I started to look at the driver and CPU board and noticed that there was some corrosion on some of the transistors (special solenoid drivers) and also noticed some clipped wires on the memory protection and diagnostic switch connector.

Driver board:

  • Desoldered the 40 head pins
  • Desoldered the battery holder (will be replaced with a NVRAM)
  • Desoldered the 5101

CPU board:

  • Desoldered 40 pin interboard connector
  • Desoldered the transistors (Q63, Q65, Q67, Q69, Q71, Q73, Q75, Q77) and resistors (r149-r150) in the lamp column drive section.
  • Desoldered the transistors (Q2, Q4, Q6, Q8, Q10, Q12) and (Q1, Q3, Q5, Q7, Q9, Q11) in the special solenoid drivers section.

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