(Topic ID: 294382)

KAHR WPC MPU Power Fix Circuit add-on daughterboard

By zhu808

4 months ago


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  • 78 posts
  • 21 Pinsiders participating
  • Latest reply 4 months ago by Pin_Guy
  • Topic is favorited by 6 Pinsiders

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    There are 78 posts in this topic. You are on page 2 of 2.
    #51 4 months ago
    Quoted from KenLayton:

    I think people are forgetting that the Kahr board is sold in two versions: a "basic" no frills version and a "deluxe" version. I have had trouble with the deluxe version, but never any troubles with the basic version.

    Mine is the basic, just FYI.

    #52 4 months ago
    Quoted from DumbAss:

    My gripe is with statements saying that all the mods added to the system are drawing the "12V" supply low.

    The first thing I said in this thread is that he shouldn't be asking about resets without measuring some voltages, as others said previously.

    Quoted from DumbAss:

    Those mods are connected to +12VU.

    Safe to assume that for the color dmd, because it's wired that way, but not all the other mods. I've seen plenty of mods powered by a wire soldered to a test point on the driver board.

    I honestly didn't want to know what was plugged in where. He seemed to be pointing a finger at the daughter board, but left out a huge amount of details about the game. He's new here. Now he knows.

    #53 4 months ago
    Quoted from phishrace:

    He seemed to be pointing a finger at the daughter board

    Removing it resulted in my machine functioning properly, so yeah, I think blaming that board was reasonable.

    #54 4 months ago

    I would say the problem was excessive loading of 12V caused by the add-on mods. The daughterboard designer of course can't predict how much extra load there is in addition to the board itself.

    #55 4 months ago
    Quoted from Tuukka:

    I would say the problem was excessive loading of 12V caused by the add-on mods.

    I don’t think there is enough information to make this determination yet. Back in post #26 this was mentioned:

    Quoted from phishrace:Many upgrades including ColorDMD, magic wands, spinning hat, working tiger saw, trunk locks and more.'
    https://pinside.com/pinball/market/classifieds/archive/113284

    But zhu808 hasn’t said exactly what was connected where and probably doesn’t yet have the technical know how to determine the answer.

    It’s an interesting problem. I learned some things from this thread. Good to hear different opinions on what might be happening. Without being able to look at and test the machine there is some amount of guesswork involved.

    To help zhu808 determine why Theatre of Magic was having problems until the Kahr board was removed can we come up with a methodical process that could be followed by someone new to electronics troubleshooting? Maybe start with a list of every mod connected, what voltage the mod used, and where it was connected? Then measure , maybe monitor them over time? That’s a big ask for a new tech.

    #56 4 months ago
    Quoted from zhu808:

    Removing it resulted in my machine functioning properly, so yeah, I think blaming that board was reasonable.

    You could stick it on another machine, see if it screws it up too. Then we'd know for sure.

    #57 4 months ago
    Quoted from Leeb18509:

    You could stick it on another machine, see if it screws it up too. Then we'd know for sure.

    Unfortunately, this isn't an option for me, otherwise I would have tried it based previous advice.

    #58 4 months ago

    If you haven't already done this, I'd put the Kahr board back in and see if the game starts resetting again. It's possible that a connector wasn't making good contact and the simple act of exercising it made it better.

    #59 4 months ago
    Quoted from zhu808:

    Cool - I would love to do this.
    Where do I start?

    Here is what I did for my BSD and CFTBL.

    https://pinside.com/pinball/forum/topic/hologram-mod-for-creature-from-pinballsp-is-under-development/page/23#post-5119156

    Focus on step 3 and 4 for to get the power supply hooked up to the game and supplied power from the wall outlet to the power supply you are introducing.

    Like others have said, doing this will supply constant power to whatever extras (ColorDMD for example) you plug into the power supply. To get around that, look at steps 1 and 2 (introduction of power strips with remote "on and off" feature).

