Strand CD80 AE not responding to DMX

Greetings,

I help out some NYC schools with their sound & lighting equipment and have run into a problem that's stumping me.

Strand CD80 AE dimmer rack, installed c. 1995, 18 dual-circuit 2.4K dimmers, probably hasn't been used in 5+ years; students trashed the NSI/Leviton MC 24/48 console (don't know if it works); a dozen Altman StarPars, a few ellipsoidals (pbly 360Qs), a smattering of PAR cans - no idea what lamps are burned out or intact.

The issue is - No light fixtures respond to fader changes issued from a DMX control console even though the rack indicates INPUT A is present.


Troubleshooting steps taken:
  • Connected 2 different DMX consoles (Elation Stage Setter 24 & Elation SDC12) to a DMX input wall jack and INPUT A light lit on Input Processor module
    • No lights responded to fader controls
  • Removed the F1 fuse from the power module
    • The rack powered off
  • Removed the F2 fuse from the power module
  • Removed the F3 fuse from the power module
    • Another set of lights came on at full intensity

From what I've gleaned from the CD80 AE manual, the above is largely expected behavior - except for not responding to the DMX console commands. Most of the tests were performed with the Program switch on and off.

Any advice for next troubleshooting steps would be appreciated. I've tried calling and emailing Strand support personnel w/o any response, so far.

Thanks,
Keith
 

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It should not be in program mode. Turn the program switch off, then momentarily power down the rack from its main breaker. Pulling control fuses does not bring all rails up together.

You need to have at least one, known working light, otherwise, how do you know the rack isn't working? The only other way to know is to turn all control to 0, including both DMX and architectural controls. With no control for a light to be on, the rack will go to sleep in a few minutes and the fans will shut off. Then, raise a DMX channel, and the fans should start up.

I'd like to think that Strand would support a 25 year old AE but I seriously doubt it. They dumped spare parts quite a while ago. Lite-Trol Services and Emlight Design are the best resources for old dimming system support. There is at least one, common failure in AEs that those guys will know about.
 
Having called strand in the past for advice on a CD80 AE, it's pretty hit or miss, and no, they don't particularly have parts for them left...

You can likely get the contact information for the installer somewhere on the rack, if not, strand support should be able to point you to some numbers for installers in your area.

In our case, we were able to get the installers information, and they still had the original drawings and specifications for our installation from 1993.
 
If your installation is anything like mine, there's a good chance that between the console and the dimmer, there's some decrepit old strand architectural panel that interrupts the signal between the console and dimmer. If someone bumps the wrong button on it, everything the console is trying to send will be ignored and not passed on to the dimmer.

In our case, the primary function of it was to interface a wall mounted key switch to override several circuits of the house lighting (which is run off the dimmer in our case) to a minimum level. I probably have a photo of the darn thing somewhere uploaded on controlbooth...
 
And the answer is...

I'm finally back in this school again after two years - and got the dimmers to respond to DMX!!!

I did multiple things (of course), but feel fairly certain of what "fixed" the situation.

1 - I turned off the "Program" switch
2 - Because I couldn't find any custodian who knew how to completely power down the rack, I removed the 1st fuse on the Power Supply Module, which powered down the Command Module, and then I exercised the Input Processor Module by removing/reinserting it several times. I'm sure I removed a couple decades worth of corrosion doing this move...
3 - When I restored the 1st fuse, I saw normal green lights on the PSM and IPM.
4 - The Input A and Input B jacks at the top of the rack don't seem to be connected - when I plugged in there I never saw the corresponding light on the IPM respond - it still blinked SELECT.
5 - When I plugged into one of the DMX IN wall jacks the IPM showed that it was receiving DMX signal on input A
6 - Light fixtures responded to DMX signals!
7 - Joy and hilarity ensued.

Thank you, everyone, for your helpful suggestions above. They really helped me understand the system (along with the manual, of course) and where I should concentrate my attention.

Another ControlBooth mystery successfully SOLVED!
 

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