Hitachi S-4800 manual Troubleshooting, Symptom Cause Countermeasure

4.2.3 Troubleshooting

Symptom	Cause	Countermeasure
Pump does not rotate at all.	Power failure or voltage drop	Check the power supply.
The breaker switches off	below 90 V.
immediately. When turning
	Oil highly viscous because the	Close the suction port and turn
on the switch, pump buzzes
	ambient temperature is low (below	the switch on and off repeatedly
and does not start.
	9 °C).	to repeat slight rotation or warm
		the pump externally.
Vacuum degree cannot be	Air is leaking due to defective	Check for a leaky point and
enhanced.	vacuum piping.	repair as required.
	The inside of vacuum pipe is	Degas the pipe.
	contaminated.
	Pipe is too thin or too long.	Maximize the inner diameter of
		pipe and minimize its length.
	Oil is deteriorated.	Replace oil.
Loud noise is emitted.	Oil is inadequate.	Add oil.
	Air is leaking through the	Repair the leaky point.
	upstream pipe.
	∗ Abnormal sound may occur for approx. 5 to 6 sec at start of
	evacuation, but this does not indicate a fault.
Oil is leaking.	Oil is leaking through the drain	Make sure the drain valve is
	valve (for VR16L).	closed. If oil leaks through the
		valve is closed, replacement
		with a new valve is required.
	Oil is leaking through the drain	Retighten the plug. If oil still
	plug (for VR16L-K/N).	leaks, replace the drain packing.
	Oil splashes through the exhaust	Adjust oil level of replace the oil
	port.	mist trap (element).
Pump vibrates abnormally.	Oil is highly viscous due to low	Warm the pump externally.
	ambient temperature (below 9°C).

NOTICE: If the trouble cannot be remedied by the above procedures, contact your dealer, because overhaul, cleaning or repair may be required at the specified service shop.

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