What I found is pin 10 (ground) of all 3 U301~3 has 0.03V. But pin 17 of U303 has perfect zero volt. I think 0.03V within same chip is a lot leaks or current. I have 3 same type of chips which gave same result of 0.032~0.035V. Without chip, the socket's pin 20 goes to +7.35 and pin 10 has 0.0215V. My scope shows the pin 10 without chip 22~26mVpp ripples. All 3 chip's pin 10 are very noisy. Maybe it is because pin 10 (7) and pin 17 (2) are on different ground plane? So +7.5V current flows into the ground changing +7.5V to +7.35. But why it goes to 4.5V when U303 is inserted?
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