On Sat, 19 May 2012 13:52:58 +0100, "N_Cook" put
finger to keyboard and composed:

I now see someone else has been here before and ground off IC5

music-electronics-forum.com/t10881/

Did you see the following post in that thread?

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Have you noticed that pins 1 and 4 (Vcc and COM) of IC5 are reversed
on the schematic (if this is IR21531)?
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I noticed on the one i'm working on. I was hoping it was an error in
the schematic but it is not.

I verifyed continuity to ground at pin 1.

So the IR21531 is not a drop in replacement as far as I can tell. I
have looked at just about every self oscilating half bridge drive they
sell and nothing that has pins 1 and 4 swapped.
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- Franc Zabkar
--
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