Agilent Technologies 81689A Guia do Utilizador descarregar pdf (Página 105)

Chapter 5 Service

Troubleshooting Hints

105

Bias Supplies Problems

Check that the input to the voltage regulators of the bias supplies is at least

1 V greater than their output.

Circuit failures can cause heavy loads of the bias supplies which may pull down the

regulator output voltages.

Check the voltages of bias supplies as tabulated below.

Table 5-1. Bias Supplies Voltages

Table 5-2. Bias Supplies Voltages (MY53xx6xxx)

Some circuits produce their own local bias supplies from the main bias supplies. Be

sure to check that these local bias supplies are active. In particular, the ADC (analog-

to-digital converter), ac input, and front panel sections have local bias supplies.

Always check that the power supplies are free of ac oscillations using an oscilloscope.

Failure of bias supplies will cause many self-test failures.

Bias Supply Minimum Maximum Check At

+5 V Floating +4.75 V +5.25 V U10 pin 2

-5.1 V Floating -4.75 V -5.25 V Anode of CR6

+15 V Floating +14.25 V +15.75 V Anode of CR9

-15 V Floating -14.25 V -15.75 V Cathode of CR10

Bias Supply Minimum Maximum Check At

+3.3 V Floating +3.135 V +3.465 V U203 pin 3

+15 V Floating +14.25 V +15.75 V Anode of CR202

-15 V Floating -14.25 V -15.75 V Cathode of CR203

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Agilent Technologies 81689A Guia do Utilizador Página 105