Midway 4-Player 25" Dedicated Video Game - Manual (Page 108)

Troubleshooting 6-6
Audio Troubleshooting Table
SYMPTOM CAUSE REQUIRED ACTION
Improper volume
setting
1. From Main Menu, choose VOLUME LEVEL.
Check that Attract Music is on (enabled). Verify
that all volume levels are set well above zero.
2. If necessary, change levels to make VGM
audible.
• No audio
• Video is present
•
VGM (video game machine)
appears to operate normally Faulty SIO Board
1. From Main Menu, enter Diagnostics Menu.
Select SOUND SUBSYSTEM TEST. Test
checks entire sound system.
2. Run power-up self-test sequence. Note errors
that VGM finds during tests. Compare Sound I/O
Board (SIO) LEDs with LED indicator status
charts. Note discrepancies.
3. Verify proper operation of SIO Board by placing
it in working VGM.
4. If board is faulty, replace it.
Faulty wiring
1. Check that cabinet wiring is correct for this VGM.
2. Verify that cabinet wiring provides separate
wires (not common return) for each speaker.
3. Check connection of all cabinet ground wires.
4. Repair faulty wiring.
• Constant low hum from all
speakers.
Faulty power supply
Using 2 Volt AC setting on digital voltmeter,
measure voltages at speaker terminals. Any
reading indicates ripple or noise. In that case,
service power supply.
Faulty or improper
speaker
1. Turn off VGM power. Remove grilles and check
speakers. Assure that speakers are full range
(100 to 10,000 Hz) and rated for at least 20 W.
Woofers must be rated for at least 40 W.
2. Verify proper speaker operation by connecting
speaker in question to working VGM.
3. If speaker is faulty, replace it.
• Audio is distorted, muffled or
has missing frequencies.
Faulty wiring
1. Multiple-speaker installations: Check for
reversed wires at one speaker. Weak low
frequencies and thin or hollow sound quality is
symptom of incorrectly phased speakers. Sound
tests may not detect this condition, but you can
hear it during VGM operation.
2. Repair faulty wiring.
Faulty speaker
1. From Main Menu, choose SOUND TEST.
Recheck speakers with audio signals in test.
2. Verify proper speaker operation by connecting
speaker in question to working VGM.
3. If speaker is faulty, replace it.
Faulty circuit board
1. From Main Menu, enter Diagnostics Menu.
Select SOUND SUBSYSTEM TEST. Test
checks entire sound system.
2. Run power-up self-test sequence. Note errors
that VGM finds during tests. Compare circuit
board LEDs with LED indicator status charts.
Note discrepancies.
3. Verify SIO Board operation by connecting board
to working VGM.
4. If board is faulty, replace it.
•
Dead sound channel
Faulty wiring
1. Verify that cabinet wiring is correct. Assure that
all speakers connect to audio wires. Check for
broken or shorted wires.
2. Repair faulty wiring.