(Topic ID: 280540)

U20 blowing every few days - Black Rose

By DaveTheTrain

12 months ago


Topic Heartbeat

Topic Stats

  • 28 posts
  • 15 Pinsiders participating
  • Latest reply 11 months ago by Classe
  • No one calls this topic a favorite

You

Linked Games

No games have been linked to this topic.

    Topic Gallery

    View topic image gallery

    20201029_082415 (resized).jpg

    #1 12 months ago

    A recurring issue with my Black Rose.
    U20 keeps blowing. It'll work fine for anything from a day to a week then blow causing a column of the switch matrix to play up. So if you hit "top standup bottom" every switch in row 1 will activate. That happens with every switch in that column activating their respective rows.

    Its always column 4 with the jets on it and a month ago I had removed them to adjust their leaf switches.
    So i assumed it must be a short in that area? Would that blow it?
    But i can't spot anything at in that area and it doesn't explain why it can work ok for up to a week, so surely it's not constantly shorting?

    Your expertise is really appreciated. I have 9 u20 chips left...
    20201029_082415 (resized).jpg

    #2 12 months ago

    Maybe the switches (almost) touch a coil lug ?
    If the vibrations cause an occasional contact between the high voltage from the coils and the switch matrix it could cause this.

    I assume you have tried taking out and reseating U20 before changing it, just to make sure the problem isn't in the IC socket or on the PCB ?

    #3 12 months ago
    Quoted from Zigzagzag:

    Maybe the switches (almost) touch a coil lug ?
    If the vibrations cause an occasional contact between the high voltage from the coils and the switch matrix it could cause this.
    I assume you have tried taking out and reseating U20 before changing it, just to make sure the problem isn't in the IC socket or on the PCB ?

    I've replaced the chip in U20 three times and it's fixed it each time... Until it shorts again.
    Could it still be the socket?

    I feel like I'm looking for a needle in a haystack

    #4 12 months ago
    Quoted from Zigzagzag:

    Maybe the switches (almost) touch a coil lug ?
    If the vibrations cause an occasional contact between the high voltage from the coils and the switch matrix it could cause this.
    I assume you have tried taking out and reseating U20 before changing it, just to make sure the problem isn't in the IC socket or on the PCB ?

    I would agree that it seems like there is a switch wire shorting to a coil lug. Spend a lot of time really looking close at all of the coils to see if any switch wiring is in close proximity.

    #5 12 months ago
    Quoted from Eric_S:

    I would agree that it seems like there is a switch wire shorting to a coil lug. Spend a lot of time really looking close at all of the coils to see if any switch wiring is in close proximity.

    Good advice. I would also encourage you to bring in a friend or even a wife for a child to look at it as well it's amazing how another set of eyes can pick things up that you are missing.

    #6 12 months ago

    make sure the pop switch stacks have the insulating tube in them , i had a similar issue that drove me crazy.

    #7 11 months ago

    Curious what you find here. It would seem you’re getting voltage coming back to the chip somehow. At least it is a socketed chip

    If you haven’t already, you could always resolder the socket just to sure there isn’t something not visible creating a short.

    #8 11 months ago

    I would look at all the diodes, make sure none are ready to break off. Put the game into test mode and start going thru each switch individually and see what switch blows U20.

    #9 11 months ago

    I took a pop bumper out to look closely... Nothing notable..

    Games been running ok a few days now.

    I've had it running with J206 unplugged to see if something on the cpu board is blowing it, not sure it that's even possible?

    It's irritating when it seems ok, then in a few days it'll blow. At least that's whats happened previously!

    #10 11 months ago

    Ok so it went again...
    I was having the most amazing game.

    The only thing that seemed odd before I noticed certain switches not working was the bottom pop got hit and stuck on. I think the stick got lodged off off the pop bumper spoon and off the edge of the spoon so didn't push the ring back up... so the switch got stuck on.

    Would that cause something to blow?!

