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| Figure 12: | |
10.2 Video Signal |
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| Problem |
| Remedy |
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| No video at the output | 1. | Confirm that your source and output devices are powered on and |
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| connected properly. The input of your machine should be of an identical |
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| signal format at the output of your source. Signals at the output of your |
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| machine should be of an identical signal format as at the input of your |
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| display. |
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| 2. | Confirm that any other device in the signal path have the proper input |
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| and/or output selected. |
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| 3. | Use the Video Tester to help trace faulty cables and equipment (see |
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| section 4.1). |
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| Video level is too high or | 1. | Verify that the lines are well matched through 75ohm impedance; |
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| too dim. |
| otherwise it results in a video level that is too high or too dim. |
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| 2. | Confirm that the connecting cables are of high quality and properly |
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| inserted. |
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| 3. | Check level controls located on your source input device or output display. |
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| Noise bars are "rolling" |
| Hum bars (ground loop) are caused by a difference in the ground potential of |
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| up or down in the output |
| any two or more devices connected to your signal path. This difference is |
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| image |
| compensated by passing that voltage difference through any available |
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| or: |
| interconnection, including your cables. |
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| WARNING! |
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| Low Frequency Hum in |
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| Do not disconnect the ground from any |
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| the output signal |
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| piece of equipment in your signal path! |
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| Check the following to remove hum bars: |
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| 1. | Confirm that all interconnected equipment is connected to the same phase |
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| of power, if possible. |
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| 2. | Remove equipment connected to that phase that may introduce noise, such |
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| as motors, generators, etc. |
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| 3. | Disconnect all interconnecting cables and reconnect them one at a time |
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| until the ground loop reappears. Disconnect the affected cable and replace, |
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| or insert an isolation transformer in the signal path. |
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| 4. | Use a video Isolator, such as Kramer |
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| such as Kramer 123V inserted in the video signal path. |
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Kramer Electronics Ltd. |
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