Hi Gunnar
I noticed that C107 was getting warm at a supply voltage of 6v, and that D108 ceased working as a zener. C107 is only rated at 6.3v according to the parts list...which is OK til something goes wrong and it gets the full supply voltage across it. Tantalums always put on a good show!?
I had no PWM5V from the processor in my case and Q106 was full on, causing? the "full 6v" to appear across C107...at 13.8v I cant imagine.
73 Steve G4EDG