    Let me know if you need any further help walking through the process.

    #60 4 months ago
    Quoted from pins4u:

    It's the low 5V on the MPU that causes resets. It's not really connected to the 12V - the 12V 'could' go down to 9V and still the MPU probably wouldn't reset. YES, other things will get upset but don't confuse what the two different voltages are for.

    I don't think you fully understood this thread, all the KHAR board does is uses the 12V going to the MPU to produce a new 5V source to power CPU; if the 12V is degraded or overloaded then the 5V its providing will assuredly be affected.

    #61 4 months ago
    Quoted from YeOldPinPlayer:

    Resets from low 5v is a common issue on WPC games. It’s a design weakness.

    If this is true, why is it that neither my TZ nor STTNG have any power related issues despite both having all original WPC boards that are 28+ years old?

    #62 4 months ago
    Quoted from Tuukka:

    I would say the problem was excessive loading of 12V caused by the add-on mods. The daughterboard designer of course can't predict how much extra load there is in addition to the board itself.

    I feel the whole mod theory is misleading/wrong information and would like to put this to bed; aside from the KHAR board, can anyone tell me of a single mod for this game that is designed to connect to the regulated 12V circuit? I can think of none.

    #63 4 months ago
    Quoted from Jvspin:

    If you haven't already done this, I'd put the Kahr board back in and see if the game starts resetting again. It's possible that a connector wasn't making good contact and the simple act of exercising it made it better.

    The female connector on the daughter board latches onto the CPU board like vice grips. You have to support the back of the CPU board to keep it from flexing too much when installing the board. That tight connection no doubt cleans the males pins on the CPU board when it's first installed. You could have a problem with the factory IDC connector that connects to the male pins on the board, but I don't suspect that was his problem.

    Some very simple voltage readings would tell us most everything we need to know, but he seems to not want to know any more as his game is working again. I've put the daughter board in lots of customer's games and have never had a call back. Usually don't need to rebuild connector J-210. Rock solid product. If the original poster lived near me, I'd ask him to give me his 'broken' board. For research purposes, obviously.

    #64 4 months ago
    Quoted from Pin_Guy:

    I feel the whole mod theory is misleading/wrong information and would like to put this to bed; aside from the KHAR board, can anyone tell me of a single mod for this game that is designed to connect to the regulated 12V circuit? I can think of none.

    There's no point in going any further without more input from the original poster. I'm curious if the tiger saw motor and hat motor are running off unregulated 12V. Seems like they might not last long. Guess we'll never know.

    The real lesson to be learned here is don't move to Hawaii and buy pimped out old pinball machines if you don't have any technical skills.

    #65 4 months ago
    Quoted from phishrace:

    I'm curious if the tiger saw motor and hat motor are running off unregulated 12V. Seems like they might not last long. Guess we'll never know.

    sure we would, nearly all 12V motors in every WPC game runs off unregulated 12V and they are low failure parts.

    #66 4 months ago
    Quoted from Pin_Guy:

    sure we would, nearly all 12V motors in every WPC game runs off unregulated 12V and they are low failure parts.

    Those all go through a motor board before any power goes to the motor. I've heard of and have probably seen the tiger saw blade mod. It's been around awhile. The first issue he mentioned was that mod. Seems like I've heard of the hat one too, but I've never installed either.

    If only we could get our hands (and meters) on this game. I suspect we'll hear more about it in the future.

    #67 4 months ago

    The big user of 12V Reg of all the MODs is the color DMD.

    #68 4 months ago
    Quoted from phishrace:

    The real lesson to be learned here is don't move to Hawaii and buy pimped out old pinball machines if you don't have any technical skills.

    LOL. I moved to Hawaii 11 years ago. I shipped this game from California recently. I bought my first pinball machine back in December of 2020, and now I have three. Sorry - I'm not going to become an expert technician overnight, especially when I work 4 different jobs. I'll check the voltage when I get another multimeter. Until then, keep your pants on.

