I just picked up a used 5700 projector from a buddy of mine. I got a good deal, but that's mostly due to the dust blobs. I'm pretty excited about it nonetheless!

I've seen that others have had dust blob issues with their 5700 pj, but no answers as to how to self service it. I was inspired by the pictorial writeup of the 4805 dust blob cleaning, and attempted to take mine apart. I succeeded in removing the top and the focus and zoom rings, then I got stuck. For the 4805, you remove the screws holding the lens in place, pull out the lens, and then spray compressed air inside to clear the mirrors or something. I can't figure out how to get the lens out without removing the pc board, and I'm not sure I want to go there.

Please help!

I could not find a service manual for the 5700, so I bought the service manual for the 7205 which appears to have the same chassis, etc; ditto for 7200 and 7210. It explains how to remove the optical engine (which includes the lens, light tunnel, color wheel, DMD chamber, and DMD driver board), but says nothing of actually taking the optical engine apart. It is considered a replaceable item from a servicing point of view. Has anyone taken one of these apart? I'm afraid of introducing more dust particles by trying to clean it. According to my friend from whom I bought the unit, the dust blobs have been present from day one. For whatever reason, he never sent it back to Infocus under warranty, and now the warranty is up.

I've been inside a 5700, but it's been a long time. On any DLP projector, any dust that is visible in the image is going to be either on the imaging chip itself or an optic that is in the chamber with it. Look to see if there is a metal cover plate with screws in the area directly behind the lens. That is the chamber. Open that up and canned air to blast away the dust, being very careful not to allow the spray to come out as a liquid. If you still have difficulties, post an image of the assembly. As I said, I have not been inside that model in some time and I can't recall the important details.

I have a 5700 (it's now a back-up to a 7210) that had what looked like some kind of hair suddenly appear in the image. It was on the intake side of the image so while the projector was turned off I applied a vacuum hose to the inlet grate and let it suck in for a minute or so.

When I turned the unit back on the image was once more pristine.

The 5700 when working well gave a very good image and held its own when compared to the 7210 (at least when not an a side-by-side basis).

The biggest weakness of the 5700 was that it had a slight high pitched color wheel whine in addition to the more soothing sound of the fan. Most people would not notice it but I did.

The 7210 has no color wheel whine and if anything the fan is quieter than on the 5700. However, while the 5700's fan ran at a constant speed the 7210 switches between a low and high setting. Occasionally I notice the fan sound when it switches up.

Anytime you hear the color wheel, expect it to fail. It may take some time, but it will fail.

Thank you Sheridan for your insight. I took the projector apart last night and removed the optical engine. There was a slight difference to the 7205 manual that I have, but it was straightforward. There is a bracket on top of the opt eng that I removed which gave me access to two of the three screws holding the lens (the third was easily accessible). Once I pulled the lens out, I could clearly see two "big" particles, and I gave it a shot of the canned air - no effect. The particles were on the other side of the chamber. I removed the four screws holding in the driver board. As I pulled that apart, I saw that there was a white foam gasket sealing the area, and that the gasket was shedding bits, and two large bits were directly on the mirror surface pressed against the glass. I cleared that away with the canned air, gave a good spray to the gasket, crossed my fingers, and put everything back together. And it worked! The image is no longer hampered by those blobs. In all it took me about an hour.

Any insight on doing it with an IN76? Other than the blobs, it is great. I don't want to shell out $1k+ to equal it.

Thanks.

The procedure should be the same. Remove the top cover, locate the imaging chamber directly behind the lens. It should have a cover that can be removed, blast the inside with canned air (NO VAPOR), reassemble and use.

Now, I have never been inside an IN76, but it is still an Infocus projector. So the architecture should be similar. For that matter, the architecture should be similar for ANY DLP projector. They're ALL based on the same imaging chip and optics design.

In most cases, it will not be necessary to remove the optical engine to do this.

Any insight on doing it with an IN76? Other than the blobs, it is great. I don't want to shell out $1k+ to equal it.

Thanks.
Hi Heboil,

I cleaned some blobs out of my IN76 recently and posted these instructions:
http://www.avsforum.com/avs-vb/showpost.php?p=15764906&postcount=1

There are some pictures, but I didn't think to take any until I had already started reassembling the projector so they don't show everything.

It was pretty easy. If any of the instructions are confusing, let me know and I'll try to clarify. You want to remove the lens and get to the inside of the optical chamber that way. On the IN76 that's going to be easier than trying to remove any cover on the optical chamber IMO.

Jeff

Thanks for posting those pictures. I can see that my advice was a little off. While the optical pathway is still similar, the IN76 has extra "stuph" on top of the chamber that makes my method impractical. Good post.

Thx Sheridan1952. The IN76 is such a neglected animal on this forum, that I thought I was wasting my time when I posted the instructions. Glad to see at least 1 other member may get some use of it. :)

JeffKB -

Thanks a million!!! My projector died too... and when it came back... voila! Dust blobs. I am a little upset it is Monday night... I probably won't have the time to do this until the weekend... but I will spend much time thinking about it over the next few days. If I run into any problems, I will definitely PM you. If I can get this fixed, a new bulb and I will feel like it is a brand new day! I still love the picture it produces. I will definitely post back and let you know how it turns out.

JeffKB -

Thanks a million!!! My projector died too... and when it came back... voila! Dust blobs. I am a little upset it is Monday night... I probably won't have the time to do this until the weekend... but I will spend much time thinking about it over the next few days. If I run into any problems, I will definitely PM you. If I can get this fixed, a new bulb and I will feel like it is a brand new day! I still love the picture it produces. I will definitely post back and let you know how it turns out.

Heboil - no problem, glad to see my post could be of some use to someone. :D Don't worry, it's really not that hard - just take your time. By the end of the weekend you'll be dustblob free. Feel free to PM anytime. :)