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744 LCD Display Units

Old 10th Aug 2019, 13:55
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744 LCD Display Units

Are there any service or repair documents available for these DU-7001 LCD units? I have one here that overheats and shuts down in the Sim after about 10 minutes. Probably too expensive to have it repaired by the manufacturer.
Any tips would be most welcomed.
Thanks.
Rob
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Old 12th Aug 2019, 12:00
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blue up,

What is the unit?

McHale.
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Old 12th Aug 2019, 14:09
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Insufficient cooling.
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Old 13th Aug 2019, 08:24
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It's a Collins DU-7001, Mod state 5, part numbers 822-1714-100 and 16XYKG, MFR 4V792.

Any suggestions would be handy.

Thanks
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Old 13th Aug 2019, 23:30
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blue up,

I agree with spannersatcx, insufficient cooling, pull the unit out and check for dust/debris accumulation around the units cooling holes, clean and reinstall and go from there. Hope it helps.

McHale.
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Old 14th Aug 2019, 05:29
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Thanks, guys.

Tried that on day one without any change. We used to have lots of cooling problems here with the antiquated equipment but I managed to fix the coolers and drop the cockpit temp from 28c down to about 21c. Not the best design of heat exchanger.

Another strange thing I noticed is that these LCD screens look odd in the lower Eicas position because they seem to turn a faded grey colour when the light shines at an angle. Tempted to put a CRT screen back in that position. Can't complain too much since I got all the LCD screens for free.

Any suggestions for the recommended cleaning product for LCD screens?
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Old 14th Aug 2019, 21:02
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Visial wipes
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Old 14th Aug 2019, 22:00
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The grey is the backlight typical of lcd’s which might also give a lead as to why thermal cutoff is occurring if it’s the lower eicas that’s failing... Just an idea. I remember the lcd du’s on the real frame were weird looking because of the back lighting even compared to other types like 737.
the brightness may be symptomatic of a fault with something else like brightness control such as the remote light sensor or the brightness knob. Again, just another idea.

Also. Why not touch base with Rockwell (or whomever the manufacturer is) and seek a suggestion if it’s a home build and not commercial. Apologies if I’m telling you how to suck eggs

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Old 15th Aug 2019, 05:55
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The 'greyness' seems to be more of a feature of the plastic screen when compared to the glass of the older CRT ones. The plastic seems to have a texture to it that reflects some of the light from the overhead lighting. I'll try Rockwell Collins again when I get back off leave. I've had trouble with the seat motors but have had the most wonderful help from Ipeco, the manufacturer, who have sent manuals and wiring diagrams within minutes of me asking.

I'm hoping to get this screen back working since they seem to be somewhere over 55,000 each these days.


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Old 15th Aug 2019, 09:53
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Wow hey, that looks cool! I wonder if I’m tall enough to go on that ride?

are the pvd’s operational?

good luck. Sorry couldn’t be of more use
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Old 15th Aug 2019, 13:25
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Sadly, I'm only rated on the 747 and S61 Sims. If anyone wants to buy themselves an early Christmas present then I have some vacant sessions on the 747...
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Old 16th Aug 2019, 05:58
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Wink

Originally Posted by blue up View Post
Thanks, guys.

Tried that on day one without any change. We used to have lots of cooling problems here with the antiquated equipment but I managed to fix the coolers and drop the cockpit temp from 28c down to about 21c. Not the best design of heat exchanger.
As mentioned before it sounds like an cooling problem-i would look at your equipment cooling side of things not the cockpit environment cooling as these screens rely on fairly strong cooling airflow from the backside in the real world..
Our cockpits are frequently above 90f on ground/in hanger and we have no problems with these screens-
people on the other hand struggle.
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Old 20th Aug 2019, 12:22
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Would agree to on cooling should be the first thing to look at. Personally remember swapping CRTs around as a scheduled task on certain A Checks to reduce screen burn in.

Every time you pulled one out there would be a good flow of forced air coming out and sometimes a face full of dust.

Flow is probably more important than temperature of the forced air as its the flow that carries the heat away more that the temperature of the air.
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Old 21st Aug 2019, 00:48
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By the look of his arrangement, the sim is professionally built so unless there is something wrong with the specific duct for equipment cooling in the lower eicas spot, equipment cooling can be reasonably ruled out (but should be checked) based on other screens still operating normally.

as op and others have diagnosed, it is a fault with the DU itself probably arising from heating issues, just as in consumer electronics.

if there are any technicians with experience fixing du’s, why not drop a line.
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Old 21st Aug 2019, 09:16
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[color=left=#000000]By the look of his arrangement, the sim is professionally built[/color]
If it is the Cardiff 744 shown in the images, this is an EASA MCC/JOC/APS approved device which I believe was formerly Level D or similar.
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Old 23rd Aug 2019, 07:00
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Level CG at the moment.
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Old 23rd Aug 2019, 18:44
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No knowledge of the unit in question but at a generic level if the obvious cooling issues have been checked I would suspect that the issue could be related to the backlight for the LCD getting old.
Depending on vintage it likely is a fluorescent tube of some sort and these do age and have lower output/efficiency so they may be running hot.

The other thing to check is the internal power supplies, make sure they are within specifications and ripple free. Even without specs/schematics it is usually possible to guess at what voltage they should be, especially if you have a working unit to compare. I have seen cases where things continue to operate with a wildly out of spec power input including one case of the primary supply in a repeated shutdown cycle. The first symptom was things were 'warm' but still working.

When you say overheats and shuts down is there an over temp alarm preceding the shutdown or is it assumed that it shutdown due to overtemp?

Again no knowledge of these or similar aircraft units, mostly based on experience reviving old computer displays, which is a 'sport/challenge' pastime and not cost effective if hours are billed at > $10/hour. This may apply in your case as well...
BTW: If you do find a bad power supply nothing says you have to find a direct replacement, the monitor I am looking at at the moment has an external box replacing the failed internal 12v/5v supply. Obviously not flight worthy
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