Batteries that should last years go flat in a few days or weeks.

Batteries die within days or weeks: diode D1

Cause: Diode D1 (1N5817) has failed, so the batteries try to power the whole CPU board instead of just the RAM.

Checks

• Test D1 and D2 with the game off (D2 readings as in the D2 entry).

Fix

• Replace D1 with a 1N5817 (a 1N4001 works in a pinch, with a little more voltage drop).

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Battery power not reaching the RAM: diode D2
• The batteries also power the U9 ASIC clock
• Changing the CPU batteries without losing settings
• New batteries but still losing settings: test the holder
• Switch matrix row fails with good switches and diodes: battery-damaged CPU board
• Coin door Begin Test button does nothing: acid-broken trace on the CPU board
• "Factory Setting" or "Adjustment Failure" at power-on
• Settings lost because battery voltage at the RAM is too low

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)