Modulation not working on Ibanez DMD2000

[focusbob]

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!

[g1]

It's $25, but musicparts has the service manual.

[Mick Bailey]

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

[focusbob]

Thank you both!

[Mick Bailey]

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.

[focusbob]

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!

[The Dude]

......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.

[focusbob]

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.

Thanks, and sorry for the confusion. My measurements were in mV (milliVolts). My meter has 20V, 200mV, and 2000mV settings (and others). Point being, readings were well below 3V, with the value decreasing each time I measured it (which I don't fully understand). Either the battery is dead or I am incompetent with the meter (both are possible!), however, either way the battery being dead or not wouldn't effect my lack of modulation woes. I was just wondering whether the current presets on the machine were potentially non-factory stock (alive battery) or more likely factory default (dead battery), as per a previous question.

[focusbob]

Apparently, the modulation does not work (and the switch does nothing) above 1023 ms delay time...