YAMAHA RX-E600 - Auto turn OFF in 2sec after power ON

[2X]

Hello, I have buy a used stereo receiver the YAMAHA RX-E600 with two woofers... the man that have it before told me that when the sound volume rises close to MAX it turned off automatically. I measured the coil of the one woofer and had under the half resistance compare to the other one. But now when I push the button to open it lights for 2sec the LCD and turns off automatically with no speker connected at all. I find the schematics and I measure power supply and indeed when I press the power button gives 4,7V to the relay driver but after to seconds gives 0V and the relay and the radio turn off. Does anyone knows what is this that find short circuit maybe and turn off?

Pdf file - Pages 3 & 4
At the connector (CB254) that is the signal "PRY" for the relay engagement I measured 4.7V
at the "12S" I measured 11.7V
at the DG I measured 0V (Digital Ground)
at the "F1" and "F2" I didn't measure something and this connected to the transformer and I don't know what is

https://youtu.be/hxInJFaXRGc

[mzacharias]

This model predates Yamaha's more sophisticated diagnostic programs.

You should check the output transistors for shorts, check for DC offsets at one or both amp channels during the interval before the power turns back off. Same with checking the various power supplies during this interval.

It is also possible to apply power directly to the main transformer to troubleshoot internal voltages at your leisure. There are severe risks involved with this if you don't have the requisite technical skill.