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#4 Bally Strikes and Spares

Discussion in 'The Menace Files' started by Menace, May 21, 2013.

  1. Menace

    Menace Well-Known Member
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    Today's installment is unfortunately going to be pretty much all text, because I haven't been taking any pics of this game. (I honestly never expected it to become part of this section if that is any indication) I have been working on this game on and off for a few months at a friends, and it's just been one of those games that I knew I didn't want to work on right from the start. (I think I've used the words "bain of my existence" on more than one occasion when talking about this game among friends) This thread will be an on-going saga as things progress and I will update it as things develop, but let me give you some of the back story...

    This game was purchased in a complete project state. What I mean by this is the previous owner at some point decided he would attempt to resurrect this game, shop it out and do whatever with it after that. The reason I wasn't thrilled about tackling this one is the game was already partially disassembled by the time the current owner got his hands on it. The topside of the PF was almost completely torn down. The underside of the PF had 98% of the bulbs removed, flipper coils had been cut out, some of the mechs hanging by the wires, some mechs are missing, some mechs are missing pieces here and there. The good thing is the BG is great, the cab is ok, and the PF is decent. Now according to the previous owner, most of the parts that he removed *should* be in one of the many bags of parts and pieces that accompanied this machine, but I'm pretty sure he didn't remove everything that is missing. Nothing is labelled or sorted, just a big pile-o-parts. The game wouldn't power up because it required a new PS board, but it came with two MPU's one of which was apparently tested working at some point, but not by me or the new owner. Sounds like good times right? You can imagine my enthusiasm for this project. :FP:

    So first things first, we replace the power supply PCB with one of Jim's @ Rottendog Amusements because we like Jim and he makes good stuff. (Ed @ GPE's version of this board is also fantastic but not always available) I don't have any pics of this process on this game, but I will be posting pics of replacing this same PCB on another upcoming thread, so not to worry. Basically remove one wire at a time from the back of the original PCB and swap it over to the new PCB, and then mount it into the original location in the game. Power it up with ONLY the J2 connected and test all of the voltage test points to verify everything is good, which it was. Then the best thing to do is replace and re-pin the 3 connectors that attach to this board, as I have yet to see a game that doesn't require this. Do this one pin at a time to minimize mis-wiring the new connectors, and pics help with checking your work when done.

    Once the re-pinning was complete, only connect J2 and J1 on the power supply, and J3 and J4 on the solenoid driver PCB. All other connectors in the head should still be disconnected. The voltages used to power the 12v and 5v on the MPU go through the driver PCB first and you want to ensure these are all correct before powering up the MPU. During this portion I found the high voltage section of the driver PCB (to power the displays) had an issue. There are two Hi-Voltage test points on the driver, and these two should measure different (TP4 around 240V and TP2 under 200V) but when something fails in this section of the PCB (which is often) they test at the same voltage, and in this case they were. First thing to check and adjust is the trim pot which I verified was the failed component. Given its age and original quality being low, it literally fell apart when I adjusted it. Replaced it with a standard single turn pot and it solved our HV section issue. Dialed the pot in so the test points were 240V and 180V. TP1 and TP3 came in at around 5VDC and TP5 around the 12VDC mark. With the other voltages on the driver checking out ok, it was time to connect J4 on the MPU to see if the game would boot.

    I will continue this post with what happened after connecting the MPU a little later on… (This game should have been called "Tits and Balls" btw, and I will definitely be adding some pics)

    D
     
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  2. DRANO

    DRANO Well-Known Member

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    Here you go Doug... I fixed it for ya.
    They had a 10' tall version of this backglass in Allentown!
    Now, make sure you include a nice close-up of that left playfield plastic on the next post :D
     

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  3. mwong168

    mwong168 Administrator
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    [​IMG]

    Would love the backglass for wall art in my game room and thanks for these write ups Doug.
     
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  4. Monkeybug

    Monkeybug Active Member

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    That game sounds like a real pain in the ass to work with. I hope you are charging the guy double!

    Here is a picture of Menace (Santiago) at work, diagnosing a problem with large screen schematics.
     

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  5. flyer666

    flyer666 Member

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    The only thing his diagnosing is how much longer before he reaches the bottom of the beer.......

    Drink up :D :D :D
     
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  6. REVOLUTION

    REVOLUTION Administrator
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    drinking + pin repair is not recommended nor endorsed by Pinball Revolution, LLC and should only be done by a trained professional. :D
     
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  7. Menace

    Menace Well-Known Member
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    You know... having the schematics up on the big screen was fantastic. Made things easier to explain and have my side kick help with troubleshooting.