    #11 11 months ago
    Quoted from DaveTheTrain:

    Ok so it went again...
    I was having the most amazing game.
    The only thing that seemed odd before I noticed certain switches not working was the bottom pop got hit and stuck on. I think the stick got lodged off off the pop bumper spoon and off the edge of the spoon so didn't push the ring back up... so the switch got stuck on.
    Would that cause something to blow?!

    Yes, pop bumpers are momentary switches and if they stay energized will feed current back. Usually the coil burns up. Change your diodes, I would say they are bad, get the spoon adjusted properly. Check for broken, loose wires on all items in Column 4.

    #12 11 months ago
    Quoted from eyeamred2u:

    Yes, pop bumpers are momentary switches and if they stay energized will feed current back. Usually the coil burns up. Change your diodes, I would say they are bad, get the spoon adjusted properly. Check for broken, loose wires on all items in Column 4.

    This is true for special solenoids in some (usually earlier) System 11 machines and all System 9 and earlier machines. The special solenoids have trigger switches that are independent of the switch matrix. The trigger switch causes the solenoid to energize through HARDWARE. The solenoid stays energized as long as the trigger switch is closed. When the solenoid energizes it closes a second switch attached to the switch matrix. This second switch is detected by the software and is often referred to as the scoring switch.

    For later System 11 machines and all WPC era machines this is not true. These machines use the switch connected to the switch matrix to momentarily energize the solenoid through SOFTWARE. It is up to the software to determine how long the solenoid is energized.

    In all WPC era machines the solenoid diodes are located on the power board not at the solenoid. When Williams introduced the System 11 Auxiliary Power board that is when solenoid diodes disappeared as they were moved to the auxiliary power board.

    #13 11 months ago
    Quoted from DumbAss:

    This is true for special solenoids in some (usually earlier) System 11 machines and all System 9 and earlier machines. The special solenoids have trigger switches that are independent of the switch matrix. The trigger switch causes the solenoid to energize through HARDWARE. The solenoid stays energized as long as the trigger switch is closed. When the solenoid energizes it closes a second switch attached to the switch matrix. This second switch is detected by the software and is often referred to as the scoring switch.
    For later System 11 machines and all WPC era machines this is not true. These machines use the switch connected to the switch matrix to momentarily energize the solenoid through SOFTWARE. It is up to the software to determine how long the solenoid is energized.
    In all WPC era machines the solenoid diodes are located on the power board not at the solenoid. When Williams introduced the System 11 Auxiliary Power board that is when solenoid diodes disappeared as they were moved to the auxiliary power board.

    Thanks, I always get em mixed up, that is why I say the coil usually burns up first.

    #14 11 months ago
    Quoted from eyeamred2u:

    Thanks, I always get em mixed up, that is why I say the coil usually burns up first.

    Yes. It's easy to get confused because Williams changed their system and design a few times within the space of a few years. There's no easily identifiable consistency during the period of changeover in System 11.

    It's not personal. I just want to make sure that correct information (and therefore assistance) is provided to the person asking for the help.

    #15 11 months ago
    Quoted from DumbAss:

    Yes. It's easy to get confused because Williams changed their system and design a few times within the space of a few years. There's no easily identifiable consistency during the period of changeover in System 11.
    It's not personal. I just want to make sure that correct information (and therefore assistance) is provided to the person asking for the help.

    Glad you helped. Us old timers will not be around forever.

    #16 11 months ago

    I have learnt a few things from the previous posts but I'm still not sure if having a leaf switch permanently energised could have blown u20?

    Part of me wants it to be the problem as I fixed it sticking...

    #17 11 months ago

    Ahh the old U20 intermittent issues. Finally fixed mine on my TZ as it would blow every 3-? Games. Sometimes run days normally, then poof.

    I found the diverter coil shorting through a screw stuck in it, sending 50 volts through wire forms that destroyed the switch matrix. Long story short: is it possible you’ve got a coil power wire touching a metal bracket under the pf? Can you activate the coils while lifting up the pf? Risky but sometimes yields results. Metal bracket bent into harness?

    #18 11 months ago

    It would seem you have almost narrowed it down to the bottom pop bumper. I would
    Probably just disconnect the wires from it, (tape them off), and see if it works long-term.
    At that point you will know it is something with that switch, adjust/replace switch, diode etc.. till it works.

