Succesfully replaced OB2263 clone with a SG6841 soldered in upside down

[anti77]

A cheap 12V 5A power supply was powering my CCTV cameras for 10 years continuously until it didn't.

Based on HM2263 DIP-8, which is an OB2263 clone, seemed shorted internally (VIN just 1.6V). Some sites mentioned SG6841 as a replacement. As I had a bunch of SG6841 at hand, is good that I looked at the datasheet, as pins don't match. But figured out that soldering in the SG6841 from the bottom of the PCB should work as a replacement with just a minor changes:
- bent the pin 5 (RT) over top of the SG6841, as it's not needed
- soldered a bridge on the PCB to have SENSE (original pin 4, under "new" pin 5) on pin 6 of the SG6841
- VIN is not connected, so VDD is enough to power it

What do you know, the PSU now works, no hum, no hiss.

On the reference designs the RI resistor seems the only mismatch, 100k for the OB2263, 26k for the SG6841. I don't think it worth changing as there is no overheat or anything suspicious, considering the value of the power supply I did not bothered to scope out the frequency, if it ain't broke, don't fix it.

Hope this helps someone.

[anti77]

Just an update- at full load with the original 100k at Ri it started whining. I just replaced it with a 27k one, all is well.