Foxconn 7870 manual Troubleshooting, Problem Possible Cause

4 Troubleshooting

The 7870D Interfacility Link unit was tested before it left the factory. However if you are experiencing difficulties see the list below for possible solutions. if you are still experiencing problems, attempt to isolate and identify the malfunctioning unit before consulting Foxcom’s technical support.

Table 8 Troubleshooting the Transmitter

Problem		Possible Cause
1.	Laser LED not on	a. No DC power to the unit. Possible
		power supply problem or AC power
		input problem. Check the power
		supply fuse.
		b. Verify LSRI monitor is between -4.2
		and -4.8VDC. If not, laser may have
		overheated. Disconnect power or
		remove plug and allow to cool. Try
		again with better airflow.
		c. If an optical power meter is avail-
		able, measure the optical power out
		of the transmitter. The power
		should between 0.5 mW[-3 dBm]. If
		an optical power meter is not avail-
		able, use another receiver to deter-
		mine if there is optical power
		emerging from the transmitter (use
		a 5 meter jumper cable). If there is
		no optical power, then the transmit-
		ter unit is malfunctioning.
		If any or all the above are not within
		the guidelines, the transmitter unit is
		faulty.
2. The RF LED is not		The input signal is less than -28 dBm;
	lit	verify RF signal strength [RSSI] is≤0.2
		VDC. [See Table 4 7870T Transmitter
		Pinout on page 20]. Even if slightly out
		of range, the unit may still function,
		although it will register an alarm
		condition.
3.	RF LED illuminated	Unit may be receiving stray RF “pick
	- with no input	up”. Solution: provide RF input or use
	signal	necessary termination input.`

7870 Interfacility Link Installation and User’s Guide	page 25
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