Suggestions for fixing a dm-2w delay time

[petar93.mar]

hi lovely people,

as a part of the trade, I've got a faulty dm-2w. the delay times are much, much shorter than they're supposed to be. apparently, I'm not the only one with this problem. what I find strange is that the delay times go back to normal if an expression pedal is used.
Any idea on how to approach fixing this? the pedal is properly packed inside, it will be a hassle getting the pots out. btw cleaning them hasn't done a thing.
The pedal is made in taiwan, black screws.

thanks a bunch

[chromandre]

I would start by spraying the time knob with deoxit! It is possible to spray into the shaft of the pot without opening the pedal but to get a good spray you do need to disassemble it and get in the opening of the potentiometer.

[Pepe]

I doubt that it will work in a Waza Craft pedal. Don't they all have the sealed/closed potentiometer type? I cannot find a photo of the DM-2W guts, but the SD-1W definitely has the closed potentiometers.

But it could be that the potentiometer is the culprit if the expression pedal option is working properly. Maybe it was bent by strong force and just like the malfunctioning mode potentiometers that I have come across in the last years, swapping it out might turn out being helpful. The potentiometer and the expression pedal could work with digital scanning just like those mode potentiometers ...

[petar93.mar]

thanks for the replies, I have already sprayed deoxit, where it could be sprayed. But the space is really tight and the potentiometers are indeed sealed (green, blocky and mounted on a PCB). Dismantling all seems very, very time consuming tbh.
I will make some photos tonight and post them.

[petar93.mar]

Sorry for the delay (pun intended), it was a busy few days

apparently my photos are too large :/
anyways, closed potentiometers, green body, I've ordered a few, should arrive in a few days. I'll let you know about the outcome

[Pepe]

Very good! Please let us know if that is a cure for this problem.

[laurie]

It *feels* like this won't cure the problem. Without the schematic (I've looked) it is hard to tell what the relationship is between the pedal knob and expression pedal.

[petar93.mar]

Swap done, it fixed the problem. the delay time sounds about 300ms.

BUUUUUT, i was kind of cheating when I said that the EXP works. It was actually a Volume Pedal. The delay time was significantly longer and since I'd used a volume pedal, delay time just stayed on the 'longest setting'. When I tested it the first time, it was late at night and I could turn the volume though which brings me to my next point.
Delay Time is still significantly longer, but the sound is kinda weird and distorted. I calibrated a while ago a vintage Ibanez AD-9 with an oscilloscope and you could prolong delay times with an internal trim pot. When you pushed it too far though, the sound would distort and you could hear white noise around the repeats. I hope the description makes sense Volume Pedal into DM-2W sounds exactly like that!

I suppose it's high time I ordered myself an expression pedal, since I've just acquired a Supro Harmonic Trem which can also be controled via expression pedal.

[chromandre]

Cool! Yea I really like the delay times they settled on for DM-2w expression pedal feature I think you'll enjoy it too

[Pepe]

Swap done, it fixed the problem. the delay time sounds about 300ms.

Awesome! Really great to hear that it was a fruitful guess.

When you pushed it too far though, the sound would distort and you could hear white noise around the repeats. I hope the description makes sense

Yes, these are the typical artefacts of analogue bucket brigade delay. That's clock noise due to undersampling. Those delay ICs have a maximum delay time. The more you exceed this value, the more the noise increases. Actually that's what I like most in my BBD echoes.