figure an exhaust route to be ran by a 100vac fan that I will turn on with the set via relay. send pictures next time as i go trough the process, but I found so far that reversing the new 1200mm fan did not provide a full fix and also cleaned the screen behind the fan for the color wheel assembly. I noticed that this fan had shown a flaking label looks like it's really dried out and stated to come off. I regreased the fan and recovered it with foil tape with a crazy glue covering to keep it in place. I also turned the entire memory assembly 180 deg so the fan exhausts to the back cover instead of into the set. I realize it will now be drawing air from the hot inside area but I'm sure that it isn't hot enough to make any problems. these changes have made marginal advances without the external fan it still eventually will lose control of the colors but not to the point that it turns black and white.

[zinda]

Re: Mitsubishi DLP Color loss (update)?

I'm sorry but I've been wrestling with the TV and then trying to get good shots with any of my numerous oldish digital cameras has forced me to move on without pictures but I do have positive permanent results. I ended up changing out the 80mm fan that cools the engine board to a 120mm and cut the shroud away to do so. Added a new cardboard duct to the back panel. I used the original fan connection but had to switch the wiring to match. I swapped out the connector from the 80mm. I noticed that the 73" model has 2 exhaust routes but has no fans in them, so I set 1 80mm in each side forcing air out the sides I used a little foam rubber around the fan cases to help quiet them & close the gaps around it for better flow. I also removed the piece of metal that is directly above the lamp to let air flow out of that area with the help of another 120mm fan installed in the bulb change route. It's a plastic tunnel that has a sticker on it with a warning list for bulb replacement. I removed that label and mounted the 120mm fan on that removable piece so it draws air into that area towards the bulb and out the side duct. To run the extra fans I used an old Computer Power Supply the kind that has the switch wired to it (they can turn on without a motherboard). I mounted it in the lower right hand corner if your looking in the back, I removed the cover and screwed it onto the plastic above the balist box and discarded the balist plastic cover. I used the PSU's fan mounted by an bracket that scres onto the right side and holds the fan against the back cover where there is a louvered opening. this is to cool the PSU (I doubt it is even getting warm but I also need the air flow in that area to push the hot air from the balist and force it out the side duct. My set has been on for 3 days now and All is well, I'm letting a DVD play at 1080i over and over without fault through the hdmi port input. the picture is fantastic and the hours I spent soldering extension wires onto a pile of my old fans turned out to be well worth it. This cost me $0 and I'm sure most everyone has these Items laying around but it will cost only about $50 to buy with the power supplies found at any thrift store but they are getting harder to find without buying an old tower, usually $9.99 and it will likely have 2 or more fans to apply also. I would look into getting higher quality and quiet low noise fans if you are thinking about this mod. my Tv sounds like an old tower set up with the jet airplane start up.

[PlainBill]

Re: Mitsubishi DLP Color loss (update)?

I neglected to post the final update on the original thread. I just did that, and my results indicate the additional cooling is at best a temporary fix. Certainly it was in my case. Over the course of the summer of 2009 additional cooling (higher fan speed) became necessary to maintain proper operation.

Over a year ago I replaced the original light engine in my TV with another one. It's been working perfectly for over a year with no additional cooling.

By the way, what model is your TV?

PlainBill