TM8400B-L-00
1 November 2004
Step 15. Connect scope to TP4 w.r.t. TP3. Set temperature to 24°C. Switch
function switch to STANDBY position. Should be 0.75 ±0.03 volt peak
to peak square wave. Turn Function Switch to ZERO.
Step 16. Connect scope to TP9. Should be <±5 mV.
Step 17. Set Function Switch to STANDBY. TP9 should be less than 1 volts
square wave.
Step 18. Connect scope to TP8. Should be between 0 V DC and -5 V DC.
11.4.3. METER CALIBRATION
Step 1. With Function switch to zero position meter display should read
approximately zero. The offset (if any) is from the conductivity board and
will disappear after conductivity board is calibrated in Section 3.4.4 step
1.
Step 2. Connect frequency counter to TP11 (on Meter PCB 16504) and measure
clock frequency. Frequency should be 120 kHz ±.5 kHz for 60 Hz line
frequency, or 125 kHz ±.5 kHz for 50 Hz line frequency. Adjust R306 if
necessary.
Step 3. Depress and hold test switch (S301) on meter circuit board. (This switch
disconnects reference and signal inputs from conductivity board and
connects meter reference and signal inputs to an on board voltage. By
resistive division signal voltage is 20% of reference voltage). The display
should read XX2000 ±0002 digits with instability of ±0001 digits. Adjust
R309 if necessary to obtain correct reading. Release Test switch.
11.4.4. MATCHING AND BALANCING
NOTE: The following steps for balance, zero and gain adjustments assume that the
proper matching resistor R203 has been installed for the conductivity cell in use.
Step 1. Connect a 0.1 /step decade box in place of the conductivity cell.
Connect a 500 resistor, 4.7 f capacitor and two switches shown in
Figure 11.1 in series with the High Current (C1) lead to the decade box.
Set the decade box for 500 , close S1 and open S2. Turn the Autosal
Function Switch to READ and set the Suppression Switch for a reading of
less than XX+9999.
Open S1 and adjust R213 on the Conductivity PCB 18961 until no change
is indicated by the display when the 470 resistor is switched in and out
To Next Page
Loading...