The TNY274 PWM CI exploded. After changing tny274, the source still doesn't work or fluctuate. The strange thing is that at the entrance of the rectifier bridge there is 110VAC, but at the positive and negative terminals there is no voltage at all. I didn't get to change the photo coupler and the 9V1 zener close to the tny is fine. The electrolytic 120uF C907 has the correct capacitance. The rectifier bridge is ok with that.
The photo coupler may be damaged (the original is the TCET1103G). Can I use the 817 instead of the TCET1103G?

Change TCET1103G to 817.

I also mistrusted the photo coupler, I even replaced it, as it didn't solve it, I ended up discovering the problem, it was my multimeter that was deceiving me with the measurements. The defect was and only the tny274 burned. Sorry to make colleagues waste their time.