Hi Bernd,
there is no need to cut anything on board, just remove both regulators (78L05 and 79L05) and measure voltage between pin 5 of 7660 and GND. You should measure some 8.5 V to 10 V, if no than the most likely 7660 will be the problem, but first make sure that both electrolytics (marked on picture) are 25 V.
And finaly inspect diode D8.
If problem after all those remain trace line from pin 7 of 7660 and inspect everything on that line.
Regards Marko.
there is no need to cut anything on board, just remove both regulators (78L05 and 79L05) and measure voltage between pin 5 of 7660 and GND. You should measure some 8.5 V to 10 V, if no than the most likely 7660 will be the problem, but first make sure that both electrolytics (marked on picture) are 25 V.
And finaly inspect diode D8.
If problem after all those remain trace line from pin 7 of 7660 and inspect everything on that line.
Regards Marko.
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