Tokyo Boeki Labmax 240, Service Manual

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Service Manual
Chapter 3
3‑31
2. Action (Refer to “ASSY-9-1/2, 2/2” for assembly drawing.)
When the stepping motor (17) rotates, this rotating motion is transferred to
heat blocks (6,7,10) through timing belt (18), pulley (16) and revolving plate (14).
Revolving plate (14) has a shade pin which shades home position sensor (15) light
at home position. This detects home position at initialization.
When home position is detected, rotary encoder (united with motor) is reset, and
the output shows zero.
During measurement, the following pitches are sent in one cycle.
And one pitch (one reaction cuvette) is advanced counterclockwise in excess
by the cycle.
- Motion A : 13 pitches
- Motion B : 21 pitches
- Motion C : 27 + 60 pitches
Total : 121 pitches (2 1 pitch)
Rotation angle of motor is counted by rotary encoder (united with motor), and
rotation angle of heat block is checked.
- If rotation angle exceeds the range of tolerance or rotation time exceeds
permissible time, system gives an alarm and emergency stop.
3. Temperature control
Temperature of heat block (10) is detected by two temperature sensors (9) fixed
to the side of heat block (10), and heater (11) is accurately controlled by PID
control of TCD PCB. (Heat block temperature : 37 plus-minus 0.1 Celsius
degrees)
As protecting function, thermostat (12) is installed to the lower part of heat
Block (7).
In case the temperature exceeds 70 Celsius degrees, electric current to heater
(11) is turned OFF.