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SEGA DMD dead?

edsr

edsr

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Oct 7, 2017
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Cheltenham
Aargh!

Left my Baywatch on while putting kids to bed etc. Came downstairs and no DMD [emoji33]

- Reboot hasn’t fixed it.
- F1 and F2 are OK (pulled one end out and checked continuity).
1 Re-seated connectors with red/black cables at both ends.
- And it’s got the 5v upgrade kit (direct from power board to dmd)

Dead.

Any suggestions guys? [emoji120]


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It need 5v and 12v well think it's 18v? if you have a ATX power supply you can power it from that to see if it's the display or supply
 
Thanks Ronnie, no other psu I’m afraid.


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I’m getting 4.95v at the smaller 5v connector on the ‘upper’ dmd board, with 4.87 on the back of the actual solder joints on the board (left). Then 4.91v and 17.88v across the larger 4 pin connector on the ‘lower’ dmd board (right)

uploads.tapatalk_cdn.com_20171110_f563bf3e6ef62e10a4f2e2c4bdca1b87.jpg


I was going to take the power board out this evening and reflow the joints on it to see if that helps. I could also try carbon paste on the pins to see if I can reduce any voltage drop.
 
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looks like your voltages are ok, was the DMD nice and bright no warm up time? could be a component on the back of the DMD which is not easy to work with
 
ronnie63 said:
looks like your voltages are ok, was the DMD nice and bright no warm up time? could be a component on the back of the DMD which is not easy to work with
Click to expand...

Thanks, yeah it was absolutely mint. Super bright, no missing pixels, then just nothing.

The thing I did consider is it’s probably the longest it’s been on standby in attract mode with all the bulbs in - maybe heat-related?


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Re-seat all of the ribbons.

DE/Sega DMDs are completely standalone units and have their own CPU, and if there's no "instruction" data getting to it from the main board CPU, it just stays switched off

Tim
 
strobey said:
Re-seat all of the ribbons.

DE/Sega DMDs are completely standalone units and have their own CPU, and if there's no "instruction" data getting to it from the main board CPU, it just stays switched off

Tim
Click to expand...

Thanks Tim, I’ve done that too. I did wonder about possibly swapping the ribbon cable out or even flipping it?


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edsr said:
I’m getting 4.95v at the smaller 5v connector on the ‘upper’ dmd board, with 4.87 on the back of the actual solder joints on the board (left). Then 4.91v and 17.88v across the larger 4 pin connector on the ‘lower’ dmd board (right)

uploads.tapatalk_cdn.com_20171110_f563bf3e6ef62e10a4f2e2c4bdca1b87.jpg


I was going to take the power board out this evening and reflow the joints on it to see if that helps. I could also try carbon paste on the pins to see if I can reduce any voltage drop.
Click to expand...
Reflowing solder joints sorted out random blacking out on my Baywatch.

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strobey said:
Re-seat all of the ribbons.

DE/Sega DMDs are completely standalone units and have their own CPU, and if there's no "instruction" data getting to it from the main board CPU, it just stays switched off

Tim
Click to expand...

Not completely correct. Yes they have their own CPU controller which must be working. But if there’s no data from the game CPU you will still see the start up message and display software version. You can try it by removing the ribbon cable from the cpu and switching on.

So if you have nothing, you either have no power or incorrect power, dead display, or defective display driver board. As you have quite a voltage drop from the connector to the back of the connector that’s the first port of call. Replace the connector header and plug on connector. You should also replace the onboard capacitor.

As the display has been working recently it’s less likely the display has died but not impossible.

I have had display driver boards due for various reasons. The last one I saw was a dead on board Crystal causing the display cpu not to run.

If you want me to check out the display driver pcb I have a working system here and can test it for you.

Also look for any signs of battery acid on the display driver board.

Andy
 
pinballmania said:
Not completely correct. Yes they have their own CPU controller which must be working. But if there’s no data from the game CPU you will still see the start up message and display software version. You can try it by removing the ribbon cable from the cpu and switching on.

So if you have nothing, you either have no power or incorrect power, dead display, or defective display driver board. As you have quite a voltage drop from the connector to the back of the connector that’s the first port of call. Replace the connector header and plug on connector. You should also replace the onboard capacitor.

As the display has been working recently it’s less likely the display has died but not impossible.

I have had display driver boards due for various reasons. The last one I saw was a dead on board Crystal causing the display cpu not to run.

If you want me to check out the display driver pcb I have a working system here and can test it for you.

Also look for any signs of battery acid on the display driver board.

Andy
Click to expand...

Thanks Andy that’s a massive help. I’ll take a look at the power board later on and reflow it. Then go from there.

So this onboard capacitor - is that on the upper of the two boards when screen is laid down face first?

