Technical data

22 Agilent 35670A Supplement
4 Service Guide
To troubleshoot display failures
Replace entire section
Use this test to isolate display failures to the A101 Display
assembly, A102 assembly, or the A17 CPU assembly
✔ Step 1. Check the power inverter assembly.
• Set the power switch to off (O).
• Remove the cable connected to P13 on the A17 assembly.
• Set the power switch to on (|)
• Measure voltage at P13 pin 1 on A17 assembly.
• If voltage is not +5Vdc the A17 board may be faulty.
• Set the power switch to off (O).
• Reconnect the cable to P13.
• Set the power switch to on (|).
• Measure voltage at A17 P13 pin 1.
• If voltage is not +5Vdc the power inverter assembly may be
faulty.
• If display backlight lamps do not light up, one or both of the
lamps may be faulty.
• If lamps are replaced and still do not light up, the power
inverter may be faulty.
✔ Step 2. Check the CPU signals on the Display assembly.
• Set the power switch to on (|).
• Using a logic probe check that the following TTL signals are
toggling:
• If the signals are incorrect the A17 board may be faulty.
Page in original guide 4-23
Test Location Signal Na m e In/O u t
P14-31 VSYNCLCD A17 Out
P14-33 HSYNCLCD A17 Out
P14-24 CLK_LCD A17 Out