TB 9-6695-298-35
(19) The voltage measured in (18) above should equal the voltage calculated in (17)
above; if not, perform b(6) below. Record this voltage to 4 decimal places.
(20) Set the MODE switch to STATIC. Press and release 0 key. The message
Enter Cal Mode Num! should be displayed.
(21) Press 2 key to ground the input of the amplifier.
A flashing C will be
displayed. This indicates that the calibration mode is active.
(22) Repeatedly press and release the down arrow key until the displayed units
are Unc Avg.
(23) Display will flicker between 0; if not, perform b(7) below.
(24) With the digital multimeter measure the voltage between AGND (fig. 1) and
jumper R9 (fig. 1) by connecting the + (positive) lead to jumper R9 and the - (negative)
lead to the AGND pad. This voltage should be close to 0 V do. Record this voltage.
(25) With the digital multimeter measure the voltage between U8 (fig. 1) pin 5 and
AGND (fig. 1) by connecting the + (positive) lead to U8 pin 5 and the - (negative) lead to
the AGND pad.
(26) Digital multimeter will indicate the same voltage as measured in (24) above; if
not, perform b(8) below.
(28) Press 0 key to activate the calibration mode; the message Enter Cal Mode
Num! should be displayed.
(29) Press 5 key to read the strain gage simulator input signal. A flashing C
should be displayed in the leftmost display segment. This indicates the calibration mode
is active.
(30) Set the strain gage simulator to 0 percent and the polarity switch to the +
(positive) position.
(31) Press the ZERO pushbutton to perform an auto gain/auto zero.
(32) Select the Unc Avg display units.
(33) Set the MODE switch for STATIC.
(34) Set the strain gage simulator to +100 percent. Record the reading on the TI;
the reading should be approximately 25,835.
(35) Set the strain gage simulator polarity switch to the - (negative) position.
Record the reading on the TI; the reading should be approximately -25,835.
(36) Multiply each of these readings by 0.0425 and record these numbers as +D.R.
and -D.R. Set strain gage simulator to 0%.
(37) Set the MODE switch to DYNAMIC. Set strain gage simulator to 100%.
(38) Adjust R16 (fig. 1) to obtain the -D.R. value.
(39) Set the strain gage simulator polarity switch to the + (positive) position.
(40) Adjust R15 (fig. 1) to obtain the +D.R. value.
CHANGE 1 11