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8.2.3 Failure of the heating for steam generator ___________________________________________
In this case, the feed water pump runs only once
after the start of the program.
Fault diagnosis:
If the autoclave does not build up any pressure while
lamp "RUNNING" is blinking and the steam
generator under the chamber does not get warm, a
fuse has failed or a contact or the electronic CPU-
board is defective.
Call for a service engineer.
Check output of steam generator, fuse and steam
generator itself.
Fault correction:
Replace defective element. In case of defective
fuse, check the output of the electronic. The
semiconductor relay should only operate when the
exit is directed (e.g. by test knob). You can observe
its operation by the light of the respective LED of
output on the electronic circuit. Otherwise, the relay
is defective and the electronic must be replaced.
8.2.4 Short circuit of the temperature sensor for steam ____________________________________
In this case, the feed water pump runs only once
after the start of the program.
Fault diagnosis:
The autoclave reaches a pressure of approximately
2.2 bar (sterilization), respectively 0.3-0.4 bar
(disinfection) within 1.5 to 3 minutes after a program
start and keeps the pressure constant, but indicates
fault No.
4 after 5.5 minutes. The thermometer
monitors a temperature of 135°C (105°C) which
means that the flow nozzle is clear.
Call for a service engineer.
Fault correction:
Check temperature sensor for steam (screwed into
the current channel of the chamber block from
underneath) and replace it.
8.2.5 Too small dose of water __________________________________________________________
In this case, the feed water pump runs several
times after the start of the program.
After a program start, the pump must get into action
and, in the required pumping time of 16 seconds,
about 150 ml of aqua dest/aqua dem must be raised
from water reservoir to the steam generator.
Fault diagnosis:
If this water dose is too small, the pump will start
again at release of the steam generator's overheat
protection and after the end of the real pumping
time. Thus, the correct supervision times for pressu-
re generation and killing may be exceeded.
You must notify the MELAG Customer Service
Department.
To check the amount of raised water, loosen the
hose connection from pump to chamber block at the
chamber block, put the hose's end into a measuring
beaker and start the pre-warmed apparatus. After
16 seconds, the pump must stop with an amount of
water in the beaker between 130 and 170 ml. After
this pumping time, immediately switch off the
autoclave, otherwise the pump will start again due to
overheat of the steam generator (in order to avoid
this during the test, you can remove a cable shoe of
the steam generator).
If there are deposits of scale on the top side of the
disassembled hose, then it is necessary to clean
both this hose as well as the steam generator. See
Section 8.2.7.
Fault correction:
1. If the feed water pump (47) does not start, then
the following must be checked: the fuse for the
output for the pump, the cable connections, the
thermalprotection element installed on the pump
(a bimetallic trip), and the pump itself if required.
2. When the amount of water is too small, loosen
silicone hose on the suction side of the pump and
look if water runs out freely.
If insufficient water runs out, or no water at all,
check to see if the hose is clogged (clogging can
perhaps take place in the water storage tank),
and /or change the water filter if required.
Finally, check to make sure that a sufficient
amount of water is being pumped.
3. If there is no blockage on the suction side of the
pump and the amount of raised water is too
small, the pump should be replaced.
4. If the water reservoir is empty, but the autoclave
indicates no lack of water, check all cables and
the pressure switch for level control, perhaps
replace them. The contact of this switch opens
when the minimum amount of water (250-300ml)
is in the reservoir.
