Community Static IME issue

This is a continuation of this thread.

a forum member (I don’t know who because I lost my p.m.'s in the old forum) Told me they where having the same problem as was described in the other thread and that it was because of static stored in the IME’s. This seems like a very logical explanation to this, but we would still like to be able to use 4 IME’s as it is crucial to our autonomous .

To help us with your issue, what are the lights doing on the Encoders? The patterns are described at the bottom of http://www.vexrobotics.com/encoder-modules.html  . Click on the LED Patterns tab.

2 seem to work and show a slow flashing green light, but as soon as more are plugged in, the extra 1 or 2 turn solid yellow and give no feedback to the cortex while the first 2 in the chain are still green.
We only have 1 cable between the cortex and the first IME, but 2 between every IME.

EDIT: From testing just now, we have 2 IME’s (1 wire to the first and 4 to the second) and we are still Constantly cutting out. When we unplug them, everything works perfectly.

Anyone found a solution or having similar problems. It just seems to be getting worse. Any way to ground the static?

Read my comments on Static here
https://vexforum.com/t/esd-my-thoughts/23332/1

Static is not “stored” in the IMEs. The IME/cortex can be affected by static build up on the robot.

It sound like either, too many cables or an bad IME. Have you tried to identify which one of the four may be bad, ie. remove one of the two that don’t work?

Cool! That’s a lot of good information. I didn’t know that the amount of cables could effect the IME’s. When we have all 4 IME’s in the circuit, we have 6 or 7 total wires. It seems that when just the right 2 IME’s are plugged in, then those two are both green and nothing cuts out, but the left side rarely works recently. I’m going to do some more individual tests on it tomorrow and probably try replacing some.

Our robot is on omni wheels and we work on a plastic table. The robot used to constantly shock us while we were working on it. It got really annoying and painful after a while so we’ve resorted to taking alligator clips and connecting those to a shaft which fits well in the walls ground plug. While very unsafe it dosen’t shock us anymore which, I think, means the robot was building a positive charge and it is dissipated to ground now. I wonder if we used bearings throughout the drive and plastic washers on the motors we could localize the charge?

Eeek! Can’t you find something less dangerous to ground to? Like maybe a water pipe? or a metal support structure in the building?

Even then I suggest you look at how wrist grounding straps are designed for people who work with sensitive electronics. They put something like a 1 MegaOhm resistor in series on the line so that static can be bled away but if the end of the wire were to happen to contact wall power, the resistor would greatly limit current that could flow into the person’s body. In fact, you might even consider putting such a resistor on each end of that wire. But what you’re doing now sounds scary. :-0