Viper35 waking up issue.

[Dhruv_Challawala]

Hello,

For the past few days, I’ve been trying to operate the VIPer35 quasi-resonant  offline high-voltage converter, but I haven't been able to get any output. I attempted to bypass or disconnect the output of the PC817 optocoupler and also tried shorting it—still, no pulses were generated. I also connected the ZCD pin directly to ground and then to VDD in another attempt, but there was still no output. Additionally, I tried powering the VDD directly with 15V and even applied 230V AC through a variac, but no pulses appeared.

I need guidance on how to generate pulses or how to properly trigger the VIPer35 IC.

In the oscilloscope yellow graph is Vds and Blue graph is Vdd

[Peter BENSCH]

Welcome @Dhruv_Challawala, to the community!

A note in advance: In your photo, I can see the usual USB socket under the screen, which can be used to save screenshots to a USB stick. Their use and better readability would greatly improve support from other community members.

When I look at the scope photo, VDD only seems to reach the start-up threshold for a very short time (if at all), but then immediately drops again, which is probably below the soft start and start-up time. Without transformer parameters or further scope images of VDD, drain voltage at T1.2 and possibly the voltage at T1.4 (please use USB stick), as well as higher resolution schematics for better readability (the value of e.g. R102 is absolutely unreadable), you won't be able to help much.

Regards
/Peter