williams flash

[rockhouse]

williams flash switch problem
was working ok next time turned on wouldn't start
all solenoids and lights work
all switches in wrong place as per below picture
ones on right correct ones on left incorrect
to start a game press 11
9 and 10 now tilt game
switch test shows no switches closed
replaced 15,16,17,18 on driver board twice in case faulty
any help appreciated

 

[astyy]

It seems a coincidence that they are out by +8 the size of a row or column. Is it possible the connector to the MPU isn't keyed and is one pin offset?

 

[rockhouse]

a good call but no
checked all and all where they should be

 

[astyy]

Interesting problem. Somebody was recently describing jumping each strobe column pin to the row pin in turn to check which switch the MPU thinks is closed. Perhaps there is a similar procedure for your machine to help t/shoot this.

 

[rockhouse]

.

 

[rockhouse]

just done switch test column to row jumpers
results below
column 2,3.5 and 6 activate 2 switches
e.g column 2 activates 1 and 9
column 3 activates 9 and 17 as per diagram e.t.c
column 4 no activity at all
any help appreciated

 

[Moonraker]

First thing I would check is if there is any battery acid damage to the MPU...

 

[lukewells]

Sounds like PIA @ IC11 is not encoding correctly or not diving one of the data lines resulting in wrong interpretation by the CPU

If you are confident that 15,16,17,18 are good, then IC11 is highly suspect

 

[rockhouse]

yep thats the next one to come out
sound like a dentist

 

[rockhouse]

ic 11 replaced still the same
and no battery acid damage has a remote battery

 

[lukewells]

I guess the next thing is to check databus activity between IC11 and the CPU on a scope. Assuming again that 15,16,17,18 and 11 are now good, it appears as if the CPU is unable to correctly read the PIA.

I don't have schematics in front of me at the minute, but I don't think Wms sys3/4 does anything clever with interrupts so I don't think it would be any of the control logic. I need to have a proper think when I am looking at the schems

 

[rockhouse]

short clip if it helps
thanks for any help

 

[rockhouse]

update all column 4 has continuity from 2j2
to 25,26,27,28,29,30,31 and 32
all diodes test ok
all rows in 2j3 1 to 8 have continuity
any one have any thoughts