Big League Baseball by Chicago Coin 1975

Big League Baseball by Chicago Coin.  This baseball is the digital version made in 1975.  The circuit board is populated with first generation TTL logic chips.  We may have had more fun fixing this than playing it.  I (Lee) just love this old circuitry.  Brings back memories of $300 logic probes.  Now a logic probe is $20 bucks if you can find one.  The invoice notes follow.

08/12/2012 16:32:10  Cleaned the game board. 1 soap and water wash, 3 acid washes, 2 baking soda washes. Each time brushed and blown dry then left in the sun till very dry. Sanded and dremel wire wheel brush as much as possible. The board had rat urine over 75% of the surface. This over 2 days. Will attempt repair next.

08/20/2012 12:45:31  replaced power supply with new modern switching regulated unit. Replaced over 100 edge connector pins. Repaired fuse holders. Replaced all triac transistors (15), Replaced all current limiting resistors with metal oxide type. Replaced 9 IC's and sockets. Finally turned it on. Game works but right display not working. Played a few games. Found several more IC's to replace. There is a LOT of corrosion damage yet to fix. This is becoming a pain in the neck.

08/21/2012 10:21:13  Replaced several more IC's, this fixed the right display. Replaced all electrolytic capacitors on sound board - works fine. Found both pitch deflection coils (Curve and Slider) are burned up and shorted. Coils placed on order. Fixed varistor on Bat coil. Still have some corrosion mediation to do on several more IC's. Still need to make missing back doors. Waiting on parts - coils.

08/23/2012 16:28:22  Found the right Nixie display had a bad IC - a 7447. Not an easy one to find. It would only count to 20 and recycle. Fixed it and put 3 new locks on the front doors and glass lock. Still need to make the back doors. Still waiting for the coils we ordered. Getting close to finish on this project.

08/29/2012 16:57:22  Coils installed in Curve and Slider circuits. Found open circuit to Home Run target. Free credit on score threshold fixed (more IC's). Option jumper problems fixed (yes... more IC's). Intermittent goofy score, pitch motor run-away, strange sounds fixed - was voltage drop on edge connectors - built up pads with fresh solder. Also decided to replace all pull-up resistors on switch circuits (20). Cut a sheet of plywood and made top and bottom back doors. Tested, tested, tested, done.


















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