Agilent Technologies 5517B Operation And Service Manual page 98

8-146. Warm-Up Error Amplifier Troubleshooting
8-147. This procedure assumes the power amplifier is functioning properly.
A TILDE ("~") PRECEDING ALL SIGNALS INDICATES NEGATIVE-TRUE LOGIC.
a. Set HEATER jumper to OFF. Is A3TP11 voltage between 0.2V and 0.6V? If yes, go to step b. if no, go
to Power Amplifier Troubleshooting.
b. Is A3TP15 voltage between +0.2 and +0.6 Vdc? If yes, go to step c. If no, A3R18, R19 or U14 is
faulty.
c. Check A3R16 (SET TEMP potentiometer) using the voltage-drop method to ensure that the pot isn't
open or shorted [(measure between R18 -R16 node and U14 (Pin 3)1. Short A3TP15 to A3TP11.
Measure A3U14 (Pin 6). Does the voltage stabilize between -1.5 V and +1.5 Vdc? If yes, go to step
d. If no, A3R21, R23 or U14 is faulty. Remove short.
d. Short A3TP15 to ground (A3TP18). Is A3U14 (Pin 6) more negative than -12V? If yes, go to step e. If
no, A3U14 is faulty. Do not remove short at this time.
e. Is voltage at A3U15 (Pin3) approximately half that of A3U14 (Pin 6) voltage? If yes, go to step f. If
no, A3R25, R26, U1 2 or U15 is faulty.
f. Is voltage at A3U15 (Pin 2) between +1.2 Vdc and +1.3 Vdc? If yes, go to step g. If no, A3R28, R29,
R30 or U15 is faulty.
g. Is A3U1 5 (Pin 7) > +3 vdc? If yes, go to step h. If no, A3R5E, R48D, U8A, or U1 5 is bad.
h. Remove A3TP15 short and short A3TP11 to ground. Is A3U14 (Pin 6) voltage > +12 Vdc? If yes, go
to step i. If not, A3U14 is bad. Remove short.
i. Is A3U15 (Pin 7) between +0.10 and +0.20? If yes, the warmup error amplifier is OK. If no, A3R5E,
R48D, U8A orU15 is faulty.
j. If ending troubleshooting procedures at this point, disconnect power from HP 5517B Laser Head, set all
test jumpers to their left-most (normal) positions, and replace laser head front panel and side covers.
8-148. Power Supply Troubleshooting
NOTE
A TILDE ("~") PRECEDING ALL SIGNALS INDICATES NEGATIVE-TRUE LOGIC.
8-149. If the correct voltage is not observed at A3TP8, TP9, or 1P10, typical power supply troubleshooting should
be followed. +1 5V, -1 5V, and +5V test points must meet the limits listed in
Table 8-5. Voltage Test points and Limits
A3 Test Points
TP8
TP9 (labeled " + 5")
TP10 (labeled "-15")
The following are suggested points to check:
a. External system power source.
Voltage Limits
+ 14V ± 0 3 Vdc +5V ±
0 25 Vdc -15V ± 0.3
Vdc
NOTE
Table 8-5.