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Table 3-6 Advanced-level troubleshooting
Problem | Check point and | Remedy | ||
| probable cause |
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Adjust GAIN control with A/C | 1. IF amplifier | 1. Replace IF amplifier. | ||
SEA control set at minimum. | 2. | Signal cable between | 2. | Check continuity and isolation of |
Marks and legends appear |
| antenna and display |
| coaxial cable. (Note: Disconnect |
but no noise or echo. |
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| the plug and lugs at both ends of |
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| coaxial cable before checking it |
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| by ohmmeter.) |
| 3. | Video Amplifier Board | 3. | Check video coax line for secure |
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| connection. If connection is good, |
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| replace SPU Board. |
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Marks, legends and noise | 1. Magnetron | 1. Check magnetron current. | ||
appear but no echo. | 2. | Modulator Board | 2. | Replace Modulator Board. |
(Transmission leak, | 3. | SPU Board | 3. | Replace SPU Board. |
representing own ship |
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position, is absent.) |
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Picture not updated | 1. Bearing Signal Generator | 1. Check the connection of signal | ||
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| Board (scanner unit) |
| cable. |
| 2. | SPU Board | 2. | Replace SPU Board. |
| 3. | Video lockup | 3. | Turn off and on radar. |
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Incorrect orientation of | 1. SPU Board | 1. The message "HD SIG | ||
picture |
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| MISSING" appears when the |
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| heading pulse is not received |
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| during |
| 2. | Gyro Interface | 2. | Replace gyro interface. |
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Tuning manually adjusted | 1. Deteriorated magnetron | 1. With radar transmitting on 48 nm | ||
but poor sensitivity |
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| range, check magnetron |
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| current. If current is below normal |
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| value, magnetron may be |
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| defective. Replace magnetron. |
| 2. | Detuned MIC | 2. | Check MIC detecting current. If it |
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| is below normal value, MIC may |
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| have become detuned. MIC must |
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| be tuned. |
| 3. | Dirt on radiator face | 3. | Clean radiator surface. |
| 4. | Second trace rejection is | 4. | Disable the |
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| ON. |
| referring to paragraph 1.33. |
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Range changed but radar | 1. Defective RANGE key | 1. Try to hit [+] and | ||
picture does not change |
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| keys several times. If unsuccess- |
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| ful, replacement of keypad may |
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| be required. |
| 2. | SPU Board | 2. | Replace SPU Board. |
| 3. | Mother Board | 3. | Replace Mother Board. |
| 4. | Video lockup | 4. | Turn off and on radar. |
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