Troubleshooting Charts; Troubleshooting Test Points; Bias And Reference Supplies - Agilent Technologies 668xA Service Manual

Troubleshooting Charts

Figure 3-1 gives overall troubleshooting procedures to isolate the fault to a circuit board or particular circuit (see Figure
3-20 for the location of the circuit boards). These procedures include the use of power-on selftest (Table 3-2) and signature
analysis techniques (Table 3-5 through Table 3-7). Some results of Figure 3-1 lead to more detailed troubleshooting charts
that guide you to specific components. The troubleshooting charts are organized as follows:
Chart
Figure 3-1
Figure 3-2
Figure 3-3
Figure 3-4
Figure 3-5
Figure 3-6
Figure 3-7
Figure 3-8
Figure 3-9
Figure 3-10
Figure 3-11
Figure 3-12

Troubleshooting Test Points

The troubleshooting charts reference test points listed in Table 6-3 of Chapter 6. Test points are identified by an encircled
number (such as U in schematic diagrams and component location drawings, also in Chapter 6).

Bias and Reference Supplies

Many of the following troubleshooting procedures begin by checking the bias and/or reference voltages. Table 6-3 lists the
test points for these voltages and gives the correct reading for each. The circuit board component location diagrams identify
these points on each board.
34 Troubleshooting
Overall procedure checks selftest errors, calibration errors, ac input circuit, fan, readback
circuits, A10 Control Board, GPIB cable, digital port, serial link, rotary controls, current
amplifier.
No display (from Figure 3-1).
OV circuit not firing (from Figure 3-1).
OV circuit is on at turn on (from Figure 3-1).
Output level is held low (from Figure 3-1).
Output level is held high (from Figure 3-1).
DAC circuits (from Figure 3-1).
DAC test waveforms.
CV and CC DAC and amplifiers (from Figure 3-1).
Serial Down circuit (from Figure 3-1).
Secondary interface circuit (from Figure 3-1).
Slow downprogramming circuit (from Figure 3-1).
Trouble or Circuit