djgeorgef

I’m interested in a enttec usb pro to replace my trusty one that I had for many years but sadly gave up recently. Please message me and hopefully we can come to a deal. Thank you 

Thank you all, it’s been a great help. 

7 hours ago, Brian said:

A few comments...

Leads - the cable shield is connected to pin 1 and pin 1 only. It is never, ever, to be connected to the connector body. Ever.

DMX Receivers - there are 3 possible circuit configurations for a DMX receiver.

1. Isolated. Pin 1 is connected to the input circuit's signal common. It is not connected to the chassis or any other earthed point.
2. Non-Isolated. Pin 1 is connected to the input circuit's signal common which is then connected to the chassis and incoming earth via a resistor, typically 100R. The resistor is there to limit the current flowing in the cable shield in the event of a system fault.
3. Grounded. Pin 1 is connected to the input circuit's signal common, the chassis and the incoming earth.

Isolated is the preferred configuration, the other suck from a systems engineering stance. If using Grounded receivers it is highly recommended to have a fully isolated transmitter.

Thank you that’s very informative, we appear to have scenario 3 in our dimmer! By a fully isolated transmitter, would a DMX splitter with optical isolation suffice in your opinion. 

6 hours ago, DrV said:

I believe the enttec pro dongle is already optically isolated (could have a look in mine tomorrow) but using an optically isolated splitter would certainly minimise your risks.

Yes it is,  apparently it sacrifices itself to save the desk/computer in the event of a voltage spike! It looks as though Enttec will be able to refurbish it which is good 

26 minutes ago, Jivemaster said:

Are you working with one mains supply or several? If power is coming from several places than it's possible that the power ground is at a different potential on each supply and when these are tied together with a XLR lead bad things may happen to digital things (especially with a fault that tripped a breaker somewhere). 

Perhaps having a DMX isolated splitter between your PC/dongle and everything else and feeding some things from each output will help. 

Making sure that the digital ground is always separate from the power ground/CPC would be my first choice. 

Thank you, I found this really useful. At least 2 of the dimmer units are on different ring mains. I like the idea of the splitter and then run a DMX cable to each unit. At least if one goes down the rest should stay active. 👍🏻

Thanks all for clarifying the cables so far, I’ve re-soldered the XLRs to keep pin 1 separate from the chassis. Had a quick look and am able to separate the mains earth and DMX ground quite easily in the units. Also
 

I'm paranoid it’s going to happen again, would optical isolators help to reduce this and would I need one on the input and output of each unit or is that overkill. Also do you think it’ll be enough to keep the grounds and earths separate. 

 

Apologies, just to explain a little more, this is a setup over Xmas that I’ve been volunteered for for a local non profit organisation. I’m an electrician but when it comes to DMX I’m a plug and play kind of person with a basic understanding until it goes pop, and would like a set up we can just roll out and plug in every year. 
 

thanks again, really appreciate all the help

1 hour ago, sandall said:

Think he means connector shields, not cable screens (common problem with Chinese cables)

Hi, thanks for the replies. So there are 2 cores and an overall braided shield. Pin 1 has one the overall braid/shield connected but The the shield is also soldered to the connector “earth” terminal in the xlr that goes to the xlr connector. 

Hi all, I’m just after some clarification on an issue I’m having with some DMX rgb dimmer packs please. It’s a very basic setup: computer > DMX dongle (enttec usb pro) > 3 x rgb dimmer units (24vdc) 5m apart running some rgb floodlights. 

 

so the story goes…..all working lovely until a random rcd went somewhere else in the venue unrelated to the lighting setup, but on the same distro board (probably a toaster or something!!)! This resulted in 1 of the dimmer packs failing and also the enttec DMX dongle failing. Obviously very annoying!!

After looking into it, pin 1 on the DMX dimmer pack is also connected to the metal chassis inside the rgb units and hence earthed! So my theory is a spike on the earth found it’s way through to the ground on the DMX and blew the comms chip in unit and dongle? So my questions are:

1. Does this sound plausible? No faults found on any of the 24v circuits.

2. I’m assuming that the mains earth should be open circuit from the DMX ground on pin 1. Hence a badly designed/made rgb unit

3. I’ve also noticed the DMX cables (qtx brand) have the shields link to pin 1 in the xlr connectors. I’ve read that the shields should be separated from pin 1 also but quite contradicting depend on various posts

 

I’ve obvious got a niggly one here, sorry there’s a lot there but trying to future/idiot proof this so it doesn't happen again! I’m also looking into optical isolators also. Any advice would be greatfully received. Thank you in advance. 

I’m looking to purchase dumb RGB dimmer controllers/boards, DMX controlled and approx 4A per channel. Preferably not cheap amazon or Ali boards. 24+ channels and 24vDC output. Thanks in advance

Hi, I’m in the market for some Co2 cannons/solenoids, preferably mains voltage, DMX not essential. 2 units required ideally, thanks in advance