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Re: Dead MP4 need help

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  • iscrites
    Thanx for the reply. I took the precaution of unpluging the 5 left connectors. Though when I did it I have the 4 VCO leds that lit. I guess the power comes
    Message 1 of 6 , Oct 23, 2012
      Thanx for the reply.

      I took the precaution of unpluging the 5 left connectors.
      Though when I did it I have the 4 VCO leds that lit. I guess the power comes from the KLM357 board but how does this one get it ?
      There is a red wire connecting + side of KLM376 C14 to input of KLM327, so I guess it come from that.

      To answer your question:
      - I got -37v between pin 1 and 4 of the M3250L
      Actually I have a fried resistor on R15 so I can't read pin 7 but I read 37v on + side of C14, so it should be the same on pin 7 wasn't it for the fried resistor.
      I fried that resistor (I guess) by reading C13 yesterday and I guess I short circuit the C13, there was a explosion and the R15 was fried. Well maybe it was fried before the explosion but I didn't notice it.
      I did not mention this because I guess it should still get the -15v and +5V even without it, no ? (I just don't have a 130 resistor on hand)
      Another thing is I don't always get the same readings. Sometime it's more 35v and sometimes more 37v.

      I thought of changing the power suplly completely (and using a 230v one) but I lack some knowledge:

      - what current rating does it need to be ?
      - how should I feed the 36v to the KLM327 ?
      - how do I make the 5 connectors (by cannibalizing the KLM376) ?

      Can you point me with an appropriate power supply ? (on ebay, mouser, conrad etc)

      Thanx a lot
    • Florian Anwander
      Hello ... I think you will need 150mA for each section, but I am not sure. The specification in the servicemanual does not name it. ... argh! I forgot about
      Message 2 of 6 , Oct 23, 2012
        Hello

        > I thought of changing the power suplly completely (and using a 230v one) but I lack some knowledge:
        >
        > - what current rating does it need to be ?
        I think you will need 150mA for each section, but I am not sure. The
        specification in the servicemanual does not name it.

        > - how should I feed the 36v to the KLM327 ?
        argh! I forgot about these. It will make it complicated.


        > - how do I make the 5 connectors (by cannibalizing the KLM376) ?
        Yes

        > Can you point me with an appropriate power supply ? (on ebay, mouser, conrad etc)
        If my specifications are right
        http://de.farnell.com/tracopower/tmp-15515/wandler-ac-dc-5v-15v-15w-module/dp/1672148


        Maybe you should look out for a used Polysix PSU. They might be identical.


        Florian

        --
        http://fa.utfs.org/
      • iscrites
        So I guess without the 36v for the KLM327 it is not possible to use another power supply. Also forgot to ask earlier but if you use another power supply, how
        Message 3 of 6 , Oct 23, 2012
          So I guess without the 36v for the KLM327 it is not possible to use another power supply.

          Also forgot to ask earlier but if you use another power supply, how can you fine tune the voltage to make it meet the specifications in the service manual ?
        • iscrites
          Some news: After several attempts of reviving the power supply I bought a 15v, -15v and 5v power supply and installed it today. Good news is that it works and
          Message 4 of 6 , Nov 14, 2012
            Some news:
            After several attempts of reviving the power supply I bought a 15v, -15v and 5v power supply and installed it today.

            Good news is that it works and almost every aspect of the monopoly is working.
            The only problem I have now is that if the KLM398 board is connected, the sound of the osc is a weak distorded high pitched sound and I can not pitch the sound (either with the keyboard or arp or transpose).

            If I disconnect the board, I have 4 perfectly sounding osc which I can change waveform, but still no pitch control.

            I thought the 398 was the culprit but I changed the 2x TL072 and it did not change anything.

            I guess the problem is with voltage control of the OSC. Where should I investigate ?
            i checked the voltage on the connectors of every board and I read the 15v, 15v and 5v.
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