Trouble Shooting Tips No. 13 - Kraus Micon 200 Boards Modified for Back Light

trouble shooting tips No. 13 - Kraus Micon 200 Boards Modified for Back Light
December 1999

On Kraus SKIL 350 Controllers, transistor Q2 switches power to the heater circuit. The first displays used on the Micon 200, the SKIL 287, had heater circuits and no Back Light. During periods of cold the Controller Board would switch power to the heater circuit. When the SKIL 444 Display with Back Lighting was introduced the heater was not incorporated and instead Kraus used the heater circuit to power the Back Light circuit. As a result they modified the Controller board, as shown in figure 1, to by-pass transistor Q2 and turn the power on constantly so the back light would work. This modification could be also done on the earlier SKIL 252 Controller.
When changing Displays or Controller boards make sure you have the Controller modified or not modified depending which Display is being used!
It should be noted that second generation (Assy 6) and newer SKIL 444 Back Lit Displays now have a control circuit on the Display Board to turn off the Back Light when the Board gets hot (as it would in bright sunshine).
Thus if you find a Micon with the Back Lights not lit, it may simply mean they have switched off from heat! Let the board cool and try it again before changing it.

Trouble Shooting

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