24e7d3a5_FAQs___3M_ESPE_Suomi__Possible_Cause
[Problem] During light emission in continuous mode, an error signal sounds for 2 seconds, the emission is stopped, and the handpiece switches to sleep mode. [Solution] Allow the handpiece to cool for 3 minutes, then start the next exposure by pressing the START button. [Possible Cause] 
The information in the Instructions For Use about intermittent operation has not been observed. (See under the header 'Technical Data - Handpiece.') The handpiece has become overheated in the course of use. The handpiece can be used again once it has cooled down.
FAQs - 3M ESPE Suomi
Possible Cause