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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
Hi all, I found the two broken (won't power on) projectors. I was hoping to turn at least one of the DLPs into some sort of display even if all it does is projects random moving dots onto a wall..
How feasible is this? I understand that they need both positive and negative supplies and function somewhat like a shift register where you clock data into the underlying CMOS array then "flash" the pixels with +V to display an image then reset using -v for the next one.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
DLPs usually fail due to a lamp ($$$), lamp ballast, or color wheel (old tech). There are people who have tricked devices into powering on without an OEM lamp by tapping the ballast control lines. Then adding a high powered LED block into the void created in front of the beam splitter.
Modern Liquid-crystal-on-CMOS based projectors usually use 3 switched color LEDs or Lasers to drive the output image stage. These require a special driver chip to interface a proprietary TI bus, as data rates are mostly FPGA only. There is little documentation on the specifics available to the public except the kits.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
Thanks! I did wonder about using an old hackers trick of "injecting" 24VAC from a replacement winding wrapped through the SMPS transformer, connected to a lighting module. This should at least give me an idea of which line goes where and the projector could power up somewhat.
Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 373
I've actually circuit-bent a DLP projector for my maskless lithography project. After buying several projectors I feel like the ones with a separate HID ballast work best because there are only two to three optocouplers going to the driver board. (Forward: HID on / eco mode, feedback: HID power good).
DLPs create grayscale values by temporal dithering (see youtube kZobrwFgWg0) so a high bandwidth, wide interface must be used. Not sure to what extent row/column multiplexing is used but I imagine one would fry the logic level inputs of the on-chip demuxers/drivers before any mirror moves in its own. Even chips that come with flex cables have a massively wide interface.
It would be best to get the electronics working again, then you can have a lot of fun with the DLP engine.
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Recycling DLP chips
