Caveat emptoris good advice in general, but in the wilds of eBay, being careful with what you buy could be life-saving. To wit, we present [Les Wright]’steardown and very ginger power-up of an eBay tattoo-removal laser power supply. ...
Once you have found the opto-coupler, clean up by removing all the parts associated on the output side of of the opto, meaning across the pins which may be towards the output side of the SMPS PCB. And connect or integrate these pins of the opto with the assembled circuit using the TL43...