(Topic ID: 246181)

WMS S3-7 Driver Board Troubleshooting


By Cheddar

3 months ago



Topic Stats

  • 17 posts
  • 5 Pinsiders participating
  • Latest reply 3 months ago by Cheddar
  • Topic is favorited by 2 Pinsiders

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    #1 3 months ago

    I have 2 sys7 driver boards that prevent the mpu from booting.

    When booting the blanking signal goes high and then back to low. Sometimes I can hear the relay click.

    Using the pincoder blanking test I get a pass on the mpu itself and a fail with the driver board connected?

    So could be 2 issues?
    1. Something in the blanking circuit is pulling the signal low
    2. Something on the board is crashing the running program and it stops feeding the clock and blanking stop.

    I did see a suggestion that you could leave the board powered up and see if any of the ics heat up.

    Or look for damage and remove the ics in that circuit.

    Any tips or tricks to try here?

    #2 3 months ago

    Take a look at pin 37 and associated traces, check it's continuity between boards

    #3 3 months ago
    Quoted from CanadianPinball:

    Take a look at pin 37 and associated traces, check it's continuity between boards

    The interconnect has been replaced. I see the same signal go high and then low on the driver board.

    #4 3 months ago

    Does the LED indicator give you a code?

    #5 3 months ago
    Quoted from FatPanda:

    Does the LED indicator give you a code?

    Zero then blank.
    I have test ROMs. The Pia's passed the Leon and Marco tests

    #6 3 months ago

    I'm curious what the minimum set of.components would.be to get a boot here. If I had a board with an interconnect, the pull-up buss and PIAs would it be enough to boot?

    #7 3 months ago

    OK first lesson for myself is make sure your MPU is booting on it's own. I thought the 6808 was good but swapping in another got it to boot with a known good driver board. It still fails with the old driver board though so I'm still looking for tips

    #8 3 months ago

    Still Chasing it down. I made a mapping of the pins on the Interconnect to the pins on the unused connector on the lower right of the system 7 mpu. This is a good way to maintain continuity across the interconnect. There are 7 pins that don't pair between the 2. 5 are unused and the other 2 are mapped back to the source of the signal.

    I find it's easier to just drag the lead of your dmm across the top of the buss pull up resistors until you get tone.

    https://docs.google.com/spreadsheets/d/1c9GLZftbifx-zvmcVz1-7EpUwzXxFPx8qpzGS2XhVSs/edit?usp=sharing

    #9 3 months ago

    So...you must have a System 7 MPU connected since it has the 7 segment display.
    When you press the lower diagnostic button, does the 7 segment display go blank, and then cycle 1, 2, 3, indicating that all three memories are working?
    --
    Chris Hibler - CARGPB #31
    http://www.ChrisHiblerPinball.com/Contact
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #10 3 months ago
    Quoted from ChrisHibler:

    So...you must have a System 7 MPU connected since it has the 7 segment display.
    When you press the lower diagnostic button, does the 7 segment display go blank, and then cycle 1, 2, 3, indicating that all three memories are working?
    --
    Chris Hibler - CARGPB #31
    http://www.ChrisHiblerPinball.com/Contact
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    So the diagnostic button does nothing. I can see activity on the data lines so I believe it is running.

    I am further believing this is at least partially an mpu issue. Without the driver board connected I can put 5.13 volts in and read 3.9 at the test points. Something is shorted somewhere. On a 10 minute test the CPU gets warm but not hot to the touch. Nothing else is heating up. I have some new CPUs coming in so I'll compare when the arrive.

    How hot is acceptable for a chip. Should it always remain cool or touchable?

    #11 3 months ago
    Quoted from Cheddar:

    So the diagnostic button does nothing. I can see activity on the data lines so I believe it is running.
    I am further believing this is at least partially an mpu issue. Without the driver board connected I can put 5.13 volts in and read 3.9 at the test points. Something is shorted somewhere. On a 10 minute test the CPU gets warm but not hot to the touch. Nothing else is heating up. I have some new CPUs coming in so I'll compare when the arrive.
    How hot is acceptable for a chip. Should it always remain cool or touchable?

    what kind of power supply are you using? the WMS MPU+driver has a big enough load the 5v would drop way down when using an old ATX PC power supply to the point the system locks up.

    The 6808/6802 CPU is usually the hottest IC chip on the those boards. I don't know exact temps but they can get warm to the touch almost to the point its uncomfortable to touch after a few seconds, but not burning you.

    #12 3 months ago
    Quoted from barakandl:

    what kind of power supply are you using? the WMS MPU+driver has a big enough load the 5v would drop way down when using an old ATX PC power supply to the point the system locks up.
    The 6808/6802 CPU is usually the hottest IC chip on the those boards. I don't know exact temps but they can get warm to the touch almost to the point its uncomfortable to touch after a few seconds, but not burning you.

    Great info! Thanks. I had a meanwell but it hiccupped and I'm trying to fix it. I am using an ATX while I troubleshoot.

    I'll let it run for 30 minutes and see how hot it gets

    #13 3 months ago
    Quoted from Cheddar:

    Great info! Thanks. I had a meanwell but it hiccupped and I'm trying to fix it. I am using an ATX while I troubleshoot.
    I'll let it run for 30 minutes and see how hot it gets

    that atx power supply may very well be the issue. The one I was using couldnt handle the 5v load of the WMS MPU and driver at the same time.

    Ive got a 12vdc and 5vdc meanwell switching power supply on the bench I use. Despite the cheap ass Chinese caps in it, its run for years of power on time and has no trouble powering both a WMS and Driver at the same time.

    #14 3 months ago
    Quoted from barakandl:

    that atx power supply may very well be the issue. The one I was using couldnt handle the 5v load of the WMS MPU and driver at the same time.
    Ive got a 12vdc and 5vdc meanwell switching power supply on the bench I use. Despite the cheap ass Chinese caps in it, its run for years of power on time and has no trouble powering both a WMS and Driver at the same time.

    How far over 5V do you have the meanwell to handle the load?

    #15 3 months ago

    30 Minutes on the ATX and the mpu didn't get any warmer. It was warm to the touch but not too bad. VDC drops to 3.2 with the driver board attached

    #16 3 months ago
    Quoted from Cheddar:

    How far over 5V do you have the meanwell to handle the load?

    i get very little voltage drop with the load of a WMS MPU and driver powered by the meanwell switcher supply. I think its rated 8a on the 5v and 2a on 12v. It comes in right near 5vdc.

    #17 3 months ago
    Quoted from barakandl:

    i get very little voltage drop with the load of a WMS MPU and driver powered by the meanwell switcher supply. I think its rated 8a on the 5v and 2a on 12v. It comes in right near 5vdc.

    I've got the RQ-50B and it does 6A on the 5V line

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