who knows maybe someone meet this problem in the past

Have you measured the B+ to make sure it's not over voltage? Leaky Caps might produce this issue in the Power Supply. My Onkyo is only 52 volts Leaky diodes might produce a similar problem elsewhere in the circuit maybe leading to logic chip running the Diag.

kv

 

Here's an interesting video, wrong model Number but, maybe you can gleen something from the video.

kv

Edit: He thought replacing that cap would change the voltage in the end but it didn't, more like corrected the frequency or something.

Thanks.... I already saw that video

 

You have a voltage which you say is good, and a sensor that says it's bad.

How is the voltages sensed? A voltage divider? A voltage comparator?

Measure the voltage at the same point the sensor measures the voltage.

 

Ok.... what voltage should I measure exactly

 

If there are more than one, measure all of them.

make a chart:

Voltage at power supply TP at sensing point


If the sensor is lying to you, you need to know how that voltage gets from the test point in the power supply to the sensor. there could be some defective components inline or the sensing device itself is messed up.

 

Thanks.....
well all is good but it's very hard to access the main cpu legs cause it's located down in the amp box and inaccessible for measurement all what I can do is to measure the main voltages from the power supply, it's seem the builded this av receiver for no repair or just change and replace the electronics cards