ENMET ISA-40M - Manual (Page 14)

ENMET Corporation ISA-40M Oxygen Monitor
12
1. Null adjust:
a) Disconnect the oxygen cell from the circuit by disconnecting leads at TB1 or TB2 as shown below:
Channel Disconnect Terminal Positions
1 TB1 – 1 O2 (+) and TB1 – 1 O2 (–)
2 TB1 – 2 O2 (+) and TB1 – 2 O2 (–)
3 TB2 – 3 O2 (+) and TB2 – 3 O2 (–)
4 TB2 – 4 O2 (+) and TB2 – 4 O2 (–)
b) Check the null voltage for the channel. Connect the voltmeter leads to the appropriate test points, shown below:
Channel Test points On Circuit Board
1 TP101 (–), TP102 (+) For channel(s) 1 (and 2)
2 TP201 (–), TP202 (+) For channels 1 and 2
3 TP101 (–), TP102 (+) For channel(s) 3 (and 4)
4 TP201 (–), TP202 (+) For channels 3 and 4
c) Adjust the appropriate null adjust potentiometer, shown below, so the voltage between the points is 0.00 V DC :
Channel Potentiometer On Circuit Board
1 R108 For channel(s) 1 (and 2)
2 R208 For channels 1 and 2
3 R108 For channel(s) 3 (and 4)
4 R208 For channels 3 and 4
2. Low Level Set Adjust:
a) Reconnect the oxygen cell by reconnecting the leads removed in step 2 a).
b) Make sure the oxygen cell is properly connected by measuring the voltage between the cell leads; this voltage
must be between 0.043 and 0.09 V DC .
c) Measure the Low Level Set voltage for the channel by connecting the voltmeter leads to the appropriate test
points, shown below:
Channel Test point On Circuit Board
1 TP101 (–), TP103 (+) For channel(s) 1 (and 2)
2 TP201 (–), TP203 (+) For channels 1 and 2
3 TP101 (–), TP103 (+) For channel(s) 3 (and 4)
4 TP201 (–), TP203 (+) For channels 3 and 4
d) Adjust appropriate low level set potentiometer, R112 or R212, so the voltage between the test points is 1.03 V DC .
Channel Potentiometer On Circuit Board
1 R112 For channel(s) 1 (and 2)
2 R212 For channels 1 and 2
3 R112 For channel(s) 3 (and 4)
4 R212 For channels 3 and 4
3. Full Scale Adjustment:
a) Place voltmeter leads at the appropriate positions, shown below, to adjust the full scale voltage:
Channel Test point On Circuit Board
1 TP101 (–), TP102 (+) For channel(s) 1 (and 2)
2 TP201 (–), TP202 (+) For channels 1 and 2
3 TP101 (–), TP102 (+) For channel(s) 3 (and 4)
4 TP201 (–), TP202 (+) For channels 3 and 4
b) Adjust the appropriate oxygen gain potentiometer on the front panel of the control unit so the voltage between
the test points is 1.55 V DC .