Thanks for the replies guys,
I have been trying to get some sense out of this circuit for weeks now! I originally built the circuit from the authors pcb layout but there were too many discrepancies to ever get it to work!
Then perhaps foolishly I built the circuit from the schematic onto veroboard, not realising that the LM339 was connected reversed polarity, so I may have killed that now!
I just wish I could find another ESR meter circuit and then I could start afresh as I am fast running out of patience and parts.
If anyone knows if a 339 can survive reverse polarity or knows of a different ESR circuit I would be very grateful.
Thanks again.................Al