18 Dec
2017
18 Dec
'17
12:06 a.m.
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?
Thanks
Rob
18 Dec
18 Dec
1:07 a.m.
On 2017-Dec-18, at 12:06 AM, Rob Jarratt via cctalk wrote:
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?
It's barely conceivable it could be getting used as a clamp or snubber.
If you haven't found another bridge or rectifiers for the mains rectification,
then keep looking for unseen connections to this bridge.
2:20 a.m.
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.
Regards,
Peter Coghlan.
6:35 a.m.
On Mon, Dec 18, 2017 at 8:06 AM, Rob Jarratt via cctalk
<cctalk at classiccmp.org> wrote:
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?
I don't think it makes sense. With no connections to the other pins
(+ve and -ve DC
out I assume) then there is no DC (or AC) path through the rectifier,
whatever the input,
at least one diode is reverse-biased. Unless you are depending on the
diodes to break
down in a controlled way (and I can't believe it depends on that) then
the bridge will do
nothing.
-tony
2521
days inactive
2521
days old
3 comments
4 participants
participants (4)
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ard.p850ug1＠gmail.com -
bhilpert＠shaw.ca -
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robert.jarratt＠ntlworld.com