Remote (phisically!) control

Testing/Troubleshooting
1

Hi everyone, I read a lot of topics regarding jitter and signal interference between pots, but none seem to solve my problem.

I have the following hardware on my MB64:

1x core

2x din

I didn’t stuff the hc165 on the DIN because I’m experiencing problem with pots and I would like to solve that issue first. They are connected on j5 of the core so I have 8 pots w/o multiplexers. 6 are knobs, 2 are sliders. The pots are connected near the core and they work perfectly, but I experience a lot of interference when I connect the 2 sliders. It is quite normal since the faders are connected via ribbon cable to j5 pins through a subD 25 pole port to another panel (about 2 metres of cable) and the Vss Vdd and wiper cable (4 in total) are very near. I have random data ONLY from the 2 faders, when I move the knobs or when I touch nothing.

Is there a solution to this? note that the faders cables are very near to the display cables too, I tried to stuff a cap (different values from 330 pF to 1 mF) between Vss and Vdd, but I noticed only a small reduction of signal noise. Is the length of the cable the problem? Thanks in advance!

2

I forgot: I donwloaded Thorsten’s jitter_monitor app and I see jitter values from 01 to 06, worst case 08. I don’t pretend to eliminate jittering, but at least eliminate the random data from the 2 faders.

3

Well, it happens that sometimes the two faders send random values of the controllers they are assigned to. And every time I move them or move the knobs the MB sends out those damned random values from the faders… I’m in a deadlock, it seems like the supply pin of the faders are floating, is this because of the length of the cables? I can’t use shielded cables since they’re too thick for my purpose.. Any idea?

4

Hi,

It could help to supply the faders directly from J2, to add 100 nF caps between the +5V/Ground pins of each fader, and in addition a 100nF cap between the wiper pin and ground. But in general, without shielded cables you won’t have much luck - over such a distance they are really required. Also the sub-d port you are using is not the best choice for analog signals.

Best Regards, Thorsten.

5

I had tried this yet, in fact improvements were very slight. TK, do you think that mantaining the sub D port but using shielded cable I can fix the problem? I should use shielded cables for every pin of faders (Vss Vdd and wiper right?) and has anyone got an hint on good shielded cables without exagerated dimensions? thanks

6

I think that such a cable should be ok:

it’s cheap and especially thin.

You can use one wire for the wiper, another for +5V, and the shield for ground

> do you think that mantaining the sub D port but using shielded cable I can fix the problem?

not when you want to achieve lowest jitter, but so long your fader only send 7bit values, it could work

Best Regards, Thorsten.

7

Thank you Thorsten :wink:

I found a way out to customize my MB64 design, your help is truly valuable.

As soon as I complete that damned case I’ll post photos on forums! :smiley:

8

In my new design, I was wondering if I’ll encounter problem with the following setup:

I built a pedalboard with 60 keys, installed in it 2 DINx4 and I’d like to connect J1 of the first DINx4 on a  9 poles subD port. 2 m away I have another panel stuffed with core, LCD with the 4 navigation buttons near and 8 pots and another subD 9pole port.

I would like to connect the 4 buttons to the female subD on the panel with the pots  and the remaining 5 poles to J9 of core, so that core J9 and DIN J1 are connected this way, while the 4 buttons are connected to the serial pins of Dinx4. Do you think I’ll have jitter problems? Since those are not analog signal I assume that I’ll avoid self-playing keys right? The cables which are near and 2 m long are the connections between core J9 and din J1 + serial pin to buttons. Thanks!