Cleveland Motion Controls ULTRA ISC CANTILEVER TRANSDUCER CLTSCM REV AA - Manual (Page 19)

MAN-70445-0 R EV AA U LTRA S ERIES ISC C ANTILEVER T RANSDUCER T ECHNICAL M ANUAL
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analog signal from an internal op-amp (operational amplifier) buffer stage. The BLK wire has the signal return and
the WHT wire is the amplifier output. Resistive loads drawing up to 5 mA of current are allowable.
One of the most common ways of reversing the sense of the load cell signal is to invert the mechanical orientation of
the load cell body itself. If this is impractical, it is possible to interchange the BLK and WHT signal wires, as the load
cell amplifier and output stage is essentially floating with respect to the 24 VDC supply ground. Note however that
the voltage potential cannot be allowed to float “unbounded”, and that connection to line potential drive circuits is not
permissible (and potentially hazardous).
2.5 P OTENTIOMETERS A DJUSTMENTS (I F N EEDED )
The gain and zero adjustments are factory preset but accessible by the user for adjustment if absolutely
necessary. Adjustment holes to access these potentiometers are visible on the side of the housing. Adjustments can be
made by removing the sticker cover around the amplifier enclosure. Refer to Figure 3 to locate the zero and gain
adjustment holes.
Table C lists these potentiometers, their reference designator, and a description of their functions. For information on
the correct adjustment tool to use, refer to section 2.5.1 in this document.
Potentiometer
Reference
Designator
Function
GAIN P2
This potentiometer is preset but accessible by the user for adjustment if
absolutely necessary. It provides a 10:1 “vernier” adjustment of the amplifier
gain. It is a multi-turn potentiometer, with clockwise rotation causing an
increase in amplifier gain. When turned fully counter clockwise, the
potentiometer causes the amplifier stage to provide the minimum gain.
ZERO P1
This potentiometer is preset but accessible by the user for adjustment if
absolutely necessary. It provides a zero (offset) adjustment. It is a multi-
turn potentiometer, with clockwise rotation causing a positive shift in the
analog outputs. It should be set mid-way prior to setting the ZERO
adjustment.
Table C Potentiometer Adjustments
2.5.1C ORRECT A DJUSTMENT T OOLS
A small flat-bladed “jeweler’s” screwdriver is required. The overall diameter should be no larger than 0.062” The
thickness of the blade flat should be no greater than 0.012”. Ideally, a non-conductive tool (plastic or ceramic)
provides the safest approach by minimizing the generation of minute metallic shards that are made when a metal blade
accidentally scuffs the aluminum housing.
The Zero is normally adjusted first while the load cell is in the No-Load condition (i.e. with no tension in the web).
The calibration forces are then applied to the transducer and then the Gain potentiometer adjusted to achieve the
desired scale factor. It is advisable to look for a particular step change between load and no-load conditions and adjust
the step size independent of a particular zero point. Only after the desired scale factor is achieved, is it then best to
adjust the final zero point using the Zero adjustment.
Following adjustment, it is important to seal the adjustment holes for continued protection from contamination. A
small piece of adhesive backed tape can be used to reseal.