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Philips 170S5 no power ON - PSU ok

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tozito

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Dear Forum, I'll need your contribution on this one... the screen doesn't power ON, also LED on control board is all OFF; so far I've been able to check PSU as OK, all the output are OK on osciloscope (12V - 5V - 3,3V). Also the 2,5V regulator (7507) on scaler board is OK, 12Mhz oscilator OK, TL431 (7444) output ref voltage is OK.
When pressing power button on control board, voltage goes from 3,3V to 0V on PIN 2 of CPU (7301) - from "K_PWR" bus. CPU as correct voltage on VCC... do I have a faulty CPU? or could you think of anything else to goes from?
Thanks to all.
Best Regards.
 

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