Film-Tech Forum ARCHIVE: CP-500 bad LCD

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Posted by Marin Zorica (Member # 1716) on 10-22-2010, 12:30 PM:

Does anybody knows why this LCD has horizontal lines, you can see on photo.

Should I need to change it or I could do some soldering inside?

Posted by Randy Stankey (Member # 64) on 10-22-2010, 12:41 PM:

Just a wild guess... Are all the ribbon connectors from the motherboard to the LCD tight and fully seated?

Posted by Tony Bandiera Jr (Member # 2365) on 10-22-2010, 01:59 PM:

Excellent advice Randy, that is the first thing to check. Also Martin, you could open the door and carefully wiggle the cables to see if the problem clears up.

Another thing to try is to power down the processor, then pull out the motherboard and re-seat it in the connectors. But be careful, as it tends to sag and it is possible to force it in without engaging the backplane connector.

If that doesn't work, one last thing to look at is if there is dust build-up in the back side of the door..carefully remove the back metal cover and using canned air (DO NOT use an air compressor as they ALL have moisture and oil in the air which is bad for the electronics) to blow out the dust.

If you have another CP-500 on hand, swap the doors and see if the problem stays with that door. (Door swap does NOT require any adjustment or recalibration of the processor.)

Finally, this could also be a sign of power supply trouble (Especially if you are having any other issues with that unit.)

If none of the above helps, time to get a replacement door.

Posted by Sam D. Chavez (Member # 1841) on 10-22-2010, 02:31 PM:

All good advice to be sure, but failing CP500 displays are very common.

Posted by Marin Zorica (Member # 1716) on 10-22-2010, 04:50 PM:

I think Sam is pretty close, need to find this LCD since dolby doesn't support them, and probably it worth fortune from them. But it's simple 240X128 LCD as I know based on some controller ic, so just need to find one with same controller.

Power supply, connectors, cables and so are okay, also unit is working great.

Posted by Brendan Penny (Member # 5041) on 10-25-2010, 10:05 PM:

I know 10 or so with the same problem. Figure its probably cheaper just to replace with a 750 or something eventually so haven't bothered to do anything about it!

Let us know if you find a cheap replacement though!

Posted by Tony Bandiera Jr (Member # 2365) on 10-25-2010, 10:25 PM:

I wonder how much Dolby would charge, if they had it...I seem to recall that even when the encoders went bad Dolby would only do a repair-exchange on the entire door.

I have a hunch that the display itself can be found at a place like Mouser or Digi-Key for example.

Posted by Marin Zorica (Member # 1716) on 10-26-2010, 03:43 AM:

Graphic display with 240X128 pixels is not hard to find, only problem is that this one uses SED1330 controller, and LCD with it is hard to find. I checked most of stores and so, but in 90% there is T6963 controller on other displays, which on first is simillar with one dolby uses, but I don't think it receives same instruction for display, so can't be used on dolby.

There is this web page and you can see AND1742MST2 LCD, on CP500 there is AND1742MST, I did send mail is it this MST2 compatabile with MST but still didn't get answer. Because there are some pins which are different between these two, but will wait for answer.