(Topic ID: 234435)

WPC DMD Driver Board not working?


By Genjuro

4 months ago



Topic Stats

  • 44 posts
  • 13 Pinsiders participating
  • Latest reply 4 months ago by PinballManiac40
  • Topic is favorited by 2 Pinsiders

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    62 v section shorted on DMD (resized).jpg
    20190123_183632 (resized).jpg
    Display voltages (resized).png
    20190122_002248 (resized).jpg
    20190122_002235 (resized).jpg

    #1 4 months ago

    Hey pinside, my DMD went out on TAF. Tried a DMD I had from StTNG, and same issue, no power at all on the DMD.

    Had a blown 3A fuse (lower on the board) and replaced it... still no power.

    Think its the ceramic block (sorry i dont know if it's a resistor or whatever) near the power connector? Looking at the back of it the board is near black from a lot of heat.

    20190122_002235 (resized).jpg20190122_002248 (resized).jpg
    #2 4 months ago
    Quoted from Genjuro:

    Hey pinside, my DMD went out on TAF. Tried a DMD I had from StTNG, and same issue, no power at all on the DMD.
    Had a blown 3A fuse (lower on the board) and replaced it... still no power.
    Think its the ceramic block (sorry i dont know if it's a resistor or whatever) near the power connector? Looking at the back of it the board is near black from a lot of heat.
    [quoted image][quoted image]

    Download the manual over at ipdb.org. Go to the schematics in the back. I think somewhere in there it will tell you the voltage values you should be reading at the IDC pins on the DMD. Verify you are getting those values and let us know what you find!

    #3 4 months ago
    Quoted from NPO:

    Download the manual over at ipdb.org. Go to the schematics in the back. I think somewhere in there it will tell you the voltage values you should be reading at the IDC pins on the DMD. Verify you are getting those values and let us know what you find!

    Thanks..hopefully it has some instructions that help me figure out what you just said in the second half of your comment. I really dont know how to use this overly robust meter i own. Lol

    #4 4 months ago

    You will need to check the correct voltages are being sent to the display. Plenty of troubleshooting information to walk you through it here: http://pinwiki.com/wiki/index.php?title=Williams_WPC#Testing_DMD_Controller_Power

    #5 4 months ago

    Start by taking your meter and setting the selector to Voltage (DC). Then place the black lead of the meter firmly under the braided wire in the backbox (Ground) or use alligator clips to make a secure connection to the braided wire. You now have ground on the black wire.

    Now go to the back of the dmd display, and measure the voltages on the pins where the cable from J604 on the display driver board is attached.

    Place the red lead on pin 1 (Orange), and write down the value measured (Should be very close to -125 V or -112V)
    Place the red lead on pin 2 (Blue), and write down the value measured (Should be very close to -113 V or -100 V)
    Place the red lead on pin 6 (Gray), and write down the value measured (Should be very close to +5 V)
    Place the red lead on pin 7 (Gray/Yellow), and write down the value measured (Should very be close to +12 V)
    Place the red lead on pin 8 (Brown), and write down the value measured (Should be very close to +62 V)

    NOTE: If -125 is measured on pin 1, Pin 2 needs to measure about -113. But if -112 is measured on Pin 1, Pin 2 needs to measure about -100. The important thing here is that the difference between Pin 1 and 2 is 12VDC.

    I bet one or more of the voltages are way off or missing. But report back with your measurements... It could very easily be one of the "big white" resistors on the display driver board.

    Display voltages (resized).png

    #6 4 months ago

    Wow super helpful information the both of you. Once i get settled i will perform and post back. Thank you!

    #7 4 months ago
    Quoted from Genjuro:

    Wow super helpful information the both of you. Once i get settled i will perform and post back. Thank you!

    It appears you're unfamiliar with using a meter. Please be careful as the voltages produced foe the DMD are not trivial... over 100 volts DC. Also be very precise with your meter lead olacement. If you still have IDC connectors (the kind where the wire is pushed in from the top) then keep the connector on and test by pushing your meter lead into the top...you should be able to touch the wire blades that make contact with the wires. Much easier and much safer than trying to put your lead on a header pin. One slip and you bridge two pins with your lead and cause more damage than you already have.

    #8 4 months ago

    Thanks for the advice. While I have limited knowledge on the specific testing of pinball circuits, I know just enough to be dangerous. Definitely wanted to know if it was better to use the ground look rather than the ground wires on the connector.

    Generally I hire out electrical work on my house because I know that my insurance isnt going to be very happy with me if I burn my house down.

    #9 4 months ago

    Okay, i have basically zero reading on the three high voltage leads. These are DC right? The meter shows some millivolts... but that is it. I have 12.33v on gray/yellow and 4.9v on gray.

    #10 4 months ago
    Quoted from Genjuro:

    Okay, i have basically zero reading on the three high voltage leads. These are DC right? The meter shows some millivolts... but that is it. I have 12.33v on gray/yellow and 4.9v on gray.

