Agilent Technologies 5071A A1 Motherboard Circuit Description, Overvoltage Protection Circuit

Assembly-Level Service

Theory of Operation

Table 3-6. Power Supply Block Interconnections

Option 048: The following signal name information in table 3-6 on page 3-23 is changed:

•The voltage range in the third row is changed from 22-42 Volts to 40-58 Volts.

•The voltage range in the fourth row is changed from 32-38 Volts to 45-51 Volts.

•The voltage range in the fifth and sixth row is changed from 22-42 Volts to 40-58 Volts.

•The only signal names present in the tenth row are: DC Valid, DC Valid Return, AC Valid, and AC Valid Return.

A1 Motherboard Circuit Description

Overvoltage Protection Circuit

Option 048: The dc voltage ratings specified in the last sentences of paragraphs four and five on page 3-24 are changed:

56 Vdc is 72 Vdc and 50 Vdc is 65 Vdc.

Option 048: The dc voltage rating specified in the last sentence of paragraph three on page 3-25 is changed:

56 Vdc is 72 Vdc.

External Dc Input Circuit

Option 048: The paragraph that describes the external dc input circuit on page 3-25 is changed:

A1J1 receives the dc input from an external dc source (40-58V). The dc voltage is then routed to a filter consisting of A1L1 and A1C2 before being sent to A11 Power Steering Logic Assembly via connector A1J4. Diode A1CR2 prevents any damage to the instrument if the external dc-input source is reversed. The current handling capability of A1CR2 is higher than that of the external input fuse (2.5A) so the fuse blows before the diode fails.

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