Distorted sound or speech, or hum, from a Squawk and Talk board.

Squawk and Talk: distorted sound or hum

Cause: Dried electrolytic capacitors, chiefly C16 and C22; also PIA U7, oxidized legs on the TMS5200 speech chip U8, a bad pot, or cracked joints at J1 (page 69).

Checks

• Check C16 and C22; tantalum parts there were Bally's own fix and may be fine.

Fix

• Replace in order of importance: C15 (10 uF 16 V); C16 and C22 with 6.8 uF 16 V or higher; C36 and C43 (2.2 uF 25 V); and the 1 uF 25 V group (C19, C24, C25, C28, C31, C34, C42), observing polarity.
• Only as a last resort replace C14 (4700 uF 25 V); C27 and C29 rarely need it.
• Swap U7 with U11 to test the PIA, clean the TMS5200 legs and reseat it, swap MPU U10/U11, and reflow J1.

Systems

• Bally MPU AS-2518-35

Related tips

• Squawk and Talk test points
• Bench-test a Squawk and Talk board
• Squawk and Talk stops at four flashes
• The Squawk and Talk test button can lock the board up
• Squawk and Talk supply needs
• Squawk and Talk LED flash codes
• Speech quieter than sound effects until the game warms up
• Squawk & Talk -61 and Say It Again -81 test points

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)