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Old 12-08-2017, 02:01 PM   #21
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Join Date: Dec 2010
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Default Re: Question about Yamaha rx-v457 power board

All the rails are up, the MCU should be running. It is either dead or it has decided it is unsafe to power up the main relay.

The signal /PSW (power switch) should be at 5V and drop to 0V when you press the power switch. I would check /PSW at CB456, it then goes to the MCU.

Q452 is a digital transistor (built-in base resistors) and needs at least 3V to turn on, but it's probably OK as PDET can also turn on the (Q451) +5S. Looks OK.

Can you measure the voltages on CB452 and CB453, to see if a signal is coming in that would make the MCU refuse to turn on power.
redwire is offline   Reply With Quote
Old Today, 10:39 AM   #22
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Default Re: Question about Yamaha rx-v457 power board

/PSW at CB456(pin 7) gives nothing even when power on button is pressed.

CB452 -
1 - 5V
3 - 1V

Other pins had no volts or up to 0,20V.

cb453 - pin 5 has highest 0,25V. Other pins have about no volts(read about 0,01...0.15)V
rauno45 is offline   Reply With Quote

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