TM8400B-L-00
1 November 2004
11.4.2. CONDUCTIVITY PCB CHECK
Step 1. Turn power OFF.
Step 2. Turn Function Switch to zero.
Step 3a. Switch power ON.
Step 3b. Use the positive lead of C208 as the ground reference for the following
steps unless otherwise stated.
Step 4. Check +15 V DC (at R222 right lead), -15 V DC (at R241 left lead), +7.5
V DC (at R222 left lead), -7.5 V DC (at R241 right lead).
+15 V supply can be adjusted with R211, -l5 V supply can be adjusted
with R212. 15 V supplies should be within ±0.01 V and 7.5 V supplies
should be within the range 7.5 V to 8.5 V.
Step 5. Connect scope to TP14. Adjust R257 for a frequency of approximately
150 Hz for 60 Hz line power operation.
NOTE: If 50 Hz line power operation is required the oscillator
frequency may have to be changed to approximately 175 Hz to
eliminate beating with the line which causes the instrument to be
slightly unstable. Changing the frequency may be done by adjusting
R257.
Step 6. Connect a dual beam scope to TP13 and TP14. Check that TP13 overlaps
TP14 by at least 100 s (See Figure 9.1).
Step 7. Connect a dual beam scope to TP11 and TP12. Waveforms should appear
in same phasing to TP13 and TP14 as shown on Figure 9.1.
Step 8. Connect DVM to TP6. Should be +10.00 V DC ±0.03 V DC.
Step 9. Connect DVM to TP10. Should be -10.00 V DC ±0.03 V DC.
Step 10. Connect scope to TP5. Should be 1.82 ±0.02 volt square wave.
Step 11. Connect scope to TP7. Should be <±5 mV.
Step 12. Connect scope to TP2. Should be <±0.2 mV.
Step 13. Connect scope to TP1. Should be 0.73 ±0.01 volt square wave.
Step 14. Connect scope to TP4 w.r.t. TP3. Turn Function Switch to ZERO position.
Should be <±5 mV.
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