Odd Connections to Rectifier?

Peter Coghlan cctalk at beyondthepale.ie
Mon Dec 18 04:20:29 CST 2017

> I am reverse engineering the schematic for the input stage of my H7862 PSU.
> I have come across a KBU6J bridge rectifier which seems to be connected only
> to the two middle pins, which are the AC inputs. I can't see any other
> connections. Before I desolder it to verify there are no connections I can't
> see, does this make any sense?

If it is the main rectifier, continuity checks should show a dead short from
the other two pins to the main smoothing capacitor(s) or maybe a very low
resistance through a surge limiting resistor or inductor either of which should
be easy to spot once you know what to look for.

If it is not the main rectifier, could the AC inputs be connected across a
current sensing resistor in the mains input with the DC outputs going to an
optoisolator or something like that?  Seems a bit unlikely though as the
voltage drop across the rectifier would likely be too large compared to the
voltage available across any current sensing resistor.

Peter Coghlan.

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