    D
     
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  8. mwong168

    mwong168 Administrator
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    You mean top up your beer glass or google other schematics? :lol:
     
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  9. Menace

    Menace Well-Known Member
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    Alright, so up to this point we've replaced the power supply, connected the driver PCB, verified there was an issue with the HV section and repaired that, and then verified that all of the test points on the SDB were within spec. With that it was time to add the MPU to the mix and see if it boots.

    To do this you only have to connect J4 on the MPU (lower left), leave all the other connectors off at this point. We powered the game up with the first MPU and the LED locked on right away which means it's not booting at all (not uncommon). No biggie, this MPU looked suspect to begin with as it was rough... really rough. Lots of previous acid damage and suspect repairs, and we had a nice clean spare and apparently working MPU that came with the game, so we toss that one in (swapping the 2 game ROMS over first) and same thing! Grrrrr....

    While I'm sitting there scratching my head staring at the locked on LED of the second MPU, I suddenly smell the *magic smoke* and quickly shut the game down. WTF!?! A quick inspection reveals that U15 on the MPU had self destructed for some reason. (the IC body cracked - very very small but it was there) I grabbed the first MPU and checked U15 and sure enough it too was beginning to show signs of failure. W T F!!!! Needless to say I was pissed, as the only thing that could have caused this was over-voltage. But I had verified all the voltages being produced on the SDB were already good? I bust out the DMM and check again. Sure enough the 5V somehow managed to crank itself up to 15VDC!!!! :FP:

    So back to troubleshooting the SDB, I start looking at the section that takes care of the 5V (the area in the upper right hand corner by J3) and nothing is immediately obvious. There are not too many components in the 5V section, so I start testing all of the resistors to verify none are out of spec or gone open and sure enough one of them has failed (R50). Turns out the part had cracked causing an intermittent open in the circuit but without testing it you'd never know it was bad to look at it. Once I actually touched the part it crumbled away. DOH! Installed a new 2.2R resistor, fired the game back up and the 5V was once again within spec.

    Now to repair U15 on the better of the 2 MPU's. De-solder U15, install a socket and replace U15 with the suggested 7437 as the original MC3459 is NLA. Toss the MPU back in the game, fire it up and the damn thing is still locked on. U15 is not getting hot, no magic smoke, and the 5V is right where it should be so this part is good. Time to troubleshoot the boot process.

    Here's a quick list of what each flash means during the boot process on classic Bally and Stern games;

    Flicker: MPU reset good, program booted.
    1st Flash: ROM Checksums OK
    2nd Flash: U7 6810 ram OK
    3rd Flash: U8 5101 ram OK (U8 & U13 on mpu-200)
    4th Flash: U10 PIA OK (see details for caveats)
    5th Flash: U11 PIA OK (see details for caveats)
    6th Flash: U12 555 Display interrupt timer OK
    7th Flash: Zero crossing interrupt detector OK (solenoid voltage present)

    Where we weren't getting even the first flicker, the MPU was not resetting and booting the program. So referring to my handy notes (thanks Clay!) here's what I try;
    -Short pins 40 and 39 momentarily on the cpu chip (U9); after doing so, see if the LED goes off. It does not, so that pretty much rules out the reset section being bad.
    -Put DMM on pin 40 of the cpu and it should read 5v, and in most cases if it does the reset is good and it was reading 5V. So power the game down, and with the DMM still on pin 40 power the game on, you should see this circuit go from 0VDC and then go high approximately 50 milliseconds later to 5VDC which it does and confirms the reset section is functioning correctly.
    -From here used my DMM to check U9 pin 3, 36, and 37 to check for clock signal (I didn't have my logic probe or o-scope with me) but with a DMM the voltage will show between 2.5-2.9 volts. I was seeing 5V, so something was wrong up stream.

    This is where the big screen schematics came in from the pic posted earlier. Where we had previously done work on U15, that is where I chose to start looking. After a bit of studying, and probing around the PCB for various voltages I determined there was a break on one of the clock buffer pins of u15. All of the traces rang out on the solder side of the board but I missed a trace on the top side of the PCB! Added a jumper wire to repair the broken trace, tossed the MPU back into the game fired it up and........


    The game still didn't boot. :(
    But... the good news is the MPU was no longer locked on and we got the initial LED flicker! HUZZAH!! :cool:

    With the MPU at this stage it's at least resetting and trying to access the game program. I'll update this thread with what happened next in a little bit.

    D
     
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