    Yes, DC....Time to check your AC incoming and your fuses.

    https://www.ipdb.org/files/20/Bally_1992_The_Addams_Family_Manual.pdf

    Goto page 3-20 (PDF page 122). Check all those voltages. Check fuses F601 and F602 on DMD Controller.

    Note: For AC, put your Red and Black leads across both that say 80V and then 100V. Do not keep your black lead on ground.

    #12 4 months ago

    Good resource to have. In this case, the OP swapped DMD boards to no effect. This looks to be a voltage issue.

    #13 4 months ago

    Okay, so I discovered that the resistor still reads 4.8k ohms. Not sure if that helps.

    Ill check the ac voltage now.

    #14 4 months ago

    Is the plug in the bottom of the cabinet plugged in? It’s the purple wires

    #15 4 months ago

    108v on violet and 86v on white.

    #16 4 months ago

    I have had it unplugged before and that caused that issue

    #17 4 months ago
    Quoted from tonyhoff1:

    I have had it unplugged before and that caused that issue

    Would the voltages i just read be zero if it was? The led on the board is still lit.. not sure where that power comes from though

    #18 4 months ago
    Quoted from Genjuro:

    Would the voltages i just read be zero if it was? The led on the board is still lit.. not sure where that power comes from though

    No, the plug is for the AC voltage from the transformer. If you're reading AC then that's ok.

    Did you check the two fuses? These feed the Bridge Rectifiers on the board to convert the AC to DC through BR1 and BR2.

    If the fuses are OK, set you meter to DC, and check across the capacitors C4 and C7, then R12 and R13.

    Note: I'm going by a WPC Schematic for BSD (I have a printed set) which should be similar, but if you note any inconsistencies in the device numbers, let me know.

    #19 4 months ago

    I see all kinds of cracked solder joints on those transistors. You'll need to clean and use flux for them to accept solder. Many times, that's it. Also, looks like your're missing a chip there . For the money, just throw in a new DMD controller.... this one is a little crispy

    #20 4 months ago
    Quoted from castlesteve:

    I see all kinds of cracked solder joints on those transistors. You'll need to clean and use flux for them to accept solder. Many times, that's it. Also, looks like your're missing a chip there . For the money, just throw in a new DMD controller.... this one is a little crispy

    Could be a possibility too, but that boards nowhere near crispy....every HV section on a WPC looks like that And no, no chip missing....U12 isn't used.

    #21 4 months ago

    Fuse 601 was blown, so that indicates something behind it is over drawing current right?

    Going to follow the traces and see what is next line.

    #22 4 months ago
    Quoted from Genjuro:

    Fuse 601 was blown, so that indicates something behind it is over drawing current right?
    Going to follow the traces and see what is next line.

    Most of the time. Sometimes, very rarely, the fuse is just old and a small spike in voltage takes a fuse out (we are talking years-old fuses). If you put a new fuse in, and it blows within the week, something isn't right.

    #23 4 months ago
    Quoted from Genjuro:

    Fuse 601 was blown, so that indicates something behind it is over drawing current right?
    Going to follow the traces and see what is next line.

    Br1 and c4 are next in line. Either can short...if the caps look original id replace them. The BRs are the IC style and rarely go. You can rebuild the HV section for about $30 in parts if you're handy with a solder iron. I just did one last week.

    #24 4 months ago

    My guess is that the capacitor is the issue... but testing both with a meter, is that possible? While on, off?

    I can solder halfway decently, and usually without destroying traces.

    #25 4 months ago

    Desolder 1 leg and test with a meter. If you don't have a meter that can measure capacitance you're only going to be able to test if it's not all bad

    https://www.ifixit.com/Wiki/Troubleshhoting_logic_board_components

    Scroll down to testing

    #26 4 months ago

    thanks!

    #27 4 months ago

    No problem....if you decide to rebuild the HV section, here's the parts list. Ed at GPE doesn't assemble the kits anymore, but you can order all the components separately from his site.

    https://www.greatplainselectronics.com/proddetail.asp?prod=WPC-HVP-KIT

    Be sure to get the optional filter caps C4 and C7.

    #28 4 months ago

    High Voltage repair kits...

    http://LockWhenLit.com/products.htm

    Although on the lesser end of soldering skill level, installing the kit shouldn't be attempted unless you're completely confident in your ability to do it correctly.

    --
    Rob Anthony
    Pinball Classics
    http://LockWhenLit.com
    Quality Board Work - In Home Service
    borygard at gmail dot com

    #29 4 months ago

    Not to overcomplicate things, just a polite piece of advice. If this comes down to desoldering and soldering new pieces in, a desoldering gun should be used to minimize board damage (lifting traces).

    Best to either work on a spare board and ensure you know how to properly use a desolder gun, or send it to a professional like Rob (above) or Chris Hibler who both are well qualified to do the job right.

    Again, not trying to discourage DIY work, more like issuing friendly advice and make sure your skill sets are ready to do this.

