Wondering about wandering electrons

[itlightsup]

Hello CB

I just got my new DMXpro in the mail, and trying to learn my way around the Chamsys MagicQPC software. So far it is going well, but then I started messing around with some Martin MX4s that I thought were in perfect working order. The first two I up did exactly what they were supposed to do, with no problems from the DMXpro, the MagicQ nor the MX4s.

However.

I plugged up a third MX4 and things went awry instantly. I noticed that the DMXPro (which normal has a steady bright flashing light when active) went a little crazy, first it looked a lot dimmer than it should, then it got very sporadic in timing, then completely shut off.

I went through a step by step troubleshooting for a while and realized that nothing is wrong with then computer, the DMXpro, or the cables connecting fixtures. However, when I lamp on the 3rd MX4 there seems to be some kind of short happening.

Now I was under the impression that DMX being a one way serial signal, that any electrical malfunction on the part of a fixture would generally just be limited to that fixture, leaving the DMX chain intact, with the possibility of either just jumping over the failing fixture or at worst have that fixture become a functional terminator. I opened up the fixture, and things seem to be in order, there is no obvious short or blown circuitry; but I am about to open up one of the ones I know is working to do a compare and contrast on all of the electrics.

Has anyone had a problem like this before or could someone shed some light in my direction as to how this seemingly electric problem is smashing everything to bits?

Thanks and cheers

 

[JD]

Although DMX is one way, there is plenty of ways a fixture can blow the whole chain:

1) One of the data lines gets shorted to ground or to the other data line. This effectively loads the whole line down much like a shorted light on a circuit.
2) The fixture is producing a horrendous amount of noise, or outputting noise on the data line due to a malfunction.
3) Grounding problems, such as pin one connected to the case somewhere, is overwhelming the signal making it hard for the other fixtures to read it.

Start by running one fixture at a time and see if this fixture even works by itself.

 

[itlightsup]

Although DMX is one way, there is plenty of ways a fixture can blow the whole chain:

1) One of the data lines gets shorted to ground or to the other data line. This effectively loads the whole line down much like a shorted light on a circuit.
2) The fixture is producing a horrendous amount of noise, or outputting noise on the data line due to a malfunction.
3) Grounding problems, such as pin one connected to the case somewhere, is overwhelming the signal making it hard for the other fixtures to read it.

Start by running one fixture at a time and see if this fixture even works by itself.

Thanks for the reply!

I have definitely narrowed down the cause of the problem. It is this one particular MX4, and everything works fine until I apply power to the lamp via a Lamp on, or strobe Command.

Ballast issue?

Working through the electrics right now to try and find out if I am getting a spike off of any of the leads, but if it is pouring onto the DMX line, I think I may have a bigger problem...

I will also begin looking for a grounding issue as well, so far I haven't come across any dangly shineys but I will keep a look out.

Thanks again!

 

[mstaylor]

I vote for a bad ground. Besides loose ground wires, look for bent pins that are causing a grounding issue.

 

[DuckJordan]

Thanks for the reply!

I have definitely narrowed down the cause of the problem. It is this one particular MX4, and everything works fine until I apply power to the lamp via a Lamp on, or strobe Command.

Ballast issue?

Working through the electrics right now to try and find out if I am getting a spike off of any of the leads, but if it is pouring onto the DMX line, I think I may have a bigger problem...

I will also begin looking for a grounding issue as well, so far I haven't come across any dangly shineys but I will keep a look out.

Thanks again!

How are they powered?
Are they direct to a on/off, or is there a non-dimming dimmer connected.

Also have you just run the fixture and only that fixture not in line?