41
1.
The filament may not be centered over the air jet. Follow the procedure “Testing the
position” in the Heating filament replacement section of the Maintenance chapter.
2.
If the filament is correctly centered, then the tension in the two cables that transmit the
pulling force from the solenoid to the puller bars might not be equal. To check the tension
and adjust if necessary, first contact Sutter Instrument to discuss the details and then
follow the procedure “Pulley Adjustment” in the Maintenance chapter.
5.1.9
Problem: The shape and resistance of the pipette changes from pull to pull.
1.
In most cases, this is due to not using the midpoint velocity when making a patch pipette
or the program is unstable. See the Pipette Cookbook for recommended parameter
settings for your application.
2.
If the problem persists, then run the ramp test several times. If possible, use one long
piece of glass and move the glass over after each ramp test. If the ramp values are +/- 4
units or less the problem may be with the glass. If the values are greater than +/- 4 units
call Sutter Instruments.
5.2
Controller problems
5.2.1
Problem: The filament does not light up when pull is pressed.
There are a number of possible reasons why this might happen.
1.
Look and see if the filament has burned out. In some cases, it may be necessary to loosen
the screws holding the filament in place, as a very fine break may be hard to see.
2.
If the filament is OK, try running the ramp test and see what happens. If you have just
changed the filament, it is quite possible that the new filament needs a very different
HEAT value than what you have been using. It is always a good idea to run the ramp test
each time you change the filament.
3.
If you can run a ramp test but cannot pull a pipette when using the RAMP value for the
heat setting, there might be an air leak. Check to see if the air compressor is running
constantly. If so, try to locate the air leak. Check tubing, connections, air solenoid, and
the cap of the drierite canister. If the air compressor is not running, it is possible that the
air solenoid is stuck closed or the compressor has failed. Contact Sutter Instruments for
further instructions.
4.
If you run the ramp test and the HEAT value reaches 999 without the filament heating
up, check the tightness of the exposed connectors in the filament current pathway. These
are the filament-holding screws (the screws that hold the two brass jaws and the two nuts
connecting the filament wires to the posts behind the filament block).
5.
If these connectors are tight then the problem is probably the power FETs on the heat
sink. (Contact Sutter Instrument for further instructions.)
6.
If possible, run a ramp test and verify that the values on the display appear correct:
Double check that the pressure is set within the range of 200 – 500 and make sure that
the air time before the pull is set to 5 seconds; continue with Item 4 above. If the SRAM
memory chip battery is starting to fail, the pressure and/or the air time can be offset to
<0>, in which case the filament will not heat up during a pull. Upon finding these
conditions, contact Sutter Instrument Technical Support.
P-97 FLAMING/BROWN MICROPIPETTE PULLER OPERATION MANUAL – REV. 2.43 - DOM (20161118)
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