Film-Tech Forum ARCHIVE: DA-20 won't light motor LED's in front

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Posted by Michael Trudell (Member # 3344) on 07-25-2007, 02:35 AM:

Greetings,

Has anyone had a situation with a DA-20 that won't operate the Motor 1 or 2 LEDs? I have the standard factory installed jumper on the motor start DB9 terminal, but it won't display the result on the front of the panel. Of course, it makes reversion to SR impossible.

This is for a private screening room, and I am not running any automation. It is plugged into a CP65. FWIW, my DTS falls back to SR nicely and I've even removed the DTS breakout board and plugging the automation cable directly to the CP65. I have already contacted Dolby today to get some help, and they're stumped as well. Just hoping that someone out there may have had a similar experience.

I'm hoping it's not a Cat 611A card.

Mike

Posted by Steve Guttag (Member # 268) on 07-25-2007, 06:24 AM:

I've had those jumpers not soldered well (or even at all on a couple). Make sure the solder connections are good (re-wet them yourself).

Posted by Michael Trudell (Member # 3344) on 07-25-2007, 10:07 PM:

Thanks Steve for your reply,

I did pull the jumper and there is continuity between pins 1 and 5. I even placed pins in the panel and connected them with a test lead with no results.

I did check that the Cat 611A board is okay with a known good DA20, and it senses the motor command just fine. The good news is that it is probably not the card, but the bad news is that I haven't found the problem.

Mike

Posted by Tristan Lane (Member # 1169) on 07-25-2007, 11:03 PM:

Bad solder joint on the edge connector for the 611A or the d-sub connector attached to the backplane?

Posted by Steve Guttag (Member # 268) on 07-26-2007, 06:37 PM:

My suggestion if you are authorized and are feeling up to it. Remove the screws that hold the connector half of the rear panel on (something like 4 on the top, 4 on the bottom). You will need to remove all of the things plugged into those connectors first.

When you pull that panel off you will see a mess of ribbon cables. Trace the one that deals with the motor start and RS232. They should plug into connector "P3" on the mother board. I suspect either it has pulled out/oxidized or there is a problem with the ribbon cable/connectors because that is about all that is left if you have verified that the Cat 611A is good on the motor start. Just for grins...have you checked to see if motor 2 lights? In a pinch, you can plug the video cable into Reader 2, connect motor 2 up and all will be fine. You should also connect up the control line for projector 2 but you will find that if JUST motor 2 is running that it automatically switches the changeover to P2 as well.

If you need to probe further. The Motor 1 control line comes into the Cat 611A (socket J19) on pin A16.

There IS a snubber network also on that line at it is possible that it has either bad soldering or has opened. It should be labeled FL32. I believe it resides on the Card side of the mother board though but its solder pins should also be on the side that faces rear.

Steve

Posted by Michael Trudell (Member # 3344) on 07-29-2007, 07:53 PM:

Thanks Steve,

It's fixed.

I pulled the backplane out and the digital ground that runs both the motor start and serial data (J9 and J3) looks like it was burned at one time at the jumper path on the board between the two DB9s. The connection between the two digital grounds was open as a result, so neither motor start would connect to digital ground and turn on the light.

Per Dolby, I checked that the filter cap/snubber FL32 was okay before I did anything. Afterwards I made a jumper to connect the two pin 5s together again. That did the trick.

Don't know how long it's been there and/or what caused it at first, maybe a loose washer or screw fell in there at one time.

Mike

Posted by Steve Guttag (Member # 268) on 07-30-2007, 08:05 AM:

My guess is that voltage was presented to that pin (5) and the trace was the weak link and blew like a fuse. If hardware caused it, it would still be there. Something cause that trace to run more current than it is rated for.

Glad to hear it is fixed though.

Steve

Posted by Louis Bornwasser (Member # 3063) on 07-30-2007, 06:55 PM:

You cannot imagine the number of times I have seen CP-200/500/DA20,flamed by "beginners" who connect the 120 volt wire feeding the changeover directly to "changeover" terminals on these processors. WOW! Louis

Posted by Brad Miller (Member # 2) on 07-30-2007, 07:11 PM:

Ok Mike I retract my previous comment to you off-site. Apparently there ARE people stupid enough to do that!

Posted by Michael Trudell (Member # 3344) on 07-30-2007, 07:40 PM:

LOL!! [Big Grin]

That made my day! [thumbsup]