    #69 4 months ago
    Quoted from NPO:

    Here is what I did for my BSD and CFTBL.

    Awesome. I'll take a look at it. Thanks for your help!

    #70 4 months ago
    Quoted from Jvspin:

    If you haven't already done this, I'd put the Kahr board back in and see if the game starts resetting again. It's possible that a connector wasn't making good contact and the simple act of exercising it made it better.

    I've had two Kahr boards in there, and they both caused reset issues and then some. There's no way I'm putting one back in, especially now that the machine is working. What I am going to do though is get these mods running off of an external power supply.

    #71 4 months ago
    Quoted from zhu808:

    I've had two Kahr boards in there, and they both caused reset issues and then some. There's no way I'm putting one back in, especially now that the machine is working. What I am going to do though is get these mods running off of an external power supply.

    Were they the deluxe model or the basic model?

    #72 4 months ago
    Quoted from KenLayton:

    Were they the deluxe model or the basic model?

    Both basic.

    #73 4 months ago
    Quoted from minnesota13:

    The big user of 12V Reg of all the MODs is the color DMD.

    OMG ... again NO! The color DMD is NOT powered off regulated 12V, it uses 12V unregulated voltage.

    I honestly want to apologies to the OP for so much incorrect information in this thread while you are trying to learn how to fix your machine.

    From Color DMD installation manual:
    pasted_image (resized).png

    From TOM Manual page 3-27:
    pasted_image (resized).png

    From WPC89 schematics:
    pasted_image (resized).png

    The entire unregulated +12V circuit from the transformer to the Power board output:
    pasted_image (resized).png

    It honestly is that simple, you rectify the incoming AC power to create DC, you filter it remove low frequency noise, and send it on its way. Any circuit boards under the playfield that use this voltage contain another filter cap at the input to clean up any noise induced on the power line along the way.

    #74 4 months ago
    Quoted from phishrace:

    Those all go through a motor board before any power goes to the motor.

    Yes they do; I'm not going to bother discussing what the motor board does ... maybe DumbAss would.

    #75 4 months ago
    Quoted from Pin_Guy:

    OMG ... again NO! The color DMD is NOT powered off regulated 12V, it uses 12V unregulated voltage.

    Thank you for your kind correction. I had regulated power on my mind and know that the DMD is powered by the unregulated 12VDC circuit. That does not change the fact that the color DMD draws on the 12V unregulated circuit and +5 and is the largest draw on machine power of all of the MODs.

    #76 4 months ago
    Quoted from minnesota13:

    That does not change the fact that the color DMD draws on the 12V unregulated circuit and +5 and is the largest draw on machine power of all of the MODs.

    It wasn't so kind as I tend to only state facts and not to sugar coat anything.

    I never said the ColorDMD wasn't a heavy load ... I asked folks to list Mods that use Regulated 12V power because I already know there are none and want people to attempt to prove me wrong...most don't respond back as the facts speak for themselves. I do want to correct you on one point though, the Color DMD does not put any load on the games +5 Volts as this pin is unused by the ColorDMD, the Color DMDs on board controller produces its own regulated +5V operating voltage power from the unregulated +12VU source.

    Other thoughts: I actually prefer the ColorDMD LED version in these older machines and they not only look better IMO but also draw about 1/10 the power of the ColorDMD LCD version.

    #77 4 months ago
    Quoted from Pin_Guy:

    prefer the ColorDMD LED version in these older machines and they not only look better IMO but also draw about 1/10 the power of the ColorDMD LCD version.

    Not a factor in reset issues though, right? Since it’s not using the already taxed 5v.

    #78 4 months ago
    Quoted from YeOldPinPlayer:

    Not a factor in reset issues though, right? Since it’s not using the already taxed 5v.

    No, its not a factor at all

    There are 78 posts in this topic. You are on page 2 of 2.

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