Dim Mitsubishi WD-73738 DLP Telivision

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

Thanks guys! It's not my TV, just one a guy brought me to fix. Pretty good gig right now. He brings them, I fix him (he pays for the parts), he sells them, we split the profits (minus price for parts). Working pretty good right now. Lot of work, usually easy fixes, but now we get some Samsungs that are not so easy to fix. Beautifully built, but hard to diagnose.

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

Added note, the mits laservue sets use a dlp chip in the design.

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

my oops... my description was more for the samsung dlp design.

Spark_shivago, the dlp chips used in most of the affordable 4k projectors are not 4k "mirrors on a chip". the system use a "wobble" system to move a given mirror in 4 directions such that there are only "1K" mirrors. In the samsung RPTV dlp, it is only "512" mirrors which are "wobbled" in 2 directions. The "wobble" can be done fast enough during the picture "build cycle" such that the viewer basically sees 1k or 4k depending on design. Lots of discussion on the pros and cons of the display system in various forums on the networks. Basically, the "wobble" allows for small chips and those a cheaper production design along with other things.

Anyway, enjoy your RPTV since it is unlikely that they will ever produce a "new version" again.

[R_J]

Re: Dim Mitsubishi WD-73738 DLP Telivision

The laser rear projection tv's don't use a dmd chip, consider it to be similar to a crt but instead of 3 (rgb) electron guns scaning the phospher screen you have 2 or more laser's of different color scaning a screen.
Hisence has a 100" laser http://hisense-canada.com/laserTV $9,999.99

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

:-) you got the wrong model mits.... you need a laservue one.

Anyway, it is not a "simple" light source swap... the light engine does not have a color wheel because the "bulb" was replaced by three color leds that flash like a "fake" light wheel. Its disappointing that both mits and samsung abandon the design. People wanted "flat thin" that could be hung on a wall for "sexy". Ultra short throw projectors (front) are still alive and DLP continue to be one of the main stays even with 4k. They are just starting to roll out "affordable" laser / led based units (low powered / light output leds have been out for a bit).

I did not know laser / LED based units where available. That is amazing, they can do 4k with DLP technology. Even the 1080 impressed me. That's one little tiny mirror per pixel, correct? So over 2 million mirrors in a little tiny chip for this TV. Insane!

And yeah, it seems people want thin right now. I've seen on Samsung's site some of their new Always-On TVs, where when you're not watching TV, the TV looks like a painting or something just hanging on the wall. Kinda nice I guess, but more money than what I got for a TV!!!!!

Friend of mine had a real nice DLP projector, 1080 hi-def (I'm guessing progressive) and he was gonna give it to me after he finished using it! But he was dating a girl, she let a friend of theirs borrow it, and then the two of them split up and he never seen her or the projector again. I guess it was around 1,000$, if not more. Real nice one.

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

:-) you got the wrong model mits.... you need a laservue one.

Anyway, it is not a "simple" light source swap... the light engine does not have a color wheel because the "bulb" was replaced by three color leds that flash like a "fake" light wheel. Its disappointing that both mits and samsung abandon the design. People wanted "flat thin" that could be hung on a wall for "sexy". Ultra short throw projectors (front) are still alive and DLP continue to be one of the main stays even with 4k. They are just starting to roll out "affordable" laser / led based units (low powered / light output leds have been out for a bit).

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

good deal. Personally I like the dlp picture (mine is a samsung led based optical engine). The picture is good, glare from the room is reduced (screen finish is not gloss) and there is no worries about burn in.

happy viewing.

So that uses LED for a light source? Is it possible to somehow modify another make / model, such as this Mitsubishi, to use the LED optical engine? If so, I'd like to do that very much so. This mercury lamp is putting out soooo much heat, it worries me.

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

good deal. Personally I like the dlp picture (mine is a samsung led based optical engine). The picture is good, glare from the room is reduced (screen finish is not gloss) and there is no worries about burn in.

happy viewing.

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

There was definitely a short between the wires, the way they were twisted. Man, that was a hard fix. I mean, the fix itself was easy. Unsoldered the three wires, cleaned the board, chopped off the bad parts, soldered new black, yellow, and red wires on, used heat shrink tubing to insulate them, twisted them the best I could, then soldered the new wires back to the board.

Worked like a charm and the TV appears to be working properly now.

The lamp energy level is set to Bright. Contrast is all the way up to 63 (the way it was when I received it). It doesn't appear as bright as I would have thought it'd be, but it's brighter, not dim like it was. I think it might be just different than what I'm used to. The picture quality is nice, but richer, maybe more than my plasma. So I think perhaps it's just something I'm not used to.

