Hi folks,
Does anyone have time to walk me through an explanation of how this circuit works on a Target Alpha? There are 4 lanes that are involved - 2 rollover lanes at the top of the pf and two lanes at the bottom that alternate being lit and scoring 5,000 when lit, or scoring 500 when not lit. The scoring works correctly - that is, when the ball goes through a lit lane, it scores 5,000 pts and when it goes through a non-lit lane, it scores 500 pts. The problem is that I believe the lit lanes should alternate (when a 10 pt switch is activated, I think), and there is no alternating - the same lanes stay lit all the time. But it hasn't worked since I've been working on the machine, so maybe I'm misunderstanding what's supposed to cause the lanes to alternate...doesn't really say on the rules card.

So I'm looking at the schematic and it looks like the FS relay (00-90 stepper unit) and A relay (alternating relay) should work together to make this happen. It looks like a pretty simple circuit, but I'm confused by a few things:

1. What is the "5 pos. sequence completed switch" accomplishing? Looks like no matter which state it's in, there is a connection for the A relay depending on the make-break on FS on the right side of the circuit. So what's the point of that sequence completed switch?

2. What does the FS (1 : 1) marking mean in the "00-90" Unit Relay circuit?

3. Is the "On Add "Player" Unit" switch on the right side of the circuit physically on the coin unit in front of the chimes?

It looks like the "00-90" unit relay should get a pulse every time the M (or is that an "N"?) relay fires, which should change the state of the FS make-break, and the FS (1 : 1) switch? I assume it advances that little FS stepper each time it fires. Maybe I'm not understanding how the alternating is supposed to happen during gameplay...

If I press the A relay to the energized position with my finger, it does alternate the lights and scoring for the lanes correctly.... it just doesn't seem to get a signal to energize from the playfield switches. The coil is good - I can jumper 24V to the right side of the relay and it energizes. It looks like there are only 2 switches involved in getting power to the A relay, so I should be able to track down the problem there, but I'd like to better understand the whole circuit. I hope I explained this clearly.

Thanks in advance for the help!
alternating circuit (resized).JPG

Thanks Mike. So that (1 : 1) indicates that the switch just alternates between on and off each time the relay is fired? Why is the "on add player unit" switch involved...does that have to do with the match feature?

Well, thanks for all the input. I took the FS completely apart and cleaned everything, gapped those switches on top, cleaned and lubed the circuit board and moving arms...and it works! yeah! Apparently, it's the 100 pt relay that makes the FS rotate - so it's the pop bumpers that make the lanes alternate. Should have known - Gottlieb loves using those pop bumpers to alternate stuff.

Anyway, thank again for all the information....I love this forum! I'll mark this thread as solved - thanks for the help, guys!

I haven't seen Howard R in a while though...anybody know if he's OK? He usually chimes in on these things immediately.

No problems, Howard....just wanted to make sure that you're OK. I missed your pinball smarts trying to get this Target Alpha up and running, but thankfully there are always people willing to help.