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Component Replacement
Disconnect electrical power supply before opening or working inside the sampler controller enclosure .
Timing Components
The timer is a solid state module and non-repairable . If the controller fails to function, first determine if the problem is
electrical . If electrical, check for power supply ON, and for continuity through ON/OFF switch .
Cycle Timer
If the sampler controller fails to function at any setting of load dial, the timer probably needs to be replaced .
Replacement timers are available from Sentry Equipment Corp . Follow the controller circuit diagram to properly
connect a replacement timer .
A 1/4-inch nut is used to hold the timer in place against a rubber base sheet . The nut is self-locking and should be tightened
only until the timer is secure . DO NOT OVERTIGHTEN as this could cause the timer case to crack and allow damaging
moisture inside .
Any time connections are removed from the timing module for any reason, always refer to the circuit diagram when
reconnecting wires to timer terminals .
Controller Sample Rate Potentiometer
The controller sample rate potentiometer is a round component with brown wire leads on two of three lugs . If
controller operation becomes erratic (e .g ., cycles at some load size dial settings but not at others, or different sampling
rates at the same setting), the potentiometer is the probable cause . It is not repairable and must be replaced .
Replacement parts are available from Sentry Equipment Corp .
To replace:
1. Unplug the two brown wire leads from insulated terminals on the timer module .
2. Release the two set screws in the black knob and remove the knob .
3. Remove the rubber seal hex nut on the potentiometer shaft and on the ON/OFF switch toggle, both from outside
of the controller .
4. Inside the controller, remove the subplate holding switch, autofuse and potentiometer .
5. Remove the hex nut and lockwasher holding the potentiometer to the subplate . Remove the potentiometer .
6. Insert the replacement potentiometer shaft through the subplate . Rotate until the tang enters the slot on the
subplate . Attach it with the lockwasher and hex nut .
7. Reassemble the subplate through the holes in the controller cover . Install the rubber seal hex nuts on the
potentiometer and switch .
8. Reconnect the potentiometer lead wire terminals to yellow and brown insulated timer leads .
9. Reassemble the controller cover into box .
ISOLOK MSA Sampler
15
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