I purchased my Laservue L75-A91 on 5/31/2010. In April 2013 it displayed 2 white dots which by May 2013 had increased into about 100 white & 200 black dots. I found out that this is an end of life wear out of the DMD chip where the digital micromirrors get stuck. This is a bummer paying $5K for the TV that lasts less than 3 years and finding out that Mitsubishi no longer sells the replacement light engine, nor are their authorized service centers willing to do out of warranty work on the TV set even though I'm willing to pay them to replace the Texas Instrument part number 1910-6143W chip (Mitsubishi part number 276P595010). I was not willing to take Mitsubishi's $1000 buy back offer if I could fix it myself for less than $200.00 using only 4 screw drivers (a Star Head/TORX® T20, a # 2 Philips, a # 1 Philips and a # 2 flat blade).
I found the 52 page L75-A91 ( Version 9.0 dated 11/12/2010 ) service manual online at:
It cost me a little over $5 to download as a 17.9Mb Adobe pdf file.
All other Laservue Model service manuals are there too.
I purchased the replacement chip which arrived June 13, 2013. Prices for the chip range from $135 purchased directly from China to $190 from ShopJimmy.com.
The Service Manual only recommends removing as Field Replaceable Units the (1) Electrical Chassis Assembly, then (2) the Laser Light Source, and finally (3) the Optical Light Engine. The following 3 part numbers are what you'd search for on the internet.
(1) ASSY-CHASSIS 955B394002
(2) ASSY-LIGHT-SOURCE 870B009001
(3) ASSY-ENGINE 870B010001 (This is the assembly where I'll be replacing the defective chip.)
Clean up and remove as much dust as possible before you start the job, pay particular attention to the laser light source heat sink and fan assemblies that will likely have a lot of dust accumulation. Clean up all the dust you can. Wear clean, white cotton gloves and a grounding strap (both available at just about any electronic store) when you do this job. Static discharges that you can't feel can kill or injure sensitive electronic parts so grounding yourself is essential. Use anti static bags to lay the DMD board & chip on when you're working on them. Take care not to touch the micro mirror side of the chip or allow it to touch the table when you remove and reattach its heat sink. Treat exposed optics with care. Use an air brush designed for optical lens cleaning to remove dust. I've found that a brand new unused
Swiffer duster wiped gently across the optical surfaces (but not the chip) does a great job while not harming them. I cannot stress enough how important it is to clean all optical surfaces you see. Any dust in the optical path (especially on the DLP chip) will result in gray splochy areas on an otherwise black screen.
Rebuilding the Light Engine is best done in a Class 100 clean room or flow bench.The laser light source in this TV can permanently blind you
if you look directly at it or even have reflected laser light enter your eye. I was not worried about the laser though since the laser was not powered during the repair, and I assured I reinstall all protective shields the way they came off.
Because I've never repaired a TV before, it took me 4 hours to get to the defective DLP chip, and 2 hours to reassemble the TV.
My Laservue is back to its beautiful self again. I may buy a spare DLP chip to have on hand because this Laservue failure mode is well worth fixing.
Replacing the zero insertion force chip was easy after I got to the DMD board located on the bottom of the light engine, but to do that I had to:
1. Remove the 13 each Torx screws holding the rear cover on (8 on the back, 1 on the bottom left side, and 4 on the right side in the fan shroud) to remove the rear cover.
2. Remove the 6 each # 2 Philips screws securing the rear cabinet frame assembly (2 at the top, 2 at the bottom, and 2 to the chassis assembly) to remove the frame assembly.
3. I had to remove all of the connectors from the back of the chassis. Reassembly was easy because I labeled them with numbers as I removed them. I also had to remove three cables leading to the Laser Light assembly. Remove the cables by compressing the cable lock prior to pulling each connector out. Remove the 1 each Philips screw securing the electrical chassis assembly (it is located on the left side on the bottom of the electrical chassis) to remove the chassis. Slide the chassis up and out of the cabinet.
4. Remove the 8 each Philips screws securing the laser light source assembly. I only had to remove 3 cables from the Laser Light Source that ran between the Laser Light Source and the Chassis. You might do it differently. You can get 'stick-on numbers' to identify the cable and the adjoining plugs from Frys to help reassembly.
5. Remove the 3 each # 2 Philips screws securing the black plastic Service Cover to the top of the light engine assembly to remove the Service Cover.
6 Remove the 4 each # 2 Philips screws securing the light engine to the TV case. You'll have to remove all the wire and cables from this assembly. Mitsubishi doesn't recommend disassembling this assembly any further than to replace the DMD fan. But this is the assembly possessing the defective chip that is replaced in steps 7, 8 and 9.
7. Remove the 5 each # 1 Philips screws securing the ventilated cover with the DMD fan. Also remove the connector (blue arrow).
8. Before removing the DMD board from the bottom of the Light Engine you'll have to remove the 2 ribbon cables. The way you remove these cables is by unlocking them
from the connector. Gently compress the black ears located to the sides of the ribbon cable and simultaneously applying extraction pressure to the ears (NOT
the ribbon). When you feel the black ears rise, you're done. The ribbon cables are now unlocked and can be extracted. Do not touch the exposed ribbon cable conductors as your finger oils will cause a corrosion resulting in failure.
Remove the DMD board from the bottom of the Light Engine by first removing the 2 each Heat Sink screws securing the heat sink, and removing the 5 each # 1 Philips screws.
9. Rotate in a counterclockwise direction the flat blade black screw located to the side of the chip to unlock and remove the defective chip.
10. Insert the new chip and rotate the screw located to the side of the chip to lock and secure the chip by rotating the locking screw in a clockwise direction.
11. After cleaning off the old grey heat sink tape that Mitsubishi installed, apply a thin
coating of thermal compound to the heat sink contact area and reattach it.
I used some "Antec® Formula 7 Nano Diamond Thermal Compound" because it had the highest conductivity of 8.3W/mK. It cost about $15 at Fry's Electronics® but I'd estimate it is 2 to 3 times better at heat conduction than what the manufacturer used. I was taught in my Chemistry classes that every 10 degrees roughly doubles the rate of reaction. Since heat speeds the chip aging process, I figured using the best thermal compound would extend the chip's life.
12. Reinstall the DMD board with the 5 each # 1 Philips screws.
13. Reinstall the DMD boards ventilated cover with 5 each # 1 Philips screws; and reinstall the fan connector.
14. Reinstall the Light Engine with the 4 each # 2 Philips screws.
15. Reinstall the 3 each # 2 Philip screws securing the black plastic Service Cover to the top of the light engine assembly.
16. Reinstall the 8 each # 2 Philips screws securing the laser light source assembly.
17. Reinstall the 1 each # 2 Philips screw securing the electrical chassis assembly (it is located on the left side on the bottom of the electrical chassis).
18. Reinstall the 6 each # 2 Philips screws securing the rear cabinet frame assembly (2 at the top, 2 at the bottom, and 2 to the chassis assembly).
19. Reinstall all electrical connectors. Verify each is firmly seated again. Again, check to make sure all electrical connectors are reinstalled.
20. Reinstall the 13 Torx screws holding the rear cover on (8 on the back, 1 on the bottom left side, and 4 on the right side in the fan shroud).
21. Connect HDMI inputs back in, plug the TV back in to AC power and start it up.
Calibrate if necessary.