Hey everyone, I'm hoping someone can help me out and that this is a short within the mini-playfield and not a larger board issue...

For people who have a Doctor Who machine, you know the sequence that happens when the time expander isn't lit and you get a ball into one of the locks? how it makes that spacey-wacey sound and then pops the ball back out of the lock?

my machine is doing that any time mini playfield gets hit by the ball, and if the ball does go into the lock even when the time expander should be lit, it still kicks it back out at me. sometimes it even does it on it's own without being hit. I've also had a few times where after I go into the menu and run mini-playfield tests (which all show no errors), once I get the glass back on and hit start, the playfield which usually goes up and down once after a restart, will go up and down repeatedly over and over until I open the coin door and open the menu.

any thoughts? I really hope it's not something in the board, but this is something I haven't seen before.

Update: So after taking out the MPF and cleaning all of the sensors/contacts, the problem persisted. A switch test revealed switch 77 (right opto) was open (should be closed). I ordered a new set of opto's and replaced them. there was a crack and quite a bit of yellowing on the transmit LED that i replaced. put the whole thing back together. The problem still persists. A multimeter test of the IR receiver switch (its the only part I can reach with probes when the machine is assembled shows that the correct voltage is going to the wires, and if it bypass the switch by contacting the leads with a piece of wire, the test chimes and shows closed but only for a moment with each contact. I cannot get it to remain closed with continued contact. Any ideas?