Hi, Need some advice on a party zone machine.
It all started after a couple of hours of good gaming...
The wires for the DJ's jaw snapped from the coil and shorted the switch matrix.
We resoldered the jaw coil and then the machine would not boot, just telling us to check Fuse F114 and F115.
The F115 3/4A was blowing all the time so we decided to change the U20 chip and get it socketed while at it.
Now with a fresh U20 the machine booted and all switches seems to work!....almost
All switches except Flipper left and right is working, we have checked this in the switch edges test in the diagnostics.
Turned off the machine, measured the U20 chip to make sure it's still good. And it was.
Since this is not the fliptronics version i supose these signals comes from the driver board by the two opto couplers U7
and U8, performed a diode test on thoose. Seems OK! Measured all the diodes on the lower part of the MPU board. All OK!
I've googled a lot about U20 disasters and many states that U14 is a good candidate to get co-fried with the U20.
Now, Is it possible that this U14 chip also could be blown even that other switches in both the row and column of the matrix works?
Trying to understand the circuit
Can i test the flipper inputs by jumpering between J207 (pin 1) and J209 (pin 1 and 2)? Or is that only possible on a
fliptronic version? (Would make sense)