Yamaha RX-V677 Not turning on

[afnan]

Hi,
My RX-V677 decided to quit on me.The standby light is not there and when i turn it on it just blinks. I have checked the error codes and there is one `PS3 PRT:127 L` Looks like its a power supply issue. Checked the manual and normal values are
Normal value PS3: 132 to 168 and it monitors 5.5V


I have checked the value of the voltage and it is exactly 5.5V tested. I do get System Version error but i believe it might be because eeprom is not powered up. I have checked these points and the Yellow ones show exact 5.5V. However, the connector highlighted in Green shows 0V. Not sure there should be but i think so.
Any guidance on how to resolve the issue would be appreciated.


PS. I do have soldered all joints on power supply board. I was thinking the power supply might be showing 5.5 v but not sure how to load test? for now even during service mode (brief) the 5.5V email stable.

If I disconnect W108 the device stays on in service mode and does not turn off. But does show the PS3 error. If i connect back W108 (board diagram bottom right) after some time it turns off. Thinking if i should dismantel the bottom board or diagnose on this board?

[прямо]

+5USB is most likely the USB ports 5V supply.
I don't think it is the same as the 5.5V standby voltage.

I also don't see any board at the bottom right in the picture you provided. Or did you mean bottom left?

[gerenis]

Hi,
"127 L" means the supply voltage is too low.
If you measured it using a Digital multimeter, then you should know that on a fluctuating DC voltage, most of the DMM's measure the peak voltage.
Measure it with an oscilloscope to see if there is significant ripple voltage on it. Some ripple is normal, as it is an unregulted supply voltage.
You may visually check that the electrolytic caps that are filtering the +5.6V on the OPERATION (3) PCB are not bulged. C3714, C3715, C3718. Even it they are not bulged, they may have lost significant capacitance.
If the electrolytics are OK, then perhaps the connector to DIGITAL (1) is oxidized or some defective component somewhere is draining too much current from the +5.6V supply.
I have no other idea right now.

[madan1]

SM page 131
ope3 board
check voltage across the bridge rectifier (D3712-d3714), check if the opto is working
check voltage on bridge rectifier D3701
check voltage on C3714/3715 or on connector w3707/3703
check voltages on connector W3704

SM page 132
main board
check voltages on bridge rectifier D1051 and D1040
check voltages on regulators IC103 and ic104