Fluke 2180A - Manual (Page 39)

Table 4-4. 2180A Troubleshooting (cont)
2180A
STEP
NO.
ACTION
Go to the step
number given
for correct
response
YES NO
22 Check U13, Q27 and their associated components. Repair as required then resume at step 14.
23 Is the waveform at TP7 as shown in Figure 4-4 (Magnitude & Polarity varies with the input signal)? 30 29
24 Is there 6.2 Vdc at TP16? (Use TP1 as corhmon.) 26 25
25 Check the Reference Circuit providing an input at U4-3 from the divider R4, R5, R6, R7 and VR2. Repair as
required then resume at step 14.
26 Check from TP1 (analog ground) to U6-6 for 100 mV dc and for approximately 200 mV dc at U6-9.
27 Are both voltages present? 29 28
28 Check Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15and their associated components. Repair as required then
resume at step 14.
29 Check the RTD Input Module plus U5-1, Q19, Q21, Q22, and their associated components. Repair as required
then resume at step 14.
30 is the waveform at U5-7 as shown in Figure 4-4 (Magnitude & Polarity varies with the input signal)? 34 31
31 Check the operation of Q5, Q6, Q7, Q18, U5 and their associated components. If any defective components
are found, repair as required and resume at step 13. If none are found proceed to the next step.
32 Connect TP2 and TP6 with a jumper to lock the instrument in the Auto Zero period.
33 Check U5, U3, U2, Q4 and their associated components. This circuit should now function as a closed loop
amplifier. Repair as required. Remove the jumper between TP2 and TP6 and resume at step 14.
34 Does TP10 toggle between the high and low logic levels? 36 35
35 Check U1 and its associated components then resume at step 14.
36 Replace the microcomputer U9, then resume at step 14.
37 Troubleshooting of the 2180A is complete. Remove all test equipment, reconnect any cables removed and
close the instrument.
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