Visual Fault Locator (VFL) - DTX Compact OTDR Module

Locating Fibers and Faults with the Visual Fault Locator (VFL)
The DTX Compact OTDR modules include a visual fault locator that helps you do the following:

  • Quickly check fiber continuity. Trace fibers to determine the polarity of duplex connections and identify connections between patch panels.
  • Locate breaks and bad splices. These faults scatter the locator’s light, causing a red glow in the affected area.
  • Reveal high-loss bends. If the locator’s light is visible around a bend in a fiber, the bend is too sharp.
  • Reveal problems in connectors. A damaged fiber inside a connector causes a red glow in the connector.
  • Optimize mechanical splices and pre-polished connectors: Before sealing the splice or connector, adjust the fiber alignment for minimal glow where the fibers meet. (Follow the manufacturer’s assembly instructions for splices and connectors.)

Using the Visual Fault Locator
The visual fault locator port accepts connectors with 2.5 mm ferrules (SC, ST, or FC). To connect to other ferrule sizes, use a patch cord with the appropriate connector at one end and a SC, ST, or FC connector at the tester end.

To use the visual fault locator:

  1. Clean the connectors on the patch cord, if used, and the fiber to be tested.
  2. Connect the fiber directly to the tester’s VFL port or connect using the patch cord.
  3. Turn on the visual fault locator (refer to Figure 1):
    • DTX-MFM2/SFM2/GFM2 module:
      • Press the button near the VFL connector.
      • Press again to switch to flashing mode.
      • Press again to turn off the locator.
    • DTX Compact OTDR module (refer to Figure 1):
      • Turn the rotary switch to SINGLE TEST.
      • If necessary, press F1 Change Media then set the media type to Fiber OTDR.
      • Use the softkeys to start the VFL, switch to pulse mode, and stop the VFL.
  4. Look for the red light to locate fibers or faults, as shown in Figure 1.
  5. View the VFL’s light indirectly by holding a white card or paper in front of the fiber connector emitting the light.

    The locator’s light may not be visible through dark-colored fiber jackets.

Figure 1

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