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Modulation not working on Ibanez DMD2000

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  • Modulation not working on Ibanez DMD2000

    Hi, I purchased an Ibanez DMD2000 second-hand knowing that it had issues. Sadly for me, the main issue is that the modulation simply doesn't work:

    1) The modulation switch on the front panel does not do anything (e.g., activate its led, add modulation).
    2) None of the 8 recallable presets (may have been prior user defined) have modulation and there is no modulation footswitch jack.
    3) The modulation lfo rate led on the front panel DOES respond to changes in the modulation speed potentiometer.
    4) Everything else on the unit (e.g., delay, feedback, hold, etc) appears to work.

    I mention these things because the easiest fault would be that the modulation switch itself (or more likely the switches relay) is not working but the modulation is working. I'm at a loss as to how to test this hypothesis though given the above facts (re: presets and lack of footswitch jack), aside from testing the switching circuit on the PCB (it is very difficult to identify that circuit without additional info however).

    Unfortunately, I cannot find any information on this unit. I can find the service manual for the DM2000, but it is quite a different unit than the DMD2000 (despite the similarity in name). I also cannot find the user manual for the DMD2000. I'm wondering whether folks have any suggestions? Thanks in advance!

  • #2
    It's $25, but musicparts has the service manual.
    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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    • #3
      The only reference I can find is the Japanese low-res pdf. It does show a block diagram, though;

      http://www.maxon.co.jp/support_n/dow...d_effects.html

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      • #4
        Thank you both!

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        • #5
          Did you verify that the modulation switch itself is actually working? A DMM across the contacts should give an indication. If it's good, how easy is it to follow where the switch connects to and trace the circuit. I would also trace back from the switch LED, as it may give a clue to which area is involved. The modulation rate LED suggests that the LFO is working.

          EDIT: The unit may have a coin cell for user preset backup. If this is dead then the presets may be factory default.
          Last edited by Mick Bailey; 04-28-2022, 06:36 PM.

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          • #6
            Originally posted by Mick Bailey View Post
            Did you verify that the modulation switch itself is actually working? A DMM across the contacts should give an indication. If it's good, how easy is it to follow where the switch connects to and trace the circuit. I would also trace back from the switch LED, as it may give a clue to which area is involved. The modulation rate LED suggests that the LFO is working.

            EDIT: The unit may have a coin cell for user preset backup. If this is dead then the presets may be factory default.
            Hi, sorry for how slow I am, but I finally was able to test the switch and it works! It is not easy for me to follow the switch connects to trace the circuit, unfortunately... However, I think this is likely due to my lack of skills, so I linked a few pictures of the switch/led front panel lcd (bc my upload limit is like half a picture):

            1. https://ibb.co/8062gQX

            2. https://ibb.co/RPczbwM

            The unit does have a soldered-in coin cell for user preset backup. I tried measuring its voltage by setting my multimeter to 200m or 2000m and pressing one probe to one side and the other to the other of the battery, but I'm not sure I trust my findings because each time I touched the probes to the battery the number became smaller and smaller...

            Thanks for hanging in there with me!

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            • #7
              Originally posted by focusbob View Post
              ......The unit does have a soldered-in coin cell for user preset backup. I tried measuring its voltage by setting my multimeter to 200m or 2000m and pressing one probe to one side and the other to the other of the battery, but I'm not sure I trust my findings because each time I touched the probes to the battery the number became smaller and smaller.........
              You set your meter to 200m or 2000m. 'm' what? Is that millivolts, meg ohms, milliamps, what were you measuring? Typically a coin cell is 3VDC, so your meter should be set to read 3 or more volts DC.
              "Yeah, well, you know, that's just, like, your opinion, man."

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