(Topic ID: 254084)

No blanking, system 6. Using Pincoders ROM's to troubleshoot

By Brewchap

4 years ago


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  • 32 posts
  • 4 Pinsiders participating
  • Latest reply 4 years ago by Brewchap
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    #1 4 years ago

    This system 6 MPU board was a working board until I pulled IC7 to test on another board. I replaced the 74041N at IC7 and with Pincoder's ROM 1a I should get an alternate flashing of the top and bottom LEDs. Now all that I get is the flash of both lights, then the top light stays on. Notes below on what I get when testing

    IF YOUR BOARD FAILS THIS TEST
    ==============================================================================================

    Check the board for the following:

    1) Check for pulses (alternating high/low signals) on IC1 pin 5 (VMA). This is important
    because it shows the CPU is executing instructions.
    Pin 5 is not pulsing and is HIGH

    2) You should also be seeing pulses on IC8 pins 14,13,3.
    There is no pulsing on 14,13,3 and is HIGH

    3) There should be pulses on IC18 Pin 6 (PA4) and pin 7 (PA5). If not PIA1 *could be* bad.
    There is no pulsing on 6,7 and is HIGH. I also changed the PIA with the same results

    4) Check that PIA1 pin 39 (CA2) is high and that IC2 pin 1 is low. If not IC2 will not
    light the LEDs. There is an inverter (IC7 Pins 11:high, 10:low) between these two points
    that performs the signal transition here.
    PIA 1 Pin 39 is LOW. IC2 pulses HIGH and LOW, IC7 pin 11 is HIGH and pin 10 is LOW

    5) Check that pin 15 on IC2 is low enough to be considered a logic 0 and that SW2 is
    open. Check that R19 is 4.7k and is connecting to ground on one side.
    Not sure how to check pin 15 on a 14 pin IC. SW2 is open and R19 is correct.

    #2 4 years ago

    Test ROM 1b

    | System 6 6802/6808
    | =================
    | pin 1 GND1: low low
    | pin 2 HALT: HIGH high
    | pin 3 MR: HIGH high
    | pin 4 IRQ: pulses pulses
    | pin 5 VMA: low low
    | pin 6 NMI: HIGH high
    | pin 7 NC: Not used skip
    | pin 8 VCC1: HIGH high
    | pin 9 A0: HIGH low
    | pin 10 A1: low low
    | pin 11 A2: low low
    | pin 12 A3: HIGH high
    | pin 13 A4: HIGH high
    | pin 14 A5: HIGH high
    | pin 15 A6: HIGH high
    | pin 16 A7: HIGH high
    | pin 17 A8: HIGH high
    | pin 18 A9: HIGH high
    | pin 19 A10: HIGH high
    | pin 20 A11: HIGH high
    |
    | pin 21 GND2: low low
    | pin 22 A12: HIGH high
    | pin 23 A13: HIGH high
    | pin 24 A14: HIGH high
    | pin 25 A15: HIGH high
    | pin 26 D7: HIGH high
    | pin 27 D6: HIGH high
    | pin 28 D5: HIGH high
    | pin 29 D4: HIGH high
    | pin 30 D3: HIGH high
    | pin 31 D2: HIGH high
    | pin 32 D1: HIGH high
    | pin 33 D0: HIGH high
    | pin 34 RW: *NOTE1 high
    | pin 35 VCC2: HIGH high
    | pin 36 A12: HIGH low
    | pin 37 *NOTE2 pulses Does not alternates high/low
    | pin 38 *NOTE3 low
    | pin 39 *NOTE4 low
    | pin 40 *NOTE5 high

    #3 4 years ago

    Test ROM 1c

    unable to run because I dont have an oscilloscope and/or a logic analyser

    #4 4 years ago

    Well, I'm lost and don't know which direction to go. I've tried other 6808 chips, so I'm pretty sure thats not the problem. Any ideas to try?

    #5 4 years ago
    Quoted from Brewchap:

    This system 6 MPU board was a working board until I pulled IC7 to test on another board. I replaced the 74041N at IC7 and with Pincoder's ROM 1a I should get an alternate flashing of the top and bottom LEDs. Now all that I get is the flash of both lights, then the top light stays on.

