The pre-DCS WPC sound board makes only a few blurps at power-up and no bong, and no game sounds. A control line (U29 pin 11) pulses when it should sit high.

WPC sound board silent, no power-up bong: try the RAM first

Cause: A failed static RAM chip on the sound board. RAM can't be tested reliably in circuit.

Checks

• Listen for the power-up bong: it means the sound ROMs passed and the program is running, so a board that bongs but makes no other sound has a different fault.
• Compare key logic pins with a working board if one is available.

Fix

• Remove and socket the sound board RAM and fit a new one before swapping other chips.

Systems

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

Related tips

• Sound board beep codes at power-on (pre-DCS)
• Pre-DCS sound board faults by symptom
• WPC sound board versions
• WPC-89 sound board layout
• The WPC sound board runs on its own
• No audio output at all from the sound board
• Sound board RAM error at U9, wrong call-outs or no sound: replace the U9 RAM
• Random stray sounds in attract mode after changing the CPU board

Source: Pinball Repair help group!! (Facebook group)