Pre-DCS sound boards are tuned per game

The mixing resistors R22 to R25 on the A-12738 set the balance of speech and effects against music, and their values differ by game. Funhouse has R22 and R25 at 120k and R23 and R24 at 150k (favouring speech); Addams Family has R22 and R25 at 120k and R23 and R24 at 56k (favouring music). A board swapped between games works but sounds noticeably different.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics

Games

• Funhouse
• The Addams Family

Related tips

• Pre-DCS sound board A-12738
• Sound board beep codes before DCS
• Pre-DCS sound cuts out after the game warms up
• Volume stuck at full and buttons do nothing (pre-DCS)
• Adding a line out to the A-12738 sound board
• Pre-DCS speakers pop and get damaged, LM1875 runs hot
• Sound board fuse F501 blows at power-on (A-12738)
• Fitting a manual volume pot to the A-12738

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