    #19 11 months ago
    Quoted from DNO:

    It would seem you have almost narrowed it down to the bottom pop bumper. I would
    Probably just disconnect the wires from it, (tape them off), and see if it works long-term.
    At that point you will know it is something with that switch, adjust/replace switch, diode etc.. till it works.

    Well, I'm not 100%, I still don't know if the leaf getting stuck on would cause that issue. Some people have told me its unlikely but I really hope it to be the case as I'd have solved it now.

    -1
    #20 11 months ago

    Check for a lamp socket terminal too close or touching a switch. Several years ago I had trouble with a Demo Man that kept blowing switch matrix chips every so often. I found a lamp socket terminal touching the right hand slingshot switch. I had to bend the socket terminals away slightly and place a piece of electrical tape between the socket terminals and the slingshot switch.

    #21 11 months ago
    Quoted from KenLayton:

    Check for a lamp socket terminal too close or touching a switch. Several years ago I had trouble with a Demo Man that kept blowing switch matrix chips every so often. I found a lamp socket terminal touching the right hand slingshot switch. I had to bend the socket terminals away slightly and place a piece of electrical tape between the socket terminals and the slingshot switch.

    Does it blow the column that that switch is on?
    I've tried studying all the switches on the column that ends up suffering from the u20 blowing but struggle to see anything of note.

    #22 11 months ago
    Quoted from DaveTheTrain:

    Does it blow the column that that switch is on?
    I've tried studying all the switches on the column that ends up suffering from the u20 blowing but struggle to see anything of note.

    Yes, he stated it blows Column 4. Unless he sees something touching something or a loose/broken wire, he may need to send his boards out for service.

    #23 11 months ago

    It blew again.

    I have studied under the playfield so many times. Nothing is touching or near anything on that switch collumn.
    I played a game with glass off and it was a good game... Then I noticed switches on that column weren't working and realised u20 had gone.

    I popped a new one in and played a game by rolling the ball and touching switches, i tried to do everything I had done on that last game to no avail.
    I am at a loss and have no idea how to diagnose this

    #24 11 months ago
    Quoted from DaveTheTrain:

    It blew again.
    I have studied under the playfield so many times. Nothing is touching or near anything on that switch collumn.
    I played a game with glass off and it was a good game... Then I noticed switches on that column weren't working and realised u20 had gone.
    I popped a new one in and played a game by rolling the ball and touching switches, i tried to do everything I had done on that last game to no avail.
    I am at a loss and have no idea how to diagnose this

    I'd suggest you try DNO's suggestion above and isolate single switches starting with the pops that you recently worked on by removing and taping off the wires and then play extensively until it either does or doesn't blow.

    #25 11 months ago

    Really look over the wire bundles to see if something is causing a short, like an errant screw. Any wiring hacks on the game? Look really close at those. Get a friend to look it over. A fresh set of eyes may see something you're missing.

    #26 11 months ago

    As others have said it might not be obvious. I had a similar issue with a game where a playfield screw for a spinner switch went too far through the playfield and pierced a coil wire running under the playfield. It wasn't blowing a chip, but it was causing all kinds of havoc with the display and game logic.

    #27 11 months ago

    Might be a long shot, but you can always attach pics of the suspect area. Some good close-ups, different angles. Pinsiders have a knack of spotting something out of place.

    #28 11 months ago

    I think no one mentioned that a broken U14 (U23 on WPC-S and WPC-95) can take out U20 after a while. I think that U20 normally breaks within a couple of minutes if U14 is broken, and it sounds like you can play longer than so, but it could be worth a try, changing U14.
    One way to check that there isn’t any short on the playfield is to disassemble the U20 chip, then start the game, and measure in the socket that it isn't higher than +12 VDC on any of the pins 11 to 18. If it’s higher voltage than that on any of those 8 positions, then there’s probably some type of short on the playfield. '
    If the short is intermittent, you probably won't see a higher voltage in this test, but it also could be worth a try.

    Hey there! Got a moment?

    Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside