I'm nearing completion on my King Pin but have a problem that's driving me crazy and wondered if anyone could help.

When I start a game by any method (start button, coin switch, start relay) instead of starting once it will start anything between once, several times, or continuously until I turn the game off.
By start, I mean the motor turns constantly and the target bank resets over and over again.
The score reels reset to zero and do not try to reset further so that part seems OK

I think I can see why it is happening - the start relay (S) is staying "locked on" and failing to drop out when the motor rotates - but I can't see what is causing that.

From the schematic (see extract attached) I understand that the lock in switch on S should be released by motor switch 2B
I've checked that this switch opens correctly, and that the tabs on the switch blades are not touching the tabs of any other motor switch

I've also checked that the replay button switch and the two coin switches are open

As I understand it that should isolate every source of power to the S relay coil, and yet it is remaining energised

Has anyone come across this kind of problem before, or got any ideas that might help?

Many thanks
David

start circuit001 (resized).jpg

Hi Richard
Thanks for the reply

Yes all three of those are operating correctly.

Obviously when the S relay is locked in it means that the S relay switch you refer to is closed hence the reason I think I am getting multiple resets of the target bank.

currieddog - the A relay is pulling in and releasing smoothly for each start the game does

MarkG -
if I block the lock in switch all that happens when I press start is the motor turns to the next rest stop
if I unplug the 1st coin chute adjustment plug the problem remains, and this the same if I also unplug the 2nd coin chute adjustment switch

no other relays stick on with the S

currieddog where is the M/B you refer to on the schematic please?
The only one I can see is at I 11 but that doesn't seem to lead into S?

Do you think residual magnetism or wear on the relay latch plate might do this?
If I put a bit of gentle pressure on the return spring on the relay the game seems better
I don't think the spring itself is at fault as I've swapped it twice now for ones on little used but working relays elsewhere in the game and it doesn't make any difference

I've just fitted a stronger return spring to the relay latch and, fingers crossed, it is only resetting once each time

I'll need to give it plenty of play to make sure the fix sticks.
If it does I may try and swap out the latch plate for one that has seen less use and put the original return spring back on

edednedy thanks for your comment. That was something I'd already tried in the earlier stages of trying to fix this, but doing that disables power to S completely - I assume because it in effect permanently opens the anti cheat NC switch on the front door (at I 13 on the schematic)

Just to say that fix seems to have solved the problem,
I've had no further multiple restarts.
Thanks for all your help.
David