But the current source was not only connected to the capacitor. The capacitor was replaced, but no difference. It seems like to much current is consumed from the current source. The voltage over the capacitor never exceeded 20.4 V which was not enough to get the two of the comparators to change polarity. A resistor ladder circuit and a number of comparators generate the BUS DC LO L, BUS AC LO L and an internal signal which causes the clock signal to the main PWM switch.

The blue marked area is a current source circuit which is fed by incoming raw DC and which charges a 50uF capacitor which thus creates a nice ramp signal.

The schematics above describes the 5V regulator of the H777 power supply.