Stern WPT- flipper issue - possible signal problem?

[SteadyP]

Hi guys, hopefully someone will know about/ have experienced this issue on a WPT or similar Stern SAM era game. When hitting a shot during gameplay- The pin will occasionally keep either the left or right flippers held up and the coil is energising (audibly). This problem just appears out of nowhere and is intermittent. When it does happen it affects the upper left and right flippers also. I.e. both the right hand side upper and lower right flippers will stay up. They will release by themselves after a while. Or they’d drop immediately if you turned the game off. I don’t think it’s mechanical as I recently checked all the flipper mechs when replacing with new coil stop ends. Any ideas would be greatly appreciated

 

[Fantazia2]

Sticky buttons? or Leaf switches for the buttons need adjusting/gapping?

 

[SteadyP]

I’ve looked at the leaf switches briefly and couldn’t spot any obvious issues. Just very weird that it doesn’t happen often- it’s my dad’s game so I haven’t got access tonight to have a proper look through it. I was thinking it could be a lose connection somewhere- not sure if the flippers have a controller board somewhere which cuts off the power once the EOS is activated ? Switches 1 and 2 aren’t in use for WPT according to the manual- these are showing as tech alerts when I cycled the service menu. My understanding was that the EOS switches on Sterns aren’t really needed. Bit of a head scratcher

 

[Moonraker]

First thing to try is to replace to missing out incomplete EOS switches and see if that make a difference. Ignore the EOS aren't need on Sterns, I've known too many stem EOS problems over the years.

 

[JWG9999]

not sure if the flippers have a controller board somewhere which cuts off the power once the EOS is activated ?

I can't think what's causing the problem you describe but...

I had a flipper problem myself on my WPT recently and spent some time on it. There isn't a controller board for the flippers. The whole flipper circuit is shown on page 103 of the manual. The flippers are controlled through dedicated switches on J3 of the CPU and driven from J10 on the Power Board. There's a description of how the EOS switches work on that page too.

Hope that helps a bit.

 

[JWG9999]

This problem got stuck in my head! Maybe it's simply the flipper buttons are sticking. I'd suggest take them off, check them out, clean them up - or replace them.

 

[SteadyP]

I have my suspicions about this also- hopefully it’s just this simple issue. I’ve seen flippers lock up when transistors fails and this behaves differently. Mainly the right flippers so possibly right button spring has a weak return spring inside