Fixing defective DLP DMD chip?

[John Robertson]

I've ordered a replacement display chip for our 2013 Benq MW519
projector and I see that the youtube folks say this Digital Mirror
Display can't be serviced.

So, being the contrary kind of person I am, I figure - well maybe it can?

Thus the question - has anyone here played with one of these and if so,
any success what so ever? Our display has (so far) 3 bad mirrors roughly
near the middle of the screen so somewhat annoying. I figure when I have
the replacement (eBay, used, there don't seem to be any new available)
in hand then I might be willing to experiment on the sick unit. Unlikely
that I can save it, but who knows?

Time will come to break out the binocular microscope and see what is
going on...

John :-#)#

[John-Del]

I've changed a couple of hundred in Mitsubishi and Samsung rear projectors, and the DMD chips were Texas Instruments.

https://cdn.shopify.com/s/files/1/0189/1890/files/4719-001997_1910-6143W_DLP_Chip_ee98eb65-0def-4d08-94d1-a7bb58da1051.jpg?v=1524157252

From what the engineers told me, the mirror pivots fracture over time leaving some mirrors stuck open and some stuck closed (light and dark spots).

I had previously tried heating, cooling, and g-shocking the chips, but there was never any change.

I would never use a used DMD unless the customer is informed the replacement may very well start spitting out stars in mere months.

[John Robertson]

I am the end-user of the used DMD, I don't have a part number for the
original and so ended up buying a used one. I agree it won't be as
reliable as new, but without the part number I was hooped. And we are
losing one pixel a day now.

Are these still available as new or NOS?

Thanks,

John :-#)#

[John-Del]

The ones for the Mitsu and Samsung (same part number) were as recently as 3 months ago when I got one from Mitsu, but supposedly TI is either eliminating production or already has. Does the one you need look like the one in the link I posted?

[John Robertson]

I have not pulled out my original. I am waiting for the replacement
before shutting down our home projector... According to the photo on
eBay (yeah...!) it does not look like that. This was what I ordered:

https://www.ebay.com/itm/223202086282

Thanks for taking the time to respond!

John :-#)#

[John Robertson]

On 2019/09/09 6:37 a.m., John-Del wrote:

TI at least still lists it. I should have thought of searching on TI's
site before as I think this is the DMD I am looking for:

http://www.ti.com/dlp-chip/display-and-projection/standard-chipsets/products.html?pqs=paqs&familyid=3554#p2841max=WXGA%20(1280x800)&p1907=DMD&p1913=1280x800

or in tinyURL speak:

https://tinyurl.com/TI-DMD

John :-#)#

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[John Robertson]

On 2019/09/09 6:37 a.m., John-Del wrote:

Mouser has 47 of these DLP650LEFYL DMD chips left in stock @ $153USD.
Damn. Should have bought from them!

John :-#(#

[John-Del]

One of my buddies had a contract with a city near us to maintain their projectors, and they changed TONs of those. If you're planning to keep the projector for a few more years, I suggest buying one of the remaining new DMD chips.

[John Robertson]

Hi John,

What do you recommend for the heatsink compound/film for the DMD chip?

Also the face of this new chip (from Mouser) appears to be dusty, they
simply packed the chip without any plastic wrapping in an antistat.com
foam box. Is there any way to clean it or do I take this up with Mouser?

Thanks!

[John Robertson]

Looking closer I see that there is a clear window, I assume I can clean
that using similar practices used on camera lens...

So, just what does it need for the heatsink junction is my question. I
don't trust youtubers that much.

[John-Del]

The DMD chips supplied by Mitsu and Samsung included the same thin thermal pad they were originally equipped with.

The few that I swapped from donors I used Dow 340 (my favorite heat sink compound). You certainly can use Arctic Silver or other similar compound. I don't think that chip gets particularly hot in any case.

The front window is uncoated glass, and you can use anything on it to clean it.

I'm concerned with the dust though.. Mouser has always been a good supplier but I wonder if the DMD chip you got isn't a used one. Before installing it, look at it under a strong eye loop while slowly rotating it. Any stuck pixels will stand out.

[John Robertson]

The dust blew off...and no stuck pixels.

The replacement TI chip worked just fine, and I used thermal paste
instead of a thermal pad. I did check that the chip was under some
compression against the heat sink prior to using the compound, and we
polished the contact face of the heatsink hoping to get a slightly
better heat transfer. I assume (hope) that was a good idea...

Ran it last night for five hours...

Thanks for the advice!

John :-#)#

[Jeff Urban]

>I did check that the chip was under some
>compression against the heat sink prior to using the compound, >and we polished the contact face of the heatsink hoping to get a >slightly better heat transfer. I assume (hope) that was a good >idea..

Another thing about heatsink compound, otherwise known as birdshit is you do not spread it. You put it at the center of the pressure and squeeze it, this does not make air pockets. Air pockets defeat the whole purpose, enough of them you might as well put it on dry, or maybe lick it.

When I fix the high power shit it stays fixed.

[John Robertson]

Thanks for the note, yes, that was what I did, just a large drop in the
middle then compress evenly.

John :-#)#