Fluke 5720A service manual Analog Section Detailed Circuit Description

Models: 5720A

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2-56. Analog Section Detailed Circuit Description

Theory of Operation 2

Analog Section Detailed Circuit Description

2-56. Analog Section Detailed Circuit Description

Detailed descriptions of each assembly in the analog section are provided here.

Simplified schematics are provided to supplement the text.

2-57. Filter/PA Supply (A18), Low-voltage Filter/Regulator Section

The Filter assembly receives various ac inputs from the main power transformer and provides unregulated dc to the Regulator/Guard Crossing assembly (A17), and regulated dc supplies +5FR1, -18FR1, and -5FR2 to the DAC assembly. The unregulated supplies are listed in Table 2-8 and the regulated supplies are listed in Table 2-9.

Table 2-8. Unregulated Supplies from the Filter Assembly

Signal Name

+15 OSCR -15 OSCR OSC COM

+5 LHR -5 LHR LH COM

+44 SR

-44 SR

44 S COM*

+17 SR

-17 SR

17 S COM*

+5 FR1R -18 FR1R

FR1 COM

+30 FR1R

FR1R COM

Nominal

Output

27V

27V RETURN

12V

12V RETURN

60V

60V

27