I'm experiencing odd behaviour in my TOM with switches registering and not registering sometimes.

Recently a couple of fuses have blown, first for the left magnet save, then later for the trough / ball launch.

Now I'm seeing occasional issues with some switches. A couple of times the left flipper has triggered a trunk hit while choosing a mode before ball launch. A couple times actual trunk hits in game have not registered. And it seems fairly often that the right outlane eddy sensor is missing the ball entering the right outlane and fairly often that the right magnet save is triggering on the right inlane switch, and sometimes on no switch at all.

Voltage at TP3 is 12.0V dead on.
Voltage at TP2 is ranging from 5.03 to 5.08 V.

I'm not seeing anything to indicate power issues, ie no Williams reset, LED 1-7 on the driver board are all solidly lit.

The switches I've noticed acting up are not related by row or column on the switch matrix.

I'm thinking I may have a failing chip at U16, U17, U18, U19, or U20, and I should replace these. Does anyone have any thoughts that this may be the best next step (or worst next step?)

Just in case it's worth mentioning, I have pinbits auto adjusting eddy sensors on trunk and inlanes, and also Ingo's Leon board on the trunk, though I doubt any of these are power drains.

Can I place my Doctor Who cpu in the Theatre of Magic to prove or disprove that the problem is somewhere on the CPU? Doctor Who is WPC-Fliptronics 2, where Theatre of Magic is WPC-Security. The cpu both have the same connectors onboard, but slightly different chips and layout. I'm afraid of blowing up other stuff if they are not compatible.

Ok, thanks that's what I thought. Yet another case of regret over selling my NF. :p I guess I'll have to order chips and replace U16-U20 and see if that does the trick then.

Unfortunatelyl U16-U20 was chasing my tail. Replaced them all and no change on the issues with right magnet save. Unsure about the trunk activation with left flipper as it has only happened a couple of times, not too repeatable. Though I now notice that if I press the left flipper button very slowly I can get it to machine gun 2 or 3 times.

Tomorrow I will try pulling the pinbits boards and Ingo's board and see if somehow one of them is scrambling other stuff.

In the meantime, this caused me to look closer at the eddy sensor, and there's nothing to look at. WTF, just a resistor buried in the PF? How does that sense anything?