DMX channels flicker while dimming others

[abuker]

This is my first year using DMX gear and I have RPM's DMX-USB dongle feeding the line. I am running a ColorKinetics PDS60ca with 100 rgb iColor Flex SLX pixels and two DMX4SSRs. Connected as follows:

Dongle---pds60ca---dmx4ssr---dmx4ssr---terminator
...chan 1-300. 301-304. 305-308.

Everything worked fine testing one device at a time in the shop but now that it is chained, problems have cropped up. When I dim the SSR channels, the pixels flicker random colors. I have tried changing the order of the devices on the chain and do have a 120 ohm terminator on the end.

I'm out of ideas a nd would like to have the show running on Thursday. Granted, I can still go live as-is since viewers won't know it isn't supposed to be flickering. That said, I would be grateful if anyone could provide some suggestions.

Thanks!
abuker

[RPM]

How long is your DMX wiring run to the first device?
Have you tried removing the DMX4SSR's starting from the end to see if there's a problem with one of them? What lights are you running on the DMX4SSR's?
How are you powering the dimmers? Are they all on the same power line? Have you tried running a separate extension cord to power the ColorKinetics controller?

Robert


This is my first year using DMX gear and I have RPM's DMX-USB dongle feeding the line. I am running a ColorKinetics PDS60ca with 100 rgb iColor Flex SLX pixels and two DMX4SSRs. Connected as follows:

Dongle---pds60ca---dmx4ssr---dmx4ssr---terminator
...chan 1-300. 301-304. 305-308.

Everything worked fine testing one device at a time in the shop but now that it is chained, problems have cropped up. When I dim the SSR channels, the pixels flicker random colors. I have tried changing the order of the devices on the chain and do have a 120 ohm terminator on the end.

I'm out of ideas a nd would like to have the show running on Thursday. Granted, I can still go live as-is since viewers won't know it isn't supposed to be flickering. That said, I would be grateful if anyone could provide some suggestions.

Thanks!
abuker

[DynamoBen]

The follow on question I would have is what type of cable are you using?

[abuker]

Robert, thanks for the quick response. Best guess estimate for the first run would be roughly 80-100 feet. Then I have a couple of feet between each device.

I have tested each device individually but I'll run through them again piece-by-piece to make sure I didn't miss something. The DMX4SSRs are running strings of mini-LEDs so current draw shouldn't be an issue.

The devices are powered off of a single extension cord so I'll try changing that first and see if anything changes.

I won't be able to try anything until tonight so I'll let you know what I find out after I run through the troubleshooting steps.

Thanks again!
Andrew

[abuker]

Cat5 for the cable on the entire path. ColorKinetics uses a non-standard pin-out so I convert going in and back out so that standard patch cables can be used for the rest of the connections.

[DynamoBen]

Cat5 for the cable on the entire path. ColorKinetics uses a non-standard pin-out so I convert going in and back out so that standard patch cables can be used for the rest of the connections.

Since the cable type you are using is unshielded you need to be aware of what its running next to, like an AC power source. You could be picking up noise along the way. Typically noise is canceled fairly well but its worth checking.

As a first trouble shooting step I would connect one device at a time and isolate device types. So connect your pixels one at a time until they all are connected, verify functionality as each one is added. Then disconnect all the pixels and start connecting your dmx4ssrs one at a time until they are all connected, verify functionality as each one is added. Disconnect everything and start connecting one device at a time (intermixing types) verfiy functionality as each one is added.

If each type works individually but not together be sure that all the receiving devices have common (DMX pin 1) lifted at the device, otherwise you end up with a ground loop issue which can cause flicker.

[abuker]

So far no luck but haven't had much time to troubleshoot as we got freezing rain yesterday. Hopefully it will thaw today or tomorrow and I can get back on the roof. Thanks for the input guys.

Andrew

[abuker]

Troubleshot it as best I could but gave up as nothing eliminated the flicker. I had a spare DMX-dongle, just needed to be built, so now I'm running the SSRs on a separate universe than the ColorKinetics gear. All is working well, will figure out the underlying issues in the off-season.

Andrew

[DynamoBen]

I had a spare DMX-dongle, just needed to be built, so now I'm running the SSRs on a separate universe than the ColorKinetics gear.

So when the two types are separate they work but together that don't? If so I would have to assume this is a grounding issue (ground loop).