Tuttnauer 3850 ELVG-D, Technician Manual

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6.9 Inlet key does not let water into the chamber
♦
Check if this key is faulty. If it beeps when pressed it is O.K. if not,
replace the keypad. If this does not help, replace the complete
PREDG and keypad unit.
♦
Check the float at the water reservoir by manipulating it using a
screwdriver or a tool and repair/replace it. If the float is
functioning, the problem could be with the control circuit at the
PREDG board: the test board between TP1 (GND) and TP10 (water
valve): GOOD = 0.0V to 0.05V.
♦
If the control is OK, there may be a problem with the valve itself or
with its connector.
♦
Check and replace the coil if necessary.
6.10 Pressure stays close to 100 kPa (0 psi), temperature does not exceed
110 - 115
°
C (207
°
F) or, water inlet lasts a longer time than usual
This phenomenon is most likely due to malfunction of the air valve. The
air valve’s normal operation is as follows:
OPEN whilst turning the system on, OPEN throughout WATER INLET
and HEAT until temperature has reached 90
°
C or 194
°
F, CLOSED from
that stage on, and OPEN during DRY.
The valve’s control on the AJUNC3 board should act as follows:
0.0V = valve OPEN
5.0V = valve CLOSED
If the problem lies on the AJUNC 3 board it should be replaced. It is
recommended to replace both the AJUNC3 and the solenoid because a
damaged solenoid may affect the AJUNC3 board. If the control circuit
on the AJUNC3 is OK, the problem is probably with the PREDG board.
6.11 Heaters are always ON or OFF
Warning: If you need to tighten a screw, make sure to do so only when
the power cord is disconnected.
♦
Check the heaters connections.
♦
Check the cutoff thermostat position and turn it clockwise to the end.
♦
Check the control at TP1 and TP12 for ON = 0.0V, OFF = 5v
♦
Check connections between AJUNC3 to SSR at TP4.
♦
Does AC voltage enter the SSR at AC connector and SSR pin 2?
♦
Is SSR output the AC voltage? Check AC connector and at SSR pin 1.
♦
Is the control OK? Check the SSR for 5.0V between pins 3&4. If
control is OK, but SSR output is not the AC voltage, replace the
SSR.
6.12 Heaters o.k. but autoclave does not reach sterilization temperature
♦
Check and calibrate the cutoff position.
♦
Check and clean/ replace leakage at the exhaust valve.
♦
It is also possible that there is a calibration variance, check the
GAIN pressure calibration, perhaps it should be lowered or, the
GAIN temperature should be increased.
♦
Another possibility is that insufficient water level in the chamber
does not allow the pressure to build up. Check the water level
detector electrode, or the leveling of the autoclave.