Lamp itself is burning nice and bright. Putting off a good amount of heat as well. I think this TV is officially done now. No more burning smell of plastic either. Originally, I thought that was just from the dust, but it didn't smell right, smelt like burning plastic. I bet that's exactly what it was. Smelt it the first time I turned it on, before I opened it up and saw all the dirt, but didn't see anything burnt back then.

Thanks for all the help guys!!!!!!!!!

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

it is likely the. wiring. provides a "pulse stream" back to the controller.... hence if they are missing or otherwise then the system may error. the twist may be important in terms of. signal interference... maybe. you might try some liquid insulation on the bare parts first along. with checking for shorts between wires with a meter to verify a problem.

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

As indicated above... if the color wheel causes an issue (ie. such as the system is unable to detect proper spin speed), then in most cases, this type of error "usually" occurs at startup, and the lamp would normally not be "striken" (started). However, if the error occurs during "normal run" then its possible that the unit would then shut down the lamp to prevent damage to a slow wheel or otherwise. You can check this with a "viewing" test" such that when the image disappears, look "carefully" at the light engine to see if the lamp is still lit. Of course, if you can eventually get a display again, you could also check the "counters / errors" to see if there was a "0061" happening again.

Further, in DLP land, brightness of an image is usually achieved in two ways: one from the actual bulb rating and two from the color wheel itself. On some designs, a "blank" / white segment is used for both sync AND improved brightness levels. I am not sure about the Mits design but other projector manufacturers (eg. optoma) use this mode. On your wheel, what is the colors segments specifically going around the wheel?

Further: Looking at a bit of stuff around this, it would appear that perhaps, then sensor is able to determine intensity of light in terms of range such that the main control can decide on how long to "turn on" the dlp chip segments to brighten or reduce intensity. It maybe possible that the sensor is coated with gunk such that this "work" is wrong... or there is a wiring issue. There might be some checks for this or perhaps some cleaning (carefully) of the sensor. What maybe happening is that the sensor is not detecting sufficient brightness as "requested" by the controller, so the controller is upping the "dlp activity" level to get more brightness. However, the system feedback via the sensor still does not show the expected "improvement" (or runs out of "on off" cycles for the dlp) and thus eventually the system "errors" and shuts down.

I think the Red and Yellow wires being shorted out is what's throwing the 0061. It might be hard to tell from the pics, but the yellow, red, and black are all twisted together, and the yellow and red have the insulation melted off about equal distances, both shorting out. The way it was wrapped, it wasn't like a full short, it was like eh, they could be touching, they might not be touching. I think this made it intermittent.

The colours on this wheel are (in this order):
Blue
Red
Green
Blue
Red
Green

So there's two of each colours, and they're 180 degrees apart from each other. So you have the Blue, and directly on the other side of the wheel is another blue.

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

In almost all dlp sets, if the color wheel has an issue, the lamp will not light at all, this to prevent the lamp from burning the color wheel disc. The lamp does not have a soft start, it is just the way these (UHP) type of lamps operate, they get slightly brighter after a few minutes of operation. It is a mercury discharge lamp, and it acts like a mercury vapor street lamp.
If there was a problem with the color wheel indexing, the color would be way off, If the colors are correct the indexing is correct.
I have seen some intermitint solder connections on the plugs on the dmd board in the past.

Yeah, I don't understand how the colours could possible have looked right. That's why I was ruling out the colour wheel, because I did various tests, such as looking at the TV from an angle, and it was fine. Two of these wires, the Y and R ones, are shorting out. I can't see how the picture could have displayed properly at all. I understand why this would have caused the input source to cycle, but I cannot for the life of me understand how the picture was being displayed properly with the short....

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

there is nothing special about the wires other than perhaps they need to have some thermal value to prevent the insulation from melting. You can likely just splice / replace the run of wire or provide some insulation to ensure no shorts. Get your meter and check end to end continuity of each wire... that may tell you if the existing wire has an issue or not.

I'm going to do that. I'd love to replace the wires, rather than splicing into them, but I cannot identify the connector on the end, nor can I find my caliper, which would greatly help.

Unfortunetly, I think cutting out the bad, putting new wire in is the way I gotta go with this. I've been reading, and some people with similar DLPs (not the exact same model, but close) say there's a heating issue where the colour wheel is, and it damages the wires and the photointerrupter. They replace the photointerrupter and try various things, like adding a fan to try and cool the area. I'd rather not do that, but I'm trying to think what could have caused this damage. If it's getting so hot, it's actually melting the insulation off the wires in there, then perhaps external cooling is the way to go.

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

As indicated above... if the color wheel causes an issue (ie. such as the system is unable to detect proper spin speed), then in most cases, this type of error "usually" occurs at startup, and the lamp would normally not be "striken" (started). However, if the error occurs during "normal run" then its possible that the unit would then shut down the lamp to prevent damage to a slow wheel or otherwise. You can check this with a "viewing" test" such that when the image disappears, look "carefully" at the light engine to see if the lamp is still lit. Of course, if you can eventually get a display again, you could also check the "counters / errors" to see if there was a "0061" happening again.

