HP 4262A - Page 195

Section VIII
Figure 8-11
Model 4262A
Self Test Diagnostic Guide
Table 8-6 “Self Test Displays and Trouble Possibilities” is helpful in troubleshooting the
analog section. No pushbuttons except for the FUNCTION and TEST SIGNAL controls
should be depressed while the self test is being performed (if a pushbutton is inadvertently
pressed, the self test function will be reset and will require reactivating).
Table 8-6. Self Test Displays and Trouble Possibilities.
Display Source of FAIL signal Probable Cause of Trouble
FAIL 1 Process Amplifier has been saturated 1. One of the range resistor selection switches
by a signal of excessi_ve amplitude. on the A12 board is defective.
fiawarla tion Detector is generating SAT 2. One of the signal selection switches on the
gnat. A13 board is defective.
3. Saturation Detector on A13 board is faulty.
4. A13Q17 is always conducting ( display will
change to PASS when LOW LEVEL button
is pressed ).
FAIL 2 Integrator has developed an incorrect 1. Test signal is not present at Hcur terminal.
output voltage in an LCR measurement Al1 board is faulty.
le.
cycle 2. A12 range resistor amplifier is faulty.
3. An amplifier or an active switch on A13
board is faulty.
4. PLL circuit or Phase Selector in A14 board
is faulty.
5. Phase Detector or Integrator on A14 board
is faulty.
6. Auto Phase Adjustment malfunctioning.
7. Integrator Offset Null control malfunctioning
FAIL 3 Integrator has developed an incorrect
output voltage in the D/Q measure- A23 Processor and ROM board assembly )
ment cycle. is faulty.
Note: The trouble possibilities outlined in the table above presupposes that the digital
control section is operating correctly. A FAIL indication can also be generated
by trouble in the digital section.
8-22
Figure 8-11. Self Test Function (sheet 2 of 2).