Jennings 721 723 reel motor, and general help.

[Fortytwo]

Hello,
  I have two slots on my bench from a buddy.  One is completely together 723, and the other is completely apart.  It looks like I have every part for both except the bell bells and maybe a bracket or two.   The deal is is I can fix the 723 I get all the "spare parts". Which will include a complete slot.  And I can diagnose parts by using the good machine.
  So the 723s issue is;  when it powers on the reels spin fine, noisy but fine.   After a few spins they slow down or stop spinning completely.  I have checked the voltage and it appears I'm still getting voltage, but my thought is amperage.  Some solid state relay or  something is over heating.  I have tried both reel mechs with the same result.  If I fiddle with the toggle switch on the reels it sometime speeds back up.  Is the a purpose other than stopping the reels for that toggle?  Could I just bypass it to eliminate the contacts in it?

  The 721 is apart.  The power supply is out and also the little transistor board that mounts to the back board behind the hopper.  What does this little board do?

Any help is appreciated.
Thanks
FortyTwo

[Fortytwo]

Hello,
  After doing some tracing and jump testing I have determined that the issue is in the transistor driver board.  I swapped them and I don't even get movement from the second.  So I was going to try replacement of the transistors and possibily the drivers.  Are these avalible?  Is there a better replacement for them like a tip?

Thanks
Ed

[ramegoom]

Are you referring to this one?

[Fortytwo]

Yup, the small board attached to the lower half.  I found mouser has the parts for about $2 per triad driver set.   I will rebuild both. 
  Is it recommend to replace the caps on the power supply board? 

I have the 721 all together,  the small board needs parts also, when swapped it does the same as the other.   
  The main issue with this one is the logic board doesn't seem to boot correctly.  I will wait until I get the parts from mouser and completely rebuild both boards.
Thx
Ed

[ramegoom]

The Logic board on this machine is a bear...lots of room for problems being as there are jumpers all over the board. The battery has probably leaked, causing damage to the board and acid leaching under one or more of the IC's. So, you need to go thru it with a fine-tooth comb and look for damage.

It's pretty unusual to find the boards without some sort of problem. These logic boards were designed prior to microprocessor technology, so they're all ancient TTL logic (with a bit of early CMOS mixed in). There are schematics out there that cover the logic board, generically anyway.

[Fortytwo]

This was my fear.  I believe the "working" board is not behaving correctly.  After I recap the ps and fix the triad board I hope it works correctly.  When I trigger a payout it runs the hopper.   When I manually trigger the coin count switch it seems to lock it up.  I could be holding the switch in too long or short though. 
 
Ed

[ramegoom]

Triacs and opto-couplers are readily available. The logic board has several drivers on it as well. Here is a link to a diagram of a typical logic board with the drivers. You can print it out, and it makes a good reference:
http://www.ramegoom.com/john/jennings400/logic-transistor-ID.jpg