Seems Pinkong sorted out the problem...Cut n Pasted from elsewhere>
"I replaced the resistors first on the optic board and tested same error, as this was easy.
So I then removed the LM339 on the optic board (only one on FT) did I say I hate removing small components like these, about an hour of desoldering and removing as it was in a tight spot and I have damaged traces before doing this on a PCB so was extra careful.

Added a socket (to make replacing the LM339 easy if it ever happens again + they are easier to solder in than a chip no worries about to much heat ) put in the new LM339 no errors

Woo hoo all working correctly! My diagnoses was correct and now Fish Tales is working correctly.

Not bad for a $3.60 fix"
Cheers for the replies,
Andy,