LG Electronics 120S user manual Output circuit troubles and corrective actions, 11-10

Chapter 11 Troubleshooting

11.4.2Output circuit troubles and corrective actions

The following describes possible troubles with input circuits, as well as their corrective actions.

Condition		Cause			Corrective Action
When the output is	yLoad is half-wave rectified inside (in some cases, it is true				y Connect registers of tens to hundreds KΩ across the
off, excessive	of a solenoid)				load in parallel.
voltage is applied to	yWhen the polarity of the power supply is as shown in ①,
the load.	C is charged. When the polarity is as shown in			②, the
	voltage charged in C plus the line voltage are applied				R
	across D. Max. voltage is approx. 2√2.					D
	C	D			C			~
			~		R	Load
	R
		Load
	*) If a resistor is used in this way, it does not pose a
	problem to the output element. But it may make the
	performance of the diode (D), which is built in the load,
	drop to cause problems.
The load doesn’t	y Leakage current by surge absorbing circuit, which is				y Connect C and R across the load, which are of registers
turn off.	connected to output element in parallel.				of tens KΩ. When the wiring distance from the output
	Output				module to the load is long, there may be a leakage current
		Load			due to the line capacity.
	C	Leakage current		~	R	C	R
	R
					Load	Load
When the load is	y Leakage current by surge absorbing circuit, which is				y Drive the relay using a contact and drive the C-R type
C-R type timer, time	connected to output element in parallel.				timer using the since contact.
constant fluctuates.	Output				y Use other timer than the C−R contact some timers have
					half-ware rectified internal circuits therefore, be cautious.
		Load
	C
			~			T Timer
	R	Leakage current
					Output	X		~
The load does not	y Sneak current due to the use of two different power				y Use only one power supply.
turn off.	supplies.				y Connect a sneak current prevention diode.
	Output				Output
		Load			Load
		E2		E1			E	E
					If the load is the relay, etc, connect a counter-electromotive
	E1<E2, sneaks. E1 is off (E2 is on), sneaks.				voltage absorbing code as shown by the dot line.

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