2002 by ELTRA GmbH Germany – January 2002 – Service Manual OH 900 / ON 900 / ONH 2000
1.1-2
Touch the rectifier ( 1 ) of the IR-cell, it should feel warm ( about 45°C ).
( The analyser does not need to be turned off, nor must the infrared rack be removed ).
If the rectifier is cold ( room temperature ), you should check the IR-source voltage,
see 2. 4 .
If there is no IR source voltage, replace the power supply, see 3. 4
If there is IR source voltage, but the rectifier ( 1 ) is cold, then the IR source is
defective.
Since the IR sources are connected in series, the rectifier is cold, even when just one
of the IR sources is defective.
Open the infrared rack, remove the IR source ( see 3.2 ), and identify the defective
part by resistive measurement.
Non defective IR sources have a resistance of only 1 Ohm, while defective ones have
a much higher or unmeasurable resistance.
CAUTION!
When setting new IR sources, CO2 can be produced during the first warming up.
Therefore, all points of the adjustment instructions ( see 2.3 ) should be carefully followed
through.
If the rectifier ( 1 ) is warm, then check if the chopper motor is at a standstill. To do
this, an IR path must be unscrewed.
Through the bore holes in the chopper motor housing, the chopper blades should be
be visibly rotating.
The cause for a chopper motor that doesn't run are usually the springs ( see 3. 5 ) that
were built in before September 1993 .
Exchange the spring-type for a newer type. The motor itself should turn anyway, even
when the chopper blade is not mounted. If not, the motor is defective.
Theoretically, the circuit board IR21 may also be at issue. This is, however, very
unlikely if more than one channel is not functioning in a multi-channel device.
P1
06421 IR13
I R 1 3 0 6 4 2 0
1
1 - 1 - 2
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