Hi guys!
I'm here again to find a solution for a little issue on my Duotron pinball.
I've also asked to EM "gurus" here in Italy, but Gottlieb 2 players pinballs had not success, so no one can help me!
Sometimes 1-2 games every 10, the player 1 must play twice the first ball. Then the game continues regular until the end, counting the 2nd ball, the 3rd, etc...
I checked the "1st ball relay" and it starts not energized until the points are scored.
I also checked the unit stepper in the headbox, and the contact between wiper and round disc seems ok.
Any suggestion to solve this problem? Where can I check?

The problem appears also during a 2-player game, and while the player one repeats the 1st ball, the player two repeats the 5th ball (not always, but has happened sometimes).
During a 1-player game (frequently used insted 2-player game), when I lost the 1st ball, the wiper is energized once (you can hear the sound from backbox) then the light of "ball in play" stays on N° 1.
I made a video, but I don't know if is possible to upload here or only on YT.

Ok! I hope the problem is here, caused to dirt!
It's not very easy for me to read these schematics , but I try!
If I have troubles I'll write to you again
Thanks for the moment! I'll check then I let you know...

Hello everybody!
I checked the "Add Player Unit" relay "P". It looked ok but I cleaned it anyway!
Then I played over 10 games in 1 and 2 players mode, all in the correct way ... I'm happy of course, but I havn't figured out the real matter of this problem...
Can anyone teach me to read the schematic? For example the path "P"...
Thanks
Ciao
Loris

Duotron-Page2.jpg

Thanks a lot!!! just one question...
Could be the matter that I play the first ball (in the launch channel) before the complete reset? In this way I close in advance the through switch before the reset sequence? (the mechanical sound is not stopped yet)...

My apologies! I intended as "through switch" the switch in the launch channel for the ball gate return.
So, when the ball is launched, that switch is closed even if the wiper has not completed the rotation due to the switch under the apron.
Is difficult to explain that in italian, let alone in english!!!
Mostly I don't know well the EM pinballs!!! Double

Hi guys! The problem is definitively disappeared. I had to change the backelite flange of the player unit. The one I rebuilt with my own hands (unfortunately the flange was broken when I got the pinball) was not too good... the spring contacts were not perfectly alligned and the contact was unreliable... But now it works great!!! Thanks again to all!!!
Ciao