(Topic ID: 62419)

Bally AS 2518-54 Power Module Rebuild

By Fanatic

6 years ago

Topic Stats

  • 21 posts
  • 6 Pinsiders participating
  • Latest reply 6 years ago by Fanatic
  • Topic is favorited by 8 Pinsiders


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    #1 6 years ago

    Hello all,
    I'm rebuilding the Power Module for my game. Electronics is a new field for me so I hope to submit photos for critical analysis and feedback in order to improve my technique.

    My main concern is whether I have properly mounted BR1 and its accompanying heat sink.
    The old board uses the mounting plate as a heat sink. Trapping BR1 and BR2 between the mounting plate and the board seems to have caused over-heating of these parts.
    In the new install, I mounted BR1 to the top of the board. To make this happen, I simply put an offset bend in the "+" leg so it would reach its intended mounting position. I just want to make sure that when "flipping" the bridge to the top, that I oriented the device correctly.

    Any helpful feedback and critique is welcomed.
    Thanks for looking.

    IMG_0686.JPG IMG_0689.JPG IMG_0687.JPG

    #2 6 years ago

    The heat sink you have is not adequate. The Bally design offers many multiples of heat sinking versus your idea. The bridge rectifier will quickly burn up and short out with what you have done.

    All of the above said, to answer your original question, yes, your installation will allow correct electronic operation as far as wiring is concerned.

    #3 6 years ago

    Thanks for the feedback MrBally.

    You state that "The Bally design offers many multiples of heat sinking vs. your idea."
    Can you point me towards one or even two of those ideas? I scrounged and scrounged but only found one really terrible looking remote mount modification. The bridge is removed from the board entirely and mounted remotely to the original heat sink with extended leads to accomplish this procedure.

    The reason I ask is because the parts all come from a rebuild kit purchased at Big Daddy Enterprises.
    The heat sink was included with the kit. I had no choice or control over the parts provided.

    I have access - walk-in, on the shelf - to a plethora of parts at a local electronics supply. Pretty much anything I could possibly want is readily available. I also have access to a machine shop for raw materials and bracket manufacture. If you could shoot me a pic or link to your favorite mod, I would be most grateful.
    Part numbers would be a real bonus if you can provide them.

    #4 6 years ago

    I disagree with MrBally. Bally's method of heat sinking is not well done, it traps all the heat under the board.

    You are good to go with that setup and the bridge will not burn up, at least for a long long time.

    #5 6 years ago

    While you have the board out, replace the four discreet diodes forming the logic bridge with 6amp ones and consider replacing the 1n4004 discreet diodes for the HV with 1n4007.

    #6 6 years ago

    The aftermarket heat sinks are cheap junk i make my own for bally -54 boards here the one i just did for a centaur restoration just need to add the varistor yet when they come in.

    // Error: Image 130719 not found // 031.JPG 029.JPG

    #7 6 years ago

    My 2 cents:

    The orig Bally method, although not ideal, did allow games to run 24/7 for many years.

    Fanatic: Your heat sinks do not have enough surface area and will NOT sink anywhere near the heat of the orig Bally configuration. Your rectifiers will fail early.

    Hellfire: Your heat sinks look much better suited for the job.

    #8 6 years ago

    The people making aftermarket rectifier boards use similar heat sinks.

    In fact if i am remembering correctly. Rottendog uses more discreet diodes and a single bridge rectifier top side mounted with no heat sink. Not saying that is correct or wrong, but the OP should not rework that install just for a bigger heat sink.

    #9 6 years ago

    Wow.....This discussion became more confusing than I had imagined.

    MrBally and others,
    Thanks for confirming the electrical orientation of the device. I at least know that I understand the theory behind a bridge rectifier and can connect it correctly.

    Thanks for being the only person to supply more than anecdotal evidence.
    I am curious as to how you added a heat sink to the CR1- CR4 diodes. Looks like some very nice work in your photo.

    Given all of the varying advice, I just re-oriented the bridge back where it was under the board. Seems to have lasted 30 years that way. After doing some reading, I agree that the heat sink with which I was provided is way-too-small.

    While I'm really glad I asked before popping this back into my game, I'm afraid that I've come away from this discussion with more questions than I originally had in the first place. I'm especially disappointed to have bought a "complete rebuild kit" which contains incorrect/improper parts and was shorted on other parts. I now know to trust no internet retailer.

    Lesson learned:
    Grab the schematic for your specific game and build a parts list from that document.
    And all the contradictory advice led me to look and see how to properly calculate the necessary size of a heat sink:

    Time to go borrow a non-contact, IR thermometer and do some research.

    #10 6 years ago


    If you remounted the bridge on the solder side of the board, i hope you replaced both bridges at once. Both bridges need to be physically the same size so they properly attach to the heat sink. If one bridge is thicker than the other the bridges will not sit flat and make a good thermal connection to the heat sink. Considering you had to bend the leads to make you bridge fit in the through holes i am guessing you have a poor connection to the heat sink mounted on the solder side.

    I really think you should have left it mounted on the component side the way you had it, it would have been fine for the rest of the game's life.

    #11 6 years ago

    I re-worked the board with materials supplied for the project in the kit.

    Supplied were:
    (4) 1n4007 diodes
    (4) 1n5404 diodes - (will replace with 6A4, 6A when they arrive)
    (2) 200v 35A bridge rectifier -
    various male/female connector housings and pins - all seemingly correct so far............

