Agilent Technologies 5517B Operation And Service Manual page 91

8-133. Service information for the A3 Assembly is divided into the following procedures:
a. Digital
b. Photodiode and Amplifier
c. Liquid Crystal
d. Subtracting Sample and Hold
e. Power Amplifier
f. Warm-up Error Amplifier
g. Power Supplies
h. Reference Receiver
Consult paragraph 8-67, HP 5517B/C/D Trouble isolation, to determine which procedure to use.
8-134. Standard Troubleshooting Procedures
8-135. In the following tests, reference is frequently made to "localize the defective element by standard
troubleshooting procedures". This consists of the following:
a. The test procedure places a group of IC's in a definite state and:
1. provides the correct values of the input and output signals characteristics,
OR
2. implies use of the schematic to determine the signal characteristics,
OR
3. simply states a suspected component.
b. When the tesUprocedure specifies a suspected component, replace it and run the test again.
c. When signal characteristics are known, measure the signals until a component is found that has
correct inputs but erroneous outputs. Most likely this component is defective. If not, check for:
1. output loading such as a board short
2. shorted input on a downstream circuit
If inputs are incorrect, check for open traces and faulty outputs from previous stages.
d. if an erroneous signal comes from another board, perform the test procedure for the suspected board.
8-136. Digital Troubleshooting
8-137. This procedure covers the clock, dividers, power-on-reset, and state machine blocks of the A3 assembly. This
procedure assumes that the power supplies are functioning properly. The procedure requires use of standard
troubleshooting procedures which are outlined in paragraph 8-135.
8-138. Troubleshooting Strategy. Signature analysis is used in this section to isolate faulty digital components.
Malfunctions in the clock, dividers, or power-on-reset blocks will not allow the signature analyzer to operate
properly. Proper clock operation is verified first, then an attempt at verifying the state machine using signature
analysis is made. If the signature analyzer doesn't work, the dividers and resets must be repaired and then the state
machine can be verified.
When taking signatures, ensure that the heater test jumper is in the off position. Damage to the high voltage power
supply or laser tube assembly could result if these instructions are not adhered to.
IMPORTANT NOTE
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