Fluke 5220A, Instruction Manual

Page: 69 / 138

Maintenance
Troubleshooting
4
4-23
Table 4-6. Mainframe and Digital Section Troubleshooting Guide (cont.)
Step Instruction Yes No Go to
33 The mainframe and digital section are operational; the
transconductance amplifier (A5, A6, A7) is defective. Check out
and repair the transconductance amplifier using Table 4-7,
Analog Section Troubleshooting Guide. 16
34 Is OVERCURRENT LED lit? 35 36
35 Check the following and repair as required:
1. Open feedback loop, current shunt to A5 Preamplifier.
2. Overcurrent detector on A8 PCB.
3. Failure status logic on A10 PCB.
4. Defective A5 Preamplifier PCB.
36 Is OVERCOMPLIANCE LED lit? 37 38
37 Check the following and repair as required:
1. Overvoltage detector on A8 PCB.
2. Open loop on transconductance amplifier (A5, A6, A7
PCBs).
3. Failure status circuit on the A10 PCB.
4. Open load or open circuit between output amplifier and
output terminals.
16
38 Check timing logic on the A10 Logic PCB, and the level shifters
on the A8 Analog Control PCB. Repair as required. 16