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  • Allen combination action repair

    I have been collaborating with an Allen organ user that I met on Facebook. He has an Allen 123C for which the combination action is not working. Initially, the combination action power supply was faulty, but he obtained one and had it fixed by a local tech school. He’s obtained a new, known functional combination action board DM3, but before he installed it I directed him to check the power supply to make sure it’s ok. The 5V reads just fine at 5.23 DC, but when he reads for AC volts (200 AC volts on his multimeter), he gets anywhere between 5-10v AC. I checked my known working combination action power supply, and I get 5.1 V DC on my multimeter, and 0.01V when I check the 20V AC setting. My suggestion to him is that there’s a problem with the rectifier, which would need to be repaired before he installs the new DM board. Am I missing anything here? Any other suggestions?

    -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
    -Website: https://www.exercisesincatholicmythology.com

  • #2
    If there was a rectifier or filter cap issue the 5 volts would not be correct. I suspect it's his meter. My Fluke will read AC on a DC source but my cheap throw-away meters will not. They show random AC voltage where there is none. You could have him measure again but repeat the measurement with the leads reversed to see if they match.
    Early capture supplies had a separate 5 volt module but later used the unregulated 42 volts regulated to 5 volts. Has he checked the Vp output (42 volt) for AC?
    He could check his meter's ability to read AC on a DC source by measuring other DC supplies in the organ.
    td

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    • #3
      Thanks Tucsondave. I wondered about that, he was using an old school and inexpensive multimeter. Would you recommend a better quality one, or is there another way to check for AC ripple?

      I’ll get him to check the 42V. Which power supply leads would you use to check that?

      -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
      -Website: https://www.exercisesincatholicmythology.com

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      • #4
        I would suspect a bad filter capacitor on the 5v supply rather than a problem with the meter. Replace the capacitor or preferably replace the 5v supply with something like the Mean Well RS-15-5 which is regulated and quite small, perhaps 3x2x1". The 5v is adjustable on capture supplies so set it to 5v.
        http://www.kinkennon.com

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        • Larason2
          Larason2 commented
          Editing a comment
          Thanks John, that was what I was suspecting. How many amps for the power supply? The meanwell is only 3amps, but I would suspect it needs a lot more than that to drive so many solenoids… Or is that power supply only for switching over the transistor circuits?

        • John Kinkennon
          John Kinkennon commented
          Editing a comment
          The 5v supply is only to provide 5v power to the DM board which includes a little current to each SAM's driver board for the switching MOSFETs. The power to actually drive the coils is the 48v, more or less depending on the model capture supply, that is pulsed out of the SP1 to SP4 and CP outputs. By the way, those outputs are controlled by the 4 inputs, N1 to N4 which are briefly pulled to ground. That signal could be an open collector Arduino GPIO pin.

      • #5
        Thanks John, that’s very helpful! So, to test the 48V, can you just briefly ground the corresponding N lead?

        -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
        -Website: https://www.exercisesincatholicmythology.com

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        • John Kinkennon
          John Kinkennon commented
          Editing a comment
          The high voltage on the capture supply is present on the +VP terminal. If triggering via the inputs any sustained output will cause the input breaker to trip. That's a feature by the way, not a bug. The capture supply has a circuit that ensures the SPx outputs cannot remain on and damage or overheat the SAMs coils.

        • you795a
          you795a commented
          Editing a comment
          Also, I don't know about the older capture supplies but with the newer ones, if there is no load on the output and if the piston is pressed a few times the breaker will trip as well. That is, with the trigger connected but nothing connected to the output to the SAM coils.

      • #6
        Thanks John, that's very helpful!

        -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
        -Website: https://www.exercisesincatholicmythology.com

        Comment


        • #7
          I just repaired a capture supply. Worked great. See post #24 here: Help with ADC 2010 Capture Operation - Fluttering Keys - The Organ Forum

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