Have a TZ where all the clock optos do not register (in clock test they have a box with an x through it). I have the Ingo clock board, and have verified it works as i have an external test fixture - so problem is on the machine.

How to i test the 9th switch column with jumpers - normally you would jumper between J209 and j207 for the switches in the 8x8 matrix, however the 9th column apparently comes from J5-1 on the 8 driver PCB in the top right of the backbox. So i would have assumed i could jumper between this pin (J5-1) and J209 to get switches 91-98 - or am i doing this wrong? I get no luck doing this.

I would like to verify the MPU is not the problem before taking further steps

Thanks, but J208 is exactly the same as J209 - they are in parallel

zaza - you were spot on. After a lot of frustration is was my stupid fault - i had one connector wrong on the power driver board (J103 into J105), plus had the 2 wire connection to the clock board just off - so 2 problems combining to show all sorts of funky symptoms - didn't help i knew no history of the game!

Thanks

Rob