    Both bridges are identical in dimension and spec.
    However I do see that when tightening them to the original heat sink they flex the board in the center even with the old heat spacer pad installed. Thanks for bringing this to my attention.
    I will hit the electronics store when time allows.
    Next move is to get a length of suitable heat sink. Will remotely attach the heat sink (away from the board). Then, I will drill and tap the heat sink to support two remotely mounted rectifiers. Pin the board and install leads, connect to the remote rectifiers.

    #12 6 years ago

    Keep the bridges mounted onto the PCB. I consider it a hack when they are moved off the board. Makes servicing the PCB more difficult in the future.

    I like this heat sink and they are cheap. More challenging to find the right mounting hardware, but work much better than the black ones you originally used.


    Weight: 10.35 g

    Length x Width x Fin Height: 26 x 17 x 17 mm

    Mounting Hole Location: 7.5 mm from end
    Mounting Hole: M3 Thread, standard pitch
    Recommended Mounting Screw: M3x5

    Thermal Resistance Natural Convection: 17.5°C/W
    Thermal Resistance Forced Air Flow: 4°C/W

    #13 6 years ago

    I always do both the diodes, the fuse clips and both BR's .
    I do it the Bally way but I do it properly with clean plate and heatsink compound.
    Its possible the original design was a result of little heatsinks not being as cheap and plentiful in 1981.?
    Do it properly and they will last forever with the odd few hours use they get in private collections.

    #14 6 years ago

    ok if you have mounted the bridge rectifiers on the bottom like bally did you will need to add a additional shim or leave some extra space between the rectifier board and the new bridge becouse they are lower profile than the original cast bridges, a good way to do this is slip the bridge through the bottom of the pcb on a flat surface then set it on its legs push the leads through the topside till it touches the table under the boaard and your spacing will be right to mount the oem way then clean up the metal chassis and add silicone heatsink grease to the bridge and mount.
    The small heatsink on the top of the rectifer board i built is not on the diodes but in place i installed a 3rd bridge rectifier for the unregulated 12v that feeds the 5v regulator on the sol. control board.

    #15 6 years ago

    I suspected you might have installed a 3rd bridge - cool idea.

    And thanks everyone for the advice to fix everything while I have the board out.
    Again, I reiterate, I bought a kit which proposes to provide all of the parts necessary to de-populate the Power Module and to re-populate with superior/upgraded parts. Said another way: All old parts were desoldered from the PCB and replaced with new. For the most part, this kit did exactly what it promised.........with an exception or two.
    In a game this old I think it's wiser to rebuild entire systems rather than to wait for problems. Since problems usually spawn more problems each PCB on this game is getting an overhaul.

    I have replaced all components on the Power Module:
    Diodes, Bridge rectifiers, MOV, Resistors, New fuse clips (high current and low current), new fuses, replaced all header pins male/female and their enclosures, re-pinned all connector pins male/female and their enclosures, every removable part was removed and replaced.

    I have some new bridge rectifiers on the way since I had already mounted BR2 in the original spot by the time I took the photo and the leads were already too short by the time I asked for advice. I'll track down some heat sink material and copy your idea of top-mounting.

    My current setup should last for the next couple of days until I can sit down and correct the issue. This machine sees about an hour of use per day on average in my home.
    Since we've gone this far with the thread, I will post my "fix" here for review and critique.

    Maybe this thread can help the next guy with his rebuild.

    #16 6 years ago

    This one i did for my Elektra several years ago Its not a standard rebuild but is a better example of the 3rd bridge rectifier mounting, this was while I was running the machine on the burn in testing on some moded proto boards.

    This one has seperate amd heatsinks which worked great but i elected to revise the bridge heat sinks to 1 piece.

    The sw. Ill rectifier is the only one of the 2 that realy get warm or hot so it utilizes the extra heatsink when needed and still provides thermal protection for sol. rectifier.
    Second reason i went with the one piece heat sink was to add support and brace the PCB it loses support when the bridges are mounded on the top side of the board, the one piece braces and supports the PCB making it more rigid.


    #17 6 years ago

    OK so I was able to get by the surplus store and bought a few options in heat sinks.
    First photo shows all the options compared to the original rectifiers.

    Photo 2,3, and 4 demonstrate how the sinks will look (approximately) when mounted.

    For best heat dissipation, I'm liking the cube-shaped units.
    I understand that the other two will take some trimming and modification - drill/tap - mount rectifiers - mount to PCB

    Any opinions while I wait for the new rectifiers to arrive?
    The store has TONS of this material in stock. If I wanted to - I could remove the entire old Bally heat sink and replace with an aluminum unit complete with cooling fins. The choices were huge. There were some MONSTER sinks available and if I wanted to go completely insane with overkill, I could even mount a fan for extra air flow.

    IMG_0694.JPG IMG_0696.JPG IMG_0697.JPG IMG_0698.JPG

    #18 6 years ago

    *double post*

    #19 6 years ago

    Looks like I managed to double-post somehow. Hmmm.

    Moderators please feel free to delete either of the previous posts.
    I'm not sure what happened.

    #20 6 years ago

    the 2 square heat sinks will work good for you and prolly the easiest to insall.

    #21 6 years ago

    Thanks for the feedback. I really appreciate the guidance.
    My preference was also the two cubic-style sinks. There is obviously more surface area with all of the individual "fingers" of material.

    I can't say thanks enough.

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