Fiber Optic Design Guide - Maite y Mario

Troubleshooting
Commercially available test equipment such as Blonder Tongue’s FOTK Fiber Optic Troubleshooting Kit are effective
tools for locating problems with the fiber optic cables. The FOTK can also be used to verify that the transmitter is
indeed putting out light. Other common problems include using a transmitter as a receiver and vice versa, lack of continuity
in the optical fiber, lack of power (or reverse power), or improper input levels. The transmitter is optimized to
accept a 1-Volt sync-to-white input signal. Larger inputs will introduce nonlinearities or interfere with function. Note
that the transmitters and receivers are designed to work with a 75 Ohm system. If problems persist contact the factory.
Problem/LED Status Check Comments
No optical power out of Tx. Check Tx power connection and polarity If there are less than +12 Volts between pins
Green “Power” LED is not lit. J1-1 and J1-2, a higher current power supply
is required (at least 200mA). If the voltage
on pin J1-1 is negative with respect to the
voltage on pin J1-2, reverse the power supply
leads.
No optical power at the Rx. Check power at the Tx If there is power present at the Tx, verify the
Rx “LOS” LED is red. proper fiber is connected to the Rx. If the
proper fiber is connected, ensure the integrity
of the fiber.
Signal out of Rx is noisy. Check optical power at Rx For this link to work properly, the minimum
Rx “LOS” LED is red. required input power must be received. See
Table 2 to get the minimum input power
required for the product purchased* Be sure
to ground the case of the transmitter and
receiver.
No signal out of Rx Check the Rx power connection and polarity If there are less than +12 Volts between pins
Rx “LOS” LED is off. J1-1 and J1-2, a higher current power supply
is required (at least 135 mA). If the voltage
on pin J1-1 is negative with respect to the
voltage on pin J1-2, reverse the power supply
leads.
Signal out of Rx is distorted. Verify the input signal at the Tx Must be 1-Volt sync-to-white or less. Larger
Rx “LOS” LED is off. signal will cause distortion.
Verify fiber size Fiber must be 62.5/125µm for multimode
models. Larger core fibers may overload
receiver. Verify that Rx power is within specifications.
*NOTE: 850 nm video systems generally are bandwidth limited at distances over 1.5 km. When this occurs, the Rx output will not be
usable even when sufficient optical power is received.
LABORATORIES, INC.
The Standard of Quality in TV Signal Distribution
Section 2
43
One Jake Brown Road, P.O. Box 1000
Old Bridge, NJ 08857-1000 USA
(800) 523-6049 • (732) 679-4000 • FAX: (732) 679-4353
www.blondertongue.com