Dmd chip difference

Frankmich

Novice Member
Hello. Does anyone know the difference between dmd chip 1272-6038 and 1280-6338

Is the 1280 a newer chip or is it the resulution I can't find any dokuments on the web that explain the difference.
I have pixel fails on my optoma and I whant to buy the right chip please help
 

Sandra51

Active Member
You have already posted in this thread :

Optoma HD600X DMD chip replacement | AVForums

So if you read back through it you will see that no one has found what the numbers really mean so far, but that the 1280 ones appear to work perfectly fine in place of the 1272 ones and, as the 1272 ones appear to be non existent, that the 1280s are the newer and hopefully improved replacements. I don't think that they change the resolution from 720p to 1080p though.
 

Sandra51

Active Member
Its a shame that 5 or more of us all didn't need one at the same time.
They would have been quite a bit cheaper for each one, if we could have all got together and placed a single order for 5 or more.
 

Frankmich

Novice Member
I did place a order for a 1280 chip. The seller told me that I might se a shadow at the bottom off the picture because the 1280 has a resolution of 1280/800 ??
 

Sandra51

Active Member
I cant say that I have seen any difference between the 1280 and the 1272 on mine.
Maybe on of the others that have replaced from that other thread will see this thread and reply if they saw anything.
 

Frankmich

Novice Member
I Got it for 130$ including dhl to Denmark. From alibaba. And a fre cooling paste but I will buy the artiv silver 5
 

Sandra51

Active Member
I will be interested in seeing if you notice any difference. Good luck fitting it, as others have mentioned just be careful of catching the colour wheel when installing it as its easily damaged from what others have said.

I wonder if the 1272 is a code for 1280 x 720 and the 1280 is code for 1280 x 800, which would make it the same as WXGA which has more pixels or in the case of DMD chips, mirrors. If the pins are the same you would think it would control the same percentage of mirrors though as there isn't a separate pin for each mirror/pixel.
Maybe someone who understands how these things work could explain what, if any difference we should be looking for or expecting.
 

Sandra51

Active Member
I wish someone would confirm if our suspicions are correct or not.
It seems strange that there isn't any information on the internet about these DMD chips.
 

Sandra51

Active Member
Really fed up this evening.
I watched the MotoGP from around 5pm until 7.30pm and everything was fine then I left the projector on while I made my evening meal and started watching a film shortly after 8pm. I noticed some black dots in the bottom 12 inches or so of the screen, along the full width. I checked that there wasn't any dust on the lens and changed to a live broadcast instead of the recorded film in case it was something on the film. The marks were still there. By 9pm a couple of white dots had appeared, quickly followed by several more. By the time I had finished watching the film there were too many white dots to count, much more than there were on the original DMD chip. I checked the total hours since I replaced the chip and its just done 27 hours since I replaced it on April 1st but apart from an initial brief test to check that all was OK it was the following weekend before it was fastened to the ceiling again and used for a few hours.

I have contacted the supplier to see what they are going to do about it as the invoice did say that it was guaranteed for 30 days from delivery, so I may or may not be covered and to what extent I am uncertain.
Has anyone else had any problems after replacing their DMD chip after such a short time ?
 

Sandra51

Active Member
I am gutted too.
I haven't heard anyone else say that their replacement failed. I cant think it was anything that I did as I have built, repaired and upgraded lots of PCs, including laptops and have never had anything fail so soon after replacing a cpu, which the DMD chip is as close as you can get to that type of thing. I cleaned the surface of the heatsink with isopropanol and used more arctic silver thermal paste than I would have done on a cpu as the surface of the heatsink wasn't as smooth as PCs usually are.
I didn't try and improve the surface of the heatsink as the screws that hold it in contact with the DMD chip are shouldered and I wasn't sure how much I could safely remove if I tried to make it smoother so I opted for using a lot of the thermal paste to do the job.
If it was my fault I would have expected it to have failed after a couple of hours at most not after 20 plus hours. The strange thing is as well that it started showing the black dots as almost horizontal dotted lines in the bottom few inches of the screen initially which increased in number but still mainly in lines up to about 12 inches or so before the white dots started to appear. The white dots were completely randomised and even when there were too many to count, the black dots and white dots were all concentrated in the lower third of the screen area.
I don't know if that means anything to anyone as to whether its a faulty chip or my assembly method ?

The Chinese firm hasn't replied yet, which looks rather ominous :(
 

Frankmich

Novice Member
Just received the dmd chip from dhl. They picked it up in Hong Kong the 29st march and I got it today the 1st of May. That's fast. And they had excellent track and trace. I will mount it later today
 

Sandra51

Active Member
Good luck with it.

My supplier is trying to get out of the warranty by saying its after 30 days from them getting it picked up from their warehouse by DHL. It was collected from them at 15.32 on March 29th and I received it at 13.10 on March 31st and it went faulty in the evening of April 27th. I tried to contact them in the early hours of the 28th, so I think they are working on the dates March 29th and April 28th, which is being silly, especially as there is large time difference between the UK and Hong Kong which compresses the time between leaving the factory and arriving here by around 10 hours and extend it the other way by a similar amount.
 

Sandra51

Active Member
I am still waiting for a reply :(
I paid via PayPal so hopefully if they continue to ignore me I will raise a dispute with alibaba.com and with PayPal.
 

Frankmich

Novice Member
Now I got it installed. And it works great.
As you can se the top dmd has a bigger mirror. That's the 1280-
The bottom one is 1272





There is a little shaddow in the bottom of the screen. But it's nothing to the picture. I'm happy



Also a small one in the top


So it must be that, 1272 means 1280-720p
And 1280 means 1280-800p
 

Sandra51

Active Member
Pleased its worked out OK. I didn't notice on mine if it had those shadows or not or not as my screen isn't fully masked to 16:9, 4:3 and the other resolutions that the stuff I watch comes in, so even with the original chip I sometimes had that effect.

Still no reply from my supplier so it looks like will have t be taking it up with Alibaba.com
 

SteveCritten

Distinguished Member
Sandra I was under the impression that putting too much paste is as bad as not enough? In the case of CPUs anyway as the thicker paste prevents the heat sink working to its optimum by drawing the heat away from the chip. Now I am no expert just what I read when building my sons PC.
 

Sandra51

Active Member
You are right about that Steve and if it had been as good a finish as on a PCs CPU heat sink it would be a case of less is more, as they say.
The surface of the heat sink on the projector was, in comparison, quite rough so I had to put more on than I would do with a PCs CPU to be certain that it would fill the gaps. The hold down screws are shouldered and have springs on them so I daren't try and smooth the surface as the screws may not then have pulled it down firmly enough to get a good contact.
The paste that was originally on didn't fully cover the surface of the heat sink and wasn't as thick as the thermal pads I have seen that comes with some heat sink/fan assemblies for PCs but was thick enough to be able to peel off with my fingernail.
 

Frankmich

Novice Member
Never the less. I wouldn't recommend this 1280- chip to people who has a fixed screen on the wall Or masking on the projector screen. That are currently using the original 1272 chip
 

RandomBoy

Novice Member
Hi there, I know it's very a very old post. But what was the final feedback about this story?
How long did your chip last?
Did the seller refund Sandra?
 

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