Hi all,

Sorted it out! After replacing the oscillator, the problem remained, so I
started looking elsewhere. In the end I found it. It retrospect the mistake
was obvious. The design prototype was built on stripboard but lack of space
up top required a wire link, which for the sake of simplicity I had created
with some under board wiring. The only problem was one of these wires had
pocket through the PCB and touched the wire connecting the PIC to the
crystal. The heat of the soldering had melted the insulation, shorting the
wire (which was +ve) to the oscillator. If I pushed of pulled the crystal
this seperated the two wires by just enough to break the short and allow the
crystal to oscillate.
So infact, this had nothing to do with oscillators and more to do with
avoiding under-board wiring.
One of those mistakes where looking back it seems so obvious (like when I
spent two hours debugging code only to find I'd put movlw 12 instead of
d'12')....

Ben

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