Sensor Overtemp Operation

Sensor dimmer overtemp error messages are generated when a dimmer's internal sensors indicate that it is running too hot.  This message is then sent to the CEM, and "OVERTEMP XXX" is displayed.  On the MPE, the beacon will flash, and you can run tests to see what the error is.

This issue is most often caused by one or more dimmer modules, rather than the CEM Classic, CEM+, or CEM3 itself. The circuitry receives overtemp signals from the dimmer modules and is not designed to generate an overtemp signal. It is far more likely that the CEM will not detect an overtemp if the hardware on the CEM fails. For this reason, overtemp errors are most often caused by dimmers.

When a dimmer's internal sensors indicate it is running too hot, it sends the signal to the CEM Classic, CEM+, or CEM3, which then reports that an overtemp is occurring. Dimmer modules which are reporting an overtemp can be hot enough to cause burns when touched.

Additional notes:

• Overtemp is not an AF function. Overtemp errors are generated independent of AF cards that are in the rack
• Overtemp messages only appear after the dimmers are brought up above a level of zero
• Overtemp is a bussed signal. This means that if a module is reporting an Overtemp error, it can cause Overtemp errors for adjacent modules to appear

One possible cause of a CEM Classic, CEM+, or CEM3 generating its own overtemp signal is corrosion damage, though there would likely be other problems with the CEM+, and possibly the rack, if corrosion is found.