Laser Scout , Metal detector

[N Cook]

A repair job for next week, UK made in last year or 2

300 GBP machine so worth repairing.

Detects presence of metal but a very broken audio output
like a bad contact but nothing found by prodding.
All surface mount devices. There would appear to
be a negative voltage generator on the board somewhere
that may be wavering.
Anyone recognise this
Texas Instrument (tiny indistinct logo so maybe not TI )
8 pin SM IC numbers on it
22621
18T
A72J
The other ICs I can probably identify

electronic hints and repair briefs
http://homepages.tcp.co.uk/~diverse