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Service Addendum14
No Display Troubleshooting
"No Display"
Start
Turn on the supply and try to program it from the
front panel. While measuring the voltage at the
output terminals, program the voltage and current to
full scale. Toggle the ON/OFF key while observing
the external voltmeter.
No display but output
OK
?
Check the A2 GPIB board, bias circuits,
PCLR (test points 1 - 4 Table 6-3) and
cable W9
No
Turn off supply, remove front panel
assembly to access circuits on the A3 front
panel board. Turn on the supply.
Check 5V bias at R1-6, display voltages:
1.1V at R1-14, 2.2V at R1-2 and 3.3V at
R1-16 (meter common at R1-3). See Fig.
6-4.
Display and bias
voltages OK
?
Check A3C1,
A3R1 and A3RT1.
No
Check 10MHz Clock signal at
A3J2-9. See Fig. 6-9.
Yes
Display and bias
voltages OK
?
Check A3Y1,
A3C3, A3C4 and
A3U3.
No
Yes
Program voltage and current fron the front
panel. Measure the voltage at the output
terminals. In case the output is disabled
press the output ON/OFF key while
observing the output with an external
voltmeter.
Yes
Output Voltage present
?
A3U3, A3U4 or A3U8
defective. Perform
front panel SA. See
Table 3-4.
LCD or cable W19 defective.
No
Yes
Figure 3-5. No Display Troubleshooting