    Your CPU chip is crashing. Either because it's flakey, or more likely, because one or more of the ROM sockets is bad. Perhaps just a weak solder joint somewhere on the MPU board.. the VMA signal is generated by IC1 whenever it places a Valid Memory Address on the address bus. If it stops doing that then it has crashed.

    #6 4 years ago

    So I should follow the VMA signal from IC1 to the ROM sockets to find where it is bad?

    #7 4 years ago

    I can push IC17 around and get the LEDs to go to solid lights or no lights at all.

    #8 4 years ago

    I buzzed out all of the ROM sockets and they look good. I guess that I could re-burn the ROMs to be on the safe side. I think that Ill take a closer look at IC7 since that is where my problems began at. I don't know very much about board work troubleshooting other than replacing parts, so I'm having a hard time understanding the troubleshooting that you suggest.

    #9 4 years ago
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    #10 4 years ago

    I found the problem. I removed the NVRAM and rebooted the MPU and the lights started alternating. Going to step two now.

    #11 4 years ago

    I have another question on ROM 2. I pass the test by testing TP4 and it should be HIGH not pulsing, . But I took it a step farther and tested the below.

    * PIA1 Pin4 - If not pulsing then replace PIA1
    This pulses

    * IC7 Pin6 - If not pulsing then replace IC7
    No pulsing

    * IC12 Pin12 - If not pulsing then replace Q5
    No pulsing

    How can I pass this test if IC7 pin 6 and IC12 pin 12 do not pulse?

    Well this has now changed to TP4 LOW with PIA1 pin4 and IC12 pin12 pulsing. however IC7 pin6 does not pulse and I just changed it and it does not pulse.

    So now something is going on with IC7 it looks like.

    EDIT: You need the driver board connected to the MPU before you run the test.

    #12 4 years ago

    Sorry for all the questions, if replacing IC7 does not fix the problem, and toning out the traces to IC7 are good.... what else would keep IC7 pin6 from pulsing?

    A system 4 board (that I thought was a 3) is doing the same thing (with the test ROM 2) as the system 6 board. It also passes the test ROM 1.

    #13 4 years ago

    Still working with the blanking, right now I can power the CPU/driver board up on the bench with the game ROMs installed, and my blanking is HIGH. Its working! But when I use the test ROM 2, the blanking is LOW. Can you explain why this is happening?

    #14 4 years ago

    Hi sorry for the delay I'll try to answer tommorow

    #15 4 years ago

    Wanted to let you know that test ROM 3 will fail if you have a NVRAM installed instead of a 5101.
    On an system 4 fail the bottom light will light up.
    On an system 6 fail both lights will light up.

    Quoted from pincoder:

    Hi sorry for the delay I'll try to answer tommorow

    Thank you very much!

    #16 4 years ago

    I tested the board in the machine just a little while ago and it did not boot up, I tested the blanking using the game ROM. I have a HIGH at 1J1 pin 37, so it shows that it should be working but it aint.

    Any suggestions to find out what is wrong with the blanking? I'm out of ideas. Anyone?

    #17 4 years ago
    Quoted from Brewchap:

    Wanted to let you know that test ROM 3 will fail if you have a NVRAM installed instead of a 5101.
    On an system 4 fail the bottom light will light up.
    On an system 6 fail both lights will light up.

    This is certainly odd behavior. The RAM and CMOS tests use the same code, just different parameters. Also, the output of the test is to light either LED, not both so I have to assume that when you see both lights it's because the test isnt booting at all. The LEDs both light upon power up and the first thing the test does is shut them off. It then proceeds with the test and displays the results..

    As for the NVRAM, it shouldn't make a difference. However, if the NVRAM chip does not have a response time at least as fast as a 5101 then its possible the test will fail. Can you send me a link to the product you are using?

    What results do you get when you run 01a-leds on the system 4 and system 6 boards? They should both boot and run. If not you may have to go back to checking solder joints, sockets, etc.

    How do you know the boards are booting the williams roms on the bench?

    #18 4 years ago

    As for the NVRAM, it shouldn't make a difference. However, if the NVRAM chip does not have a response time at least as fast as a 5101 then its possible the test will fail. Can you send me a link to the product you are using?

    I am using two difference NVRAMs. One is from https://nvram.weebly.com/ and the other I think is from https://www.pinitech.com/products/5101_nvram.php.