I need to get some bits from you anyway (I have a growing list!) so may well pop up - I’ll PM you.


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Yes.

If you’re able to come up we can test the board while you wait. You can bring the screen too.
 
So reflowed the whole power board and still not even a flicker from the display.

I’ve also looked at the DMD driver board and all seems ok visually (apart from a couple of random capacitors on the back (is that normal ?). Is there a way to check the capacitor while it’s still on the board?

uploads.tapatalk_cdn.com_20171110_0a77e42832702dd38c400bae071ce1d7.jpg

uploads.tapatalk_cdn.com_20171110_a9f60dec22c3eaf63218613fbcddd8bc.jpg


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Tried a few other things last night but looks like either the screen or driver board is duff, from what Andy has said.

@andy, I’ve PM’d you to take you up on that offer of testing the driver board.


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Zoiks. Pray it isn’t dead otherwise things just got expensive.
 
Yep. I’ll have a crystal or capacitor please God! Cheapest new screen I can find is a Vishay for £350


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Yeah I did see some similar ones (although that looks even better still). I’m really on the fence at the moment. I was going to just clean and restore, replacing like for like and keeping it as original as possible. I’ve used normal bulbs and just cleaned what is there, putting things back to normal and tidying everything up. I kinda like the retro look.

But if the screen is fried it’s perhaps an opportunity to revamp the thing, go full on LED and colour DMD pimp the sounds up etc and make a more reliable, modern machine.

It’s weird. If I did that to a car, it’d devalue it massively and cost a lot of money - pointless. But on pinball it seems to add value to the machines. [emoji848]


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edsr said:
Yeah I did see some similar ones (although that looks even better still). I’m really on the fence at the moment. I was going to just clean and restore, replacing like for like and keeping it as original as possible. I’ve used normal bulbs and just cleaned what is there, putting things back to normal and tidying everything up. I kinda like the retro look.

But if the screen is fried it’s perhaps an opportunity to revamp the thing, go full on LED and colour DMD pimp the sounds up etc and make a more reliable, modern machine.

It’s weird. If I did that to a car, it’d devalue it massively and cost a lot of money - pointless. But on pinball it seems to add value to the machines. [emoji848]


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Click to expand...
LEDs don't automatically add value - despite what a thousand ebay sellers claim - there are lots of pinheads that hate LEDs.

All to do with the look - in home use the power/heat issue really isn't an issue.

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Thanks @Arv Good shout - double checked F3 and it has continuity, plus am getting decent voltages at the pins.

I also spent time checking the connections to the driver board. On the larger one I used a safety pin to splay the three prongs that make up the ‘male’ connectors on the board. Then on the smaller one I swapped out the tiny metal clips from inside the connector that goes onto the board using some donors from a piece I found lying around inside the cabinet. So they’re super tight now and I know it’s not a voltage-drop issue. And as there is not a glimmer from the screen, can rule out signal from cpu etc.

So I think based on Andys prognosis, it’s either the driver board or the screen. [emoji51]

@pinballmania - Am wondering if Maplin might stock the cap and/or crystal that are prone to fail on the DMD driver board so I can try those tomorrow as the next cheapest things to check before coming to see you?


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OK so re-capped C7 on the DMD controller with a new part from Maplin.

uploads.tapatalk_cdn.com_20171112_d9856562f52064ce2401a0cc95d1b33d.jpguploads.tapatalk_cdn.com_20171112_37467f3b26260b4b31a932549dc3bf75.jpguploads.tapatalk_cdn.com_20171112_bb9a419b1ada97fbed7540ba6df18b3f.jpg

And... nothing [emoji20]

If I’ve followed the guidance on here correctly, it’s either a crystal or the screen. Not looking good...

Looking at the screen I noticed this (see bottom right hand corner by the orange rubber plug thingy - assume this is where the gas is pumped in) - is that a sign the screen is shot? I think I remember it looking like that before when it was working but am not certain.

uploads.tapatalk_cdn.com_20171112_6778d090d97a0e9368a0c53172dc7200.jpg
 
What's the crystal saying when you put your meter on it?

My fluke has a Hz setting.
 
Thanks @Arv I’ve no idea how to test a crystal with a dmm. This is the meter I have uploads.tapatalk_cdn.com_20171112_2e5fa5aef955c559a0037bbb1fcd3116.jpg


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And this is the crystal.
uploads.tapatalk_cdn.com_20171112_8686b827f0ccc19d4aebb72807ec339c.jpg (top of board)
uploads.tapatalk_cdn.com_20171112_646c2e6b2b1bc119b468d177512da58a.jpg (bottom right pin is the one on the square corner of the xtal and I *think* both the bottom pins are going to gnd)


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Can't see a Hz setting on there I'm afraid.
 
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