Tales From The Crypt Display Problem....

johnsj01

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I figured where better of a place to try and find out some info and or maybe a part I need for my TFTC pinball. I powered it up the other day and everything started as it should but when I was ready to play, the Dot Matrix display had gone out (at some point it just blinked out). Everything else still works and plays as it should, but no display..... I completely unplugged it and re-plugged it back in but still nothing. I am really lost without my pin and still pretty new to this and I don't have a lot of know how on how to fix this. Any ideas or thoughts would be greatly appreciated. If there is no "easy" fix (like a bad fuse or something) and I need to just get a new display, it would be a big help if anyone is selling one or knows of the best place/deal to get one.
Thanks
 
Check your fuses with a multi meter to ensure they're good.
If the fuse is blown I believe the correct value is a .5 amp fuse.

If it blows again you most likely have a blown transistor snd/or the voltages are out of whack. Take a multi meter, set it to VDC and measure the current to your DMD (the molex connector). IIRC it's supposed to be +110VDC and -98VDC .

You can also simply try wiggling the molex connections on each end with the machine on. If the screen comes on you need to reflow the solder on that header.

Also, IIRC I believe Sterns whitestar display boards are direct drop in replacements for those. Verify with Stern.
 
If at boot-up it is displaying the version #, etc. - and then goes blank - it means your DMD is fine, but it's not receiving any signals from the mpu.

If this is the case, reseating both ends of the cable will probably "fix" it for a long time.

If you are getting no activity on the screen of any kind during boot up, it's probably a power supply issue.
 
Thanks for the info guys :) I will test the fuses and also wiggle the connections. But yeah there is nothing that starts up on the dmd when powered up. I did have an issue with the screen doing a couple of lines after it was on for awhile but I quick wiggle and everything worked fine, but not this time. I'll check the fuses and then replace the wires for the power but if these don't help, I guess I should just pick up another power supply then?
Thanks again
 
Well, if you aren't getting *anything* as soon as you turn the power on, it could also be a dead DMD. So don't jump to the power supply conclusion.

If the fuse checks out, you'll need to confirm the high power. Check it at the DMD board first. If none, go back to the power supply and check at the output pin. If you don't get proper readings at either place, it could be the power supply.

And I'm sure this isn't what you meant, but don't "wiggle" the connectors. Grab the board behind the connector with 2 fingers, then put a finger on each end of the connector, and gently rock it back and forth until it's about 90% off the pins. Then (still holding the board behind the connector) firmly push the connector back into place until it is fully seated.
 
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