Further, in DLP land, brightness of an image is usually achieved in two ways: one from the actual bulb rating and two from the color wheel itself. On some designs, a "blank" / white segment is used for both sync AND improved brightness levels. I am not sure about the Mits design but other projector manufacturers (eg. optoma) use this mode. On your wheel, what is the colors segments specifically going around the wheel?

Further: Looking at a bit of stuff around this, it would appear that perhaps, then sensor is able to determine intensity of light in terms of range such that the main control can decide on how long to "turn on" the dlp chip segments to brighten or reduce intensity. It maybe possible that the sensor is coated with gunk such that this "work" is wrong... or there is a wiring issue. There might be some checks for this or perhaps some cleaning (carefully) of the sensor. What maybe happening is that the sensor is not detecting sufficient brightness as "requested" by the controller, so the controller is upping the "dlp activity" level to get more brightness. However, the system feedback via the sensor still does not show the expected "improvement" (or runs out of "on off" cycles for the dlp) and thus eventually the system "errors" and shuts down.

[R_J]

Re: Dim Mitsubishi WD-73738 DLP Telivision

In almost all dlp sets, if the color wheel has an issue, the lamp will not light at all, this to prevent the lamp from burning the color wheel disc. The lamp does not have a soft start, it is just the way these (UHP) type of lamps operate, they get slightly brighter after a few minutes of operation. It is a mercury discharge lamp, and it acts like a mercury vapor street lamp.
If there was a problem with the color wheel indexing, the color would be way off, If the colors are correct the indexing is correct.
I have seen some intermitint solder connections on the plugs on the dmd board in the past.

[budwich]

Re: Dim Mitsubishi WD-73738 DLP Telivision

there is nothing special about the wires other than perhaps they need to have some thermal value to prevent the insulation from melting. You can likely just splice / replace the run of wire or provide some insulation to ensure no shorts. Get your meter and check end to end continuity of each wire... that may tell you if the existing wire has an issue or not.

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

What do you guys think? Having hard time finding a replacement PCB. Was thinking the photointerrupter is probably good, because we get a picture sometimes. Figured maybe those two wires, Y and R, being shorted out is causing the issue, and if I could not find a replacement board, perhaps I could somehow replace the wires. The connector that plugs into the DMD board (the one that comes off this photo sensor PCB) isn't really a common one. I have a bunch of different connectors that I save, just in case I need to replace one, but this has a little lock you gotta push down on to remove it. I don't have any like that.

What do you guys think? Try to replace the entire board or attempt a repair?

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

Holy cow! I think I _FINALLY_!!!!! figured out the problem! I was looking at colour wheels on eBay for this TV, trying to find a part, because internet says for Mitsubishi 2011 model DLPs, 0061 is Lamp Enable Not Issued and the reason is Possible bad Colour Wheel.

I seen on ebay they got this tape or glue or something on the middle metal spinning disc (that the colours attach to). I thought maybe that had come off. Some wheels on eBay said if the black tape wasn't at the right colour as the original wheel, to move it to the proper colour. I thought maybe this "marker" came off so I removed the colour wheel again to check. It was still in place.

So, I removed the sensor board, and low and behold, the wires are burnt, one missing it's insulation all together for like half an inch. Board itself looks bad and I will post pics after dinner.

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

I believe most DLP TVs start slightly dimmer and get gradually brighter. The process is only a few minutes. This may be a mechanism to prolong lamp life, which makes a lot of sense.

Similar to a soft-start motor so you don't ramp up the speed and hence the electrical current in the motor which causes it to get hot or risk burn out.

In a DLP lamp, you may soft-start the lamp to get it lit, then gradually increase the current to achieve required brightness but you don't ramp up the current immediately or you risk burning out the lamp prematurely.

That makes sense. A warm-up period.

[Spork Schivago]

Re: Dim Mitsubishi WD-73738 DLP Telivision

If the video becomes good at some point, then It's not a dust issue in the light engine, likely something in the video circuit, try using another input, something other than hdmi.
It could be bad smd elctrolytics on the video board.
When the picture is bright or when it is darker, how does the menu look, is it also brighter/darker.

I believe the menu is also darker, but I will have to verify. Right now, I couldn't get the video to stop cycling, regardless of what HDMI input I had it on, however, I wasn't able to test the other input types, such as RCA. However, I believe the HDMI ports weren't causing this problem, because the OSD (menu) would cycle with it. I hit the menu button on the remote control, not the physical TV. I think once this problem is fixed, perhaps the brightness will be fixed. But where to start with this problem? I don't know enough about DLPs.