• Re: Centaur/Alltek overvoltage issue

    From schukei@gmail.com@21:1/5 to mrsodapop on Sat Oct 2 15:22:11 2021
    On Friday, September 13, 2013 at 9:45:24 PM UTC-5, mrsodapop wrote:
    HI All,
    Sorry for the delay getting back to this, been away for a while.
    Here is details. From what I understand some Ballys just run a little
    high on the 12vdc circuit, this one runs at about 15.89. The Alltek MPU
    is sensitive enough to detect this and consider it "over voltage". The solution was to remove the lower left IC (U17?). I do not have the
    schematics in front of me now, but I believe this is the over voltage regulator. After removing this (U17), the system bypasses the over
    voltage circuit.
    Perhaps someone could explain why some - or this machine run high on
    the 12vdc circuit. My AC voltage going into the diodes is 14.2 -14.3vac, spec. is 14.2vac. Voltage coming out of (old/original) diodes was 15.96vdc(TP3 on rectifier pcb), I replaced the 4 diodes and TP3 is now 15.89vdc. So why is voltage high if I have factory spec. ac voltage
    going in, with proper original and replacement diodes BOTH producing a
    high DC voltage?
    Thanks for interest
    Aaron


    --
    mrsodapop

    Wanted: Photo/sticker booth.
    This USENET post sent from http://rgparchive.com
    Its actually U13 and I had the same problem in a working pin after installing a new Rectifier board. The over 5 volt LED light came on and the Allteck MPU would not boot. Removed U13 and its boots perfectly

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  • From John Robertson@21:1/5 to sch...@gmail.com on Sat Oct 2 16:27:02 2021
    On 2021/10/02 3:22 p.m., sch...@gmail.com wrote:
    On Friday, September 13, 2013 at 9:45:24 PM UTC-5, mrsodapop wrote:
    HI All,
    Sorry for the delay getting back to this, been away for a while.
    Here is details. From what I understand some Ballys just run a little
    high on the 12vdc circuit, this one runs at about 15.89. The Alltek MPU
    is sensitive enough to detect this and consider it "over voltage". The
    solution was to remove the lower left IC (U17?). I do not have the
    schematics in front of me now, but I believe this is the over voltage
    regulator. After removing this (U17), the system bypasses the over
    voltage circuit.
    Perhaps someone could explain why some - or this machine run high on
    the 12vdc circuit. My AC voltage going into the diodes is 14.2 -14.3vac,
    spec. is 14.2vac. Voltage coming out of (old/original) diodes was
    15.96vdc(TP3 on rectifier pcb), I replaced the 4 diodes and TP3 is now
    15.89vdc. So why is voltage high if I have factory spec. ac voltage
    going in, with proper original and replacement diodes BOTH producing a
    high DC voltage?
    Thanks for interest
    Aaron


    --
    mrsodapop

    Wanted: Photo/sticker booth.
    This USENET post sent from http://rgparchive.com
    Its actually U13 and I had the same problem in a working pin after installing a new Rectifier board. The over 5 volt LED light came on and the Allteck MPU would not boot. Removed U13 and its boots perfectly


    From Dave, the designer of the Alltek MPU:

    "The over voltage chip looks at the +5vdc line, not the 12vdc line.
    What people don't understand is the over voltage a lot of the times is
    the AC on the DC line because the large blue cap on the SDB is bad. So
    you get 5vdc plus as much as 10.5vac riding on the DC signal too. That
    is why the chip shuts down the board for protection. With this said it
    doesn't mean a chip doesn't go bad. It's rare but it can happen too."

    So do NOT remove the overvoltage protection circuit unless you want bad
    things to happen to your board. This will obviously void the warranty too!

    John :-#(#

    --
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