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4-2
SECTION 4 – TROUBLESHOOTING GUIDE
Faulty Timer
Faulty SCR/Voltage Regulator
Module
Faulty Speed Control Board
the cable. The peak-to-peak voltage should be at least
0.4 V and may be as high as 3 to 5 V depending on the
motor speed. If the voltage is too low or not present, the
possible causes are:
Open or shorted cable
Failed transducer
Transducer is not positioned properly
Check the resistance between the two pins in the
transducer connector. If the resistance is less than 200
ohms, the transducer may be good. Note that the 3065
Wettability Tester requires a very small clearance between
the transducer and the gears for proper operation. If the
resistance is greater than 200 ohms, there may be a
broken wire or the transducer may be damaged. Contact
Factory for assistance.
The timer normally has closed contacts at terminals 1 and
4. Terminal 1 is ground. When the timer is off, terminal
4 is also grounded. When the timer is on, terminal 4 will
have a DC voltage between 0 and 15 vdc depending on
the speed setting of the mixer.
If the SCR/Voltage Regulator module is suspected to be
faulty, check the fuse under the SCR/Voltage Regulator.
Replace it if it has failed. If fuse fails repeatedly, the
SCR/Voltage Regulator may be bad. If fuse is OK,
proceed as follows:
1. Set the VARIABLE SPEED control knob to its full
counterclockwise position. The motor will not turn or
turn very slowly (less than 100 RPM). Slowly rotate the
control clockwise. After the control is rotated about 30
degrees, the motor will start turning. The motor speed
should be smooth at speeds less than 3000 RPM. As the
VARIABLE SPEED control knob is turned, the motor
speed should increase smoothly and continuously from
less than 3000 RPM to greater than 16,000 RPM as the
control is rotated.
2. If the motor does not rotate or change speed
smoothly, the VARIABLE SPEED control potentiometer
or the SCR/Voltage Regulator is faulty.
Eliminate all other possible sources of the problem before
replacing the speed control board. If the problem
persists, replace the speed control board.
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