Model 478
Troubleshooting Table
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| Problem | Possible Cause | Correction |
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No inbound audio. Power | No AC power to the unit. | Check power supply | ||
| Indicator Light (green) is |
| transformer or wall outlet. | |
| OFF. |
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| Defective analog board. | Check and replace analog |
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| board. |
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No inbound audio: | Defective logic board or | Check and replace logic | ||
| ∙ | Power Indicator Light | touch pad. | board or touch pad. |
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| (green) is ON. |
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| ∙ | LISTEN Indicator Light |
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| (green) is OFF. |
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No inbound audio: | Defective menu speaker, | Check and replace menu | ||
| ∙ | Power Indicator Light | menu mic, or wiring. | speaker, menu mic, or wiring. |
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| (green) is ON. |
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| ∙ | LISTEN Indicator Light |
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| (green) is ON. |
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| Defective analog board. | Check and replace analog |
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| board. |
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Inbound audio distorted. | Defective menu speaker, | Check and replace menu | ||
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| menu mic, or wiring. | speaker, menu mic, or wiring. |
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| Defective analog board. | Check and replace analog |
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| board. |
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No outbound audio. Power | No AC power to the unit. | Check power supply | ||
| Indicator Light (green) is |
| transformer or wall outlet. | |
| OFF. |
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| Defective analog board. | Check and replace analog |
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| board. |
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No outbound audio: | Defective logic board or | Check and replace logic | ||
| ∙ | Power Indicator Light | touch pad. | board or touch pad. |
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| (green) is ON. |
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| ∙ | TALK Indicator Light |
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| (red) is OFF when TALK |
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| SWITCH is pressed. |
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(continued)
3
