Control/Dimming - ETC Sensor CEM Classic failure mode -- repair options?

[dreamist]

Hey Gang,

I purchased a used SR12 rack for cheap (like, super cheap..), and it has a CEM Classic in it. The CEM appears to be failed -- when I power the rack, the phase lights come on and the LCD lights but never displays any data. The fan at the top of the unit comes on full speed, and that's where it sits -- never outputs anything to the LCD.

Two questions.. first -- this IS likely a failure mode, and not some odd configuration problem, yes? And second, is it worthwhile to contact ETC? Do they repair CEMs, or should I be looking on the used market for a replacement instead?

Thanks for your help.. This is my first forray into the world of Sensor racks :-)

Cheers,

Joe

[starksk]

Hi Joe,

Do all of the signal lights of all of the dimming modules also turn on when the rack is powered up with that CEM Classic? If so, the CEM classic is most likely in test mode. There is a small red switch on the circuit board of the CEM just behind the number pad that controls whether the unit is in test or normal operating mode. Toggle that switch a few times into normal (a few times because sometimes on old gear, gunk can prevent it from properly switching).

Please remember that due to NFPA 70E, the CEM Classic should only be removed or inserted when the power to the dimming rack is off (meaning the breaker that feeds the rack is off).

If toggling that switch doesn't help, please do give us a call at 800-688-4116 to arrange for a repair. We do still service these units and would be happy to assist you.

[dreamist]

Hi there Kirk! Thanks for the response!

I've only got a single dimmer module installed at the moment.. as I was just trying to get the CEM to come up and then test to make sure that all the D20s that came with the rack are good, I've got things hooked up "just barely":

This SR12 is bussed for single phase, and I have only connected Phase A (where the CEM draws its power from). I've put one D20 module in module slot 6, which is also on Phase A. I could connect Phase C with a little finaggling, but all that I've read has indicated that the CEM ought to function with only Phase A connected..

I've toggled the test switch a few times as you suggested, and can report that the signal lights on the installed D20 do indeed come on if the switch is in the TEST position, and they do not come on if they are in the NORMAL position. When in the test position, a load patched in to the D20 that is installed does indeed light at what appears to be full, and does not light when the switch is in the NORMAL position.

No matter what the position of the TEST switch, the LCD never displays any text.. the backlight comes on, but no further activity. The only light lit on the front of the CEM is the Phase A light.

In looking at the CEM, the big honking capacitor doo-dad in the center appears to have some visible damage to it's shell (it's stamped 1995, and that's probably pushing it for a dielectric like that no?)

Any other ideas before I give that service number you gave me a call?

Thanks for your help!

Joe

[starksk]

As we discussed on the phone moments ago, but, for the benefit of future forum readers, that module will need to come in for repair.

[Woodj32177]

Thanks for not leaving us hanging Kirk,
I/We appreciate it!