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(Topic ID: 312580)

Bally AS 2518-16 SDB Sparking!

By JethroP

2 years ago



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  • 8 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by JethroP
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    #1 2 years ago
    OP
     
    ???

    JethroP

    Pinside+ Frequent

    6y 101K 3,121 9 14 1

    I picked up a non working SDB. It had some burned traces and was missing quite a few parts. I replaced the missing parts and patched the missing traces. It isn't a very beautiful board, but looked to be serviceable. Hooked it up and I got immediate sparking at around J3 pins 6 and 7. Replaced the J3 header pins and almost every HV component....more than once now and same thing. Sparking. Something's wrong in the HV section....Any clue as to what could be wrong?

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    #2 2 years ago
     
    GPE

    G-P-E

    GPE

    US Omaha, NE

    13y 76,800 2,778 4

    J3-6 = HV input, J3-7 = Ground
    Check your jumper wires and make sure you clean the pins in that area good with Alcohol.

    You will also need a heatsink on that TO-220 transistor that replaced the 2N3584.

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    #3 2 years ago
     
    ???

    pins4u

    Pinside apprentice

    BW Gaborone

    3y 34,400 1,033

    The first picture is a bit blurry but it looks to me like the PCB could be a bit burnt between the pins?

    You might need to remove that connector and dremel away the frizzled PCB fiberglass base. It looks like it could have become carbonised and is conducting the high voltage.

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    #4 2 years ago
     
    GPE

    G-P-E

    GPE

    US Omaha, NE

    13y 76,800 2,778 4

    ^^ What pins4u said ^^
    Clean up that connection real well and look at it under magnification. A bit of burnt board (carbon) will add to conductivity.
    ANSI/IPC specs say you should have 15mils spacing between those two pads for voltages of 100V to 300V. That board might have 15 but cutting it close. For 300+, the spacing should be 30mils. Bally appears to be at at or under the recommended spacing between the two pads so any bit of debris or carbon build up can add to the arc over capability.

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    #5 2 years ago
    OP
     
    ???

    JethroP

    Pinside+ Frequent

    6y 101K 3,121 9 14 1

    OK, well that cured that problem. I cleaned the spaces between terminals 6, 7, and 8 on J3. Now have working displays.

    HOWEVER, when the game boots the knocker fires twice. Start a new game and ALL the solenoids seem to fire at once...maybe a couple rounds of firing twice then quit. The playfield fuse has blown, I think from too much rapid firing of the solenoids. Any advice on why all the solenoids are firing?

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    #6 2 years ago
     
    DBS

    Skidave

    Pinside member

    6y 63,550 1,285 9

    No offense, but that board looks rough on the solder side. I think it may have had a few shady repairs before you. I would think the large decoder chip is having an issue if all solenoids fire at once. Or, you have shorted transistors.

    I once looked at a SDB board for someone and anything connected to ground was blown up due to previous issues. It was not worth repairing and I handed it back. Time to get out your meter and start following the schematic for the solenoids - transistors, diodes, ICs.

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    #7 2 years ago
     
    AMS

    barakandl

    nvram.weebly.com

    12y 132K 10,412

    These 0.100" connectors have high voltage really close to other stuff. High voltage likes to arc over. Clean up that soldering. I have seen holes burnt in the board around that area. It can happen at MPU J4 43v pin when the battery leaks too.

    OP
    Quoted from JethroP:

    OK, well that cured that problem. I cleaned the spaces between terminals 6, 7, and 8 on J3. Now have working displays.
    HOWEVER, when the game boots the knocker fires twice. Start a new game and ALL the solenoids seem to fire at once...maybe a couple rounds of firing twice then quit. The playfield fuse has blown, I think from too much rapid firing of the solenoids. Any advice on why all the solenoids are firing?

    Wrong solenoids are almost always connector issue between MPU J4 and driver J4. Look for a solenoid bit to be stuck always high during solenoid test.

    If coils are locking on as soon as the power switched is thrown, the transistor or transistor array is usually the problem.

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    #8 2 years ago
    OP
     
    ???

    JethroP

    Pinside+ Frequent

    6y 101K 3,121 9 14 1

    Problem solved and board working 100%.

    I did find a bridge at J4 between pins 5 and 6. Those pads were so close, even looked like the pads were touching, no solder involved. I scraped away a little copper, eliminated the continuity between those pads, and no more issues. Thank you all for the help.

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