Cleaning out the Garage and came accross a replacement CDI I purchased for the old boat which had a 1987 Yammy 70.

It is a Yamaha part made by Hitachi with TIA03-12 and 809 K stamped on the unit.

Ultimate problem was a faulty loom so ended up with a spare CDI (grrr) .  Seem to remember it cost about $250 when purchased.  Happy to take $100.

It did work as I swapped it out with my old unit, then once the problem reoccured proved that the OB mech was wrong.

Happy to test (if there is a simple test with multimeter) but will refund if your OB mechanic says it is no good.

Here is the same unit on ebay.

http://www.ebay.co.uk/itm/YAMAHA-70-HP-OUTBOARD-MOTOR-CDI-UNIT-1984-1991-TIA03-12A-/221171524583?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D4972344375734870228%26pid%3D100011%26prg%3D1005%26rk%3D2%26sd%3D321033022810%26