    What results do you get when you run 01a-leds on the system 4 and system 6 boards? They should both boot and run. If not you may have to go back to checking solder joints, sockets, etc.

    Both boards alternate the LED flashing

    How do you know the boards are booting the williams roms on the bench?

    Per a Clay H. repair guide, he suggest to install a led and a 150 ohm resister to 1J1 pin 37 to add a blanking signal so you will know when you have a good blanking seen at a quick glance.

    #19 4 years ago

    Here is a picture of the LED on the driver board
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    20191026_195758 (resized).jpg20191026_195758 (resized).jpg
    #20 4 years ago

    I skipped from "it was a working board until I pulled IC7"...to the end.
    Clearly, one could easily conclude that when you pulled IC7, that wasn't quite successful.
    Pulled trace, pulled through-hole, solder blob?
    --
    Chris Hibler - CARGPB #31
    http://www.ChrisHiblerPinball.com/Contact
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #21 4 years ago

    Yes sir, I found that problem in post 10. It was a NVRAM that I think came from Pinitech. Once I changed that out to a 5101 the test ROM1A started working.

    #22 4 years ago

    Good deal.
    I don’t use the ROMs you are testing with. I’m so familiar with Leon’s that I don’t want to change


    Chris Hibler - CARGPB #31
    Http://chrishiblerpinball.com/contact
    http://www.PinWiki.com/ - The new place for pinball repair info

    #23 4 years ago

    I found last night that I had a bad power supply, after swapping that out, both boards booted in game. Still dont understand why the blanking failed on test ROM 2. I still have some issues with the system 4 board though.

    #24 4 years ago

    Now that you have swapped the power supply could you please run the 03-cmos tests again with each of those NVRAM chips?

    Also, is IC7's output to the blanking timer good now?

    #25 4 years ago

    It was the test ROM 1A that I had problems with using the NVRAM. Are you thinking that the bench power supply is difference than the power supply in the game?

    Ill have the results shortly.

    #26 4 years ago

    Both system 6 and 4 boards now pass the test ROM1A in the machine.

    Both system 6 and 4 boards do not pass the test ROM 2 in the machine. There is no pulsing on IC7 pin6. The only exception is the system 6 board. With the Flipper 2 chip install, there is pulsing on IC7 pin6. Not on the test ROM 2 chip.

    #27 4 years ago

    A strange problem with the system 4 board. After it boots, it shows that it is on ball 4 and the credit number is rolling from 01 to 23 over and over non stop.

    Also on the system 6 board, I can start a game, but the game never ends. It keep going and going, ball, after ball. Like that damn rabbit you see on TV.

    #28 4 years ago
    Quoted from Brewchap:

    A strange problem with the system 4 board. After it boots, it shows that it is on ball 4 and the credit number is rolling from 01 to 23 over and over non stop.
    Also on the system 6 board, I can start a game, but the game never ends. It keep going and going, ball, after ball. Like that damn rabbit you see on TV.

    System 4 is stuck in audit mode it's showing you the results of the audits.

    System 6 probably needs its ram reset, the balls to play is supposed to be capped at 1-9, but if it's zero, you will get endless balls. There's no bounds checking when it reads the # of balls to play, just when you set it. Going in to the setting for balls in play and cycling it through a full cycle should fix that.

    Williams really needed a way to re-load cmos defaults other than a battery pull, or putting a different set of roms in there (which "should" reset it, but doesn't always)

    #29 4 years ago

    If the system 4 is stuck in audit mode, how do I get it out of that mode?

    #30 4 years ago

    The advance button is not getting its signal to where it needs to be or its stuck.... double check it's on the correct header, IIRC it's one of the upper 2 4 pin ones on the mpu.

    #31 4 years ago

    Yes it was in the correct location. Removing the connector and then booting the pin, the credit numbers show 1 and the ball number shows 4. But no more rolling, unless I add the connector back, then it starts rolling numbers non stop, Even if you pull the connector again, it's still rolling.

    #32 4 years ago

    Thank you #slochar! I'm going to start a new thread for the audit problem.

    https://pinside.com/pinball/forum/topic/disco-fever-stuck-in-audit-mode#post-5279102

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