Control/Dimming Problems with DMX -> ECMUX?

[Abscynth]

Hi there! I work in a live theatre in Grande Prairie Alberta (Canada eh'!) and am having a serious problem with my lighting setup during performances..

Its kind of a long story and any hints, ideas, or suggestions would be VERY appreciated!

Last week we had an electrician working on a timer box in my control room, I suspect she caused a power surge in the room. I went in the next evening to do a show and got nothing off the Board (I use an ETC Express 125) I traced the original problem to the 1st DMX port on the board, I was able to get lights to come up by switching to the 2nd port and telling port 2 to start at dimmer 1.
Problem solved? No..
My lights flickered throughout the evenings performance..So I rented a board - Hooked it up, Lights still flickered.
I use 4 dimmers, 2 CD-80s, and 2 VERY OLD EC Playmates, With a DMX --> ECMUX converter box. When I unplug the converter box, and just run with my CD-80s, my lights are fine, As soon as I wire the box back in...Lights starting flickering randomly.
Yesterday I was able to do an entire show with no flickers, and this evenings performance went almost an hour before any problems arose..It flickered 5 or 6 times..Then stopped for about a half hour..Now its back worse than ever. I have a STRONG suspicion that its the converter box..But since its a 1,300 dollar box I'm hesitant to switch it out..

Has anyone else ever had similar problems? Ideas? Thanks very much in advance for any information you can provide!

Ian Bowen.

 

[Tex]

Random flickering sounds like a DMX short somewhere. Check all your cables and the ports on your converter box. I'd be willing to bet there's a short somewhere...

 

[dramatech]

It sounds as though, the transceiver IC for port one of your express is dead. It would also indicate that you probably had some sort of spike go down your DMX line. The voltage spike probably did some harm to the transceiver IC in the MUX convertor as well. First check all of your cables, and make sure that none of the connectors shells are wired to pin one. You can do this with a continuity checker or ohm meter. Unplug the cables from all devices and then using a checker, see if the shell of the connector is connected to pin one. Check both ends. If you find a connection, open the connector cut the connection to the shell. As the shell of the connector sees earth ground, if your electrician touched hot to ground even for a second, it could fry the transceiver ICs on the devices connected to the errant cables.
Depending on your familiarity with electronics and circuit boards, The transceiver chips are pretty simple to replace. If not familiar, then you need to send the board and mux convertor for repair or find a competent technician. The IC in the express is a 75176 and it probably is the same in the mux convertor, but no guarantee. In the express, it is socketed, so it is an easy replacement. If you don't use the RFU on your express, there are two ICs in the board that can be swapped to the port one socket. If you feel competent to work on it or have somebody who is, you can contact me and I can talk you through it. As for the Mux convertor, that would depend on how easy it is to get to to the circuit board and if the IC is in fact a 75176 and if it is socketed. Good luck!!

[email protected]

 

[Abscynth]

Thanks for the ideas guys! Everything seems to be checking out continuity wise in both the box, and the DMX lines running to the booth. Unfortunately the problem seems to be very intermittent, Last night the show ran for almost an hour before any problems arose, Then stopped, Then resumed flickering after about 30 minutes.

I was able to "compress" my show down to one dimmer and eliminate the need for the 2 Playmates, and one of the CD-80's, Everything appears to be fine now but the next show we have coming up probably won't fit on one dimmer!

I'll let ya'll know what happens when I get my "DMX Ultimate Converter" (Which according to Production Lighting is the only box currently on the market capable of switching DMX -> ECMUX)

Hooray for equipment that is older than I am!

**Edit, Show went off tonight without a hitch (I wired everything into my 24 channel CD-80, patched everything to make it work with the show...and prayed for the best!**