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DMD flicker on a WPC95 game (MB)

cooldan

cooldan

i like pizza
10 Years
Joined
Jul 21, 2011
Messages
7,149
Location
Ealing, London
a picture tells a thousand words, so i just recorded a ball on Monster Bash this afternoon:

[video=youtube;ePZs7wWGUlM]

i had a brief chat to Stan at the London show recently, and he mentioned something about a capacitor needs changing, but i can't remember what he said

thanks fellas
 
It looks almost like in the old days of CRT monitors if you had your mobile on your desk and someone txt. As the txt was receiving it would cause the screen to flicker
 
it hardly comes out at all in the vid, to be honest; something to do with the frequency of the video capture, no doubt.

i have no idea what DMD 'ghosting' is, but i don't think it's that. it just flashes all the time, and is immediately obvious to anyone looking at it, especially when compared to a fully functioning DMD like on the left and right of this game
 
Try swapping the DMD out of another game and see if it still does it (also see if the MB DMD does this in a different game).
 
You could try changing the capacitors on the dmd driver board. 2x 220uF, 160V i believe are the culprits.
 
I'd probably rebuild the whole high-voltage section on the board - only about a tenner's worth of bits.
 
Inclined to say that the HV secton on the DMD driver PCB is probably on it's way out. Less than a tenners worth of bits from Andy. About 2 hours to do the job (well I've got it down to less than 2 hours but for your first time budget 4 hours!), removing the old components, track repair (!) if necessary and install new components. Don't remove the 3 caps next to the connectors at the bottom of the board as they aren't in the new bits and the original ones should be ok (they're used to sort ghosting issues, where the display stays on for longer than it should).

Remember new DMD driver PCB's can be bought for £60 if you don't want the hastle ! :biggrin1:
 
On wpc-95 The dmd driver section is part of the audio board too. This part is VERY expensive and has only been available for a short time.

http://bayareaamusements.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=PC-A-20516

Uk supplier:
http://www.pinballdisplays.co.uk/pinballdisplays/id1.html


The two big caps you see on that board in the first link i would suspect to cause the issue in the vid, but yes, i would rebuild the HV section while at it too. If Andy sees this thread he may well chime in with the exact cause down to a tee. He's seen it all.
 
thanks fellas, all very useful.
i'll start by trying the DMD in another game, and another game's DMD in MB - hopefully i'll be able to establish that the problem lies on the MB boards

after that i'll take a deep breath and see if i can understand all that advice about stuff to test and replace
 
Rus121 said:
On wpc-95 The dmd driver section is part of the audio board too.
Click to expand...

Opps, I forgot it's a different board set for WPC-95. :tsk:

I have repaired that too, not much difference and easy enough if you know what you're doing. Difference price altogether for a new board though... :faint2:
 
that's what Matt Adams said when he was over in the Tiki Hut last night.

i'll see what i can do.
Andy, do you stock these, can you send me some and send me the bill?
 
So I changed the two big capacitors that stick out (actually Calimori did it as I watched) but the problem is still there

I haven't tried those other ideas yet about swapping out the DMD, may try that tomorrow, but in the meantime any other pointers?
 
Have you checked the capacitors are properly connected. I think some tracks are on the component side, and may not be contacting under the capacitor body.
 
I checked continuity from the legs to another point on the PCB and they were good.
We fitted them the same way the old two came off, could they have originally been in the wrong positions?
 
not yet, i will do this in a couple of hours. the only things i've tried so far are the simplest (reseat connectors) and the most complicated (desolder and replace capacitors) so i should really check that it's not the actual DMD

i will report back with results
 
It's not the DMD (phew) as it worked fine in another game, and the imported DMD had the flicker.

Anything I should try next?

These are the caps we replaced by the way

ImageUploadedByTapatalk1367578723.413758.jpg
 
cooldan said:
These are the caps we replaced by the way

View attachment 1719
Click to expand...

I would have gone for the two (slightly to the left and) above your finger that are part of the HV section.

cooldan said:
Anything I should try next?
Click to expand...

Um, let me see... :boink:

xenon325i said:
I'd probably rebuild the whole high-voltage section on the board - only about a tenner's worth of bits.
Click to expand...

Moonraker said:
Inclined to say that the HV secton on the DMD driver PCB is probably on it's way out. Less than a tenners worth of bits from Andy. About 2 hours to do the job (well I've got it down to less than 2 hours but for your first time budget 4 hours!), removing the old components, track repair (!) if necessary and install new components. Don't remove the 3 caps next to the connectors at the bottom of the board as they aren't in the new bits and the original ones should be ok (they're used to sort ghosting issues, where the display stays on for longer than it should).
Click to expand...

Rus121 said:
The two big caps you see on that board in the first link i would suspect to cause the issue in the vid, but yes, i would rebuild the HV section while at it too.
Click to expand...

Carl Spiby said:
What about swapping out the driver board from another machine?
Click to expand...

:bolt:
 
^^ What he said^^

The two big caps at the top of the board, not the ones at the bottom.
 
Thanks for the offer but my mind has moved on now, it's not that bad and this is going on site to the Pipeline anyway to make space
 
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