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TAF DMD problem - advice please

A

Annualman

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Scotland
My TAF has developed a display issue. Its the original display and board as far as I can tell. After a couple of hours - whether I am playing or it is just on - the display corrupts and then goes blank.

After a good few hours - or the next day - it works again for a while. I'm thinking it is overheating? Thus board probably faulty.

Should I replace board / get board repaired? If so should I get a new replacement one or a refurbed original? If the latter does anyone have one?

My pin repair skills are limited, I can swap a board and solder a loose wire but that's about it.

Attached some pics of the problem and the board - I see there is some crusty growth - visible in one pic.....

All advice appreciated,

Mike
 

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Quick question - have you reseated the ribbon cable? If that doesn't work it still could be as simple as replacing it which will be much cheaper than a board or board repair so maybe worth checking.
 
SpiderPin said:
Quick question - have you reseated the ribbon cable? If that doesn't work it still could be as simple as replacing it which will be much cheaper than a board or board repair so maybe worth checking.
Click to expand...
I have once - but thought that as it sorts itself after a day or two, it couldn't be a loose connection/cable?

Mike
 
I would replace the ribbon cable, it’s very common for them to give that type of fault, I’ve had it a few times.
 
Annualman said:
I have once - but thought that as it sorts itself after a day or two, it couldn't be a loose connection/cable?

Mike
Click to expand...
Could be. Ribbon cables cheap and if it isn't that you've got a spare you can use. I had an issue with Shadow that was similar to this and it was the cable - solved itself once a new one was put in.
 
Given the symptoms you describe, I think it is unlikely that the ribbon cable is the problem. To my mind, the culprit is either the DMD driver board or the DMD display itself.

I have quite a bit of experience with these (I repair boards) and sections of the DMD driver board get awfully hot. Here's a photo of one I worked on recently. Someone had already butchered it (I mean repaired it ;) ) before I got involved.

1679221553822.png

As ugly as this repair is, it shows that they can be fixed given time and effort. If the DMD display is faulty, it will need replacing. These things are 30 years old now and have done well to stand the test of time.

How would I troubleshoot this?
If you have another machine, I would suggest trying a swap of either the DMD driver board or the DMD display to see which one is the issue. Please be careful. There are high voltages (+62V, -113V, -125V) and a couple of capacitors (they hold charge even after the machine is turned off) on the DMD driver board. Please make sure that everything is turned off and discharged before working near this board.

If the driver board is faulty, you can either repair it (I'd be happy to have a look at this for you) or you could just buy a replacement. PinLed in Germany make a drop in replacement that works very well.
If the display is faulty, I wouldn't recommend trying to get an original replacement as it will already be old and have a limited lifespan. I would suggest getting an aftermarket LED replacement instead.

Let me know if you need any help.
 
Thank you all for help - I am pleased to say the ribbon cable reseat appears to have solved the problem.

Apologies for newbie info request - I will alwys try them ribbon cables first in future.

I am learning ..... if in doubt ITRCS Its The ribbon Cable Stupid.

Mike
 
Annualman said:
Thank you all for help - I am pleased to say the ribbon cable reseat appears to have solved the problem.

Apologies for newbie info request - I will alwys try them ribbon cables first in future.

I am learning ..... if in doubt ITRCS Its The ribbon Cable Stupid.

Mike
Click to expand...

Glad it was a simple fix.
 
Looking at your pictures, that crustiness on transistor Q6 may be 'heat sink compound' used to assist with heat transfer to the black heat sink. The three transistors for the display voltages do heat up, as seen by the discolouration in Ragnar's picture. The proper stuff is sticky as hell.
 
Jay Walker said:
Looking at your pictures, that crustiness on transistor Q6 may be 'heat sink compound' used to assist with heat transfer to the black heat sink. The three transistors for the display voltages do heat up, as seen by the discolouration in Ragnar's picture. The proper stuff is sticky as hell.
Click to expand...
Thanks, should I clean or just leave well alone?
 
If that's what it is, I'd leave it alone. It's not electrically conductive, and it's not as if you're likely to get it on your hands or clothing.
 
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