    Another option is to buy the Rottendog board as Phat_Jay suggested earlier and sell your old board off for rebuild and keep it alive in the community.

    #31 4 months ago
    Quoted from NPO:

    Not to overcomplicate things, just a polite piece of advice. If this comes down to desoldering and soldering new pieces in, a desoldering gun should be used to minimize board damage (lifting traces).
    Best to either work on a spare board and ensure you know how to properly use a desokder gun, or send it to a professional like Rob (above) or Chris Hibler who both are well qualified to do the job right.
    Again, not trying to discourage DIY work, more like issuing friendly advice and make sure you r skill sets are ready to do this.
    Another option is to buy the Rottendog board as Phat_Jay suggested earlier and sell your old board off for rebuild and keep it alive in the community.

    Good Advice....I've been soldering for 20+ years, and I just recently bought a nice desoldering station. Makes life SOOOOOO much easier. Right tool for the job. I used to use the plunger suckers or solder tape, and can't tell you how many times I had to fix my own repairs. Now, I'm pretty confident in tackling any job.

    Rob,

    Somehow need to get your site into google searches. I literally started a thread a few weeks ago about who sold the kits anymore, since I knew Ed stopped. Crickets, and not once did your site come up under my google searches. Would have considered buying the kit from you had I known!

    #32 4 months ago

    This community is definitely why pinside rocks! Thanks a bunch guys.

    Of note, I agree that a de-soldering station would be ideal. That being said, I took the board to a gentleman that knows his stuff and has the needed equipment with information found here from the help you all gave me. Also, he has been interested in the opportunity to expand his business into pinball board repair. He does full time repair on various electronic components.

    #33 4 months ago
    Quoted from Genjuro:

    Also, he has been interested in the opportunity to expand his business into pinball board repair. He does full time repair on various electronic components.

    Very niche market and most that are qualified are normally backed up in orders. Another name would be very well welcomed into this community.

    #34 4 months ago
    Quoted from robertmee:

    I literally started a thread a few weeks ago about who sold the kits anymore, since I knew Ed stopped.

    Actually - I didn't stop selling these kits but don't get much time to make more kits. I did list 100 of them when I reopened on January 7th. 100th kit was sold on the 21st. When will I be able to make more? No idea...

    Ed

    #35 4 months ago
    Quoted from G-P-E:

    Actually - I didn't stop selling these kits but don't get much time to make more kits. I did list 100 of them when I reopened on January 7th. 100th kit was sold on the 21st. When will I be able to make more? No idea...
    Ed

    Wow....100 kits in 14 days. Apologies Ed...from your post a few weeks ago about your other job keeping you long hours that you don't have time to make kits anymore and you thought about removing the links, I incorrectly assumed that was a permanent decision.

    #36 4 months ago

    Put in a ColorDmd and unhook that board

    #37 4 months ago
    Quoted from hailrazer:

    Put in a ColorDmd and unhook that board

    This is a great idea... just need a few hundred dollars more. Lol

    #38 4 months ago
    Quoted from Genjuro:

    This is a great idea... just need a few hundred dollars more. Lol

    Shit. That's a fantastic idea!! Looking at your collection, $400 should be couch cushion change to make this problem go away!

    #39 4 months ago
    Quoted from NPO:

    Shit. That's a fantastic idea!! Looking at your collection, $400 should be couch cushion change to make this problem go away!

    Hah, point taken but countered with the fact that my collection is why I am not upgrading to a color DMD.

    #40 4 months ago

    Looks like something on the dmd itself may have caused the problem. On the positive brown wire on the original dmd to ground i am reading 100 ohms... on the known good dmd to ground i am reading open loop.

    Thinking something on the dmd shorted and overdrew current, causing the safety resistor and fuse to blow on the driver board.

    Thoughts?

    #41 4 months ago
    Quoted from Genjuro:

    Looks like something on the dmd itself may have caused the problem. On the positive brown wire on the original dmd to ground i am reading 100 ohms... on the known good dmd to ground i am reading open loop.

    Possible. What brand is the DMD? Make sure you are testing resistance with the DMD power connector unplugged. I can see if I have the same brand DMD to compare to.

    #42 4 months ago

    Here it is.

    20190123_183632 (resized).jpg
    #43 4 months ago

    Turns out it was definitely the DMD. The 62v brown lead. After getting the safety resistor replaced for a second time, I plugged it into the other DMD and everything is back to working.

    Thanks to everyone that helped get this working. Hopefully this will help someone else in the future.

    #44 4 months ago

    62 v section shorted on DMD (resized).jpgI just measured a good babcock DMD and my 62v pin to ground measures 3 meg ohm. That 100 ohm tells me there is either shorted 2 diodes/2 transistors and/or one or more of the 4 ICs for the columns shorted. I had just repaired one a year ago that had this problem with the parts mentioned.

    Oddly enough, the Babcock, Chetry and Vishay DMD schematics are in pretty much in every DE game manual.

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