Cleaning minor battery corrosion on the CPU board before fitting NVRAM
Steps
- Remove the batteries and desolder the on-board battery holder.
- Neutralise the corrosion with white vinegar (alkaline battery leakage is a base), scrubbing with a toothbrush, then rinse and clean with isopropyl alcohol and let it dry.
- Inspect every part and trace the corrosion touched; replace affected parts and sand any corroded copper back to bare metal, then seal it.
- Clean the connectors and cable ends near the damage the same way.
- If you fit NVRAM and remove the batteries for good, diode D23 (a 1N5817 that stops the batteries powering the whole board) can be replaced with a wire jumper, and D25 can be clipped or left; no other jumpers are needed where the holder was.
Battery electrolyte is corrosive: wear gloves and eye protection.
Games
Related tips
- Fitting a remote AA battery pack
- Fit a remote AA battery pack with a blocking diode
- New CPU batteries go flat quickly
- Battery power not reaching the RAM: diode D2
- Combining two-chip CPU code into one 27512 for 5C
Source: Pinball Repair help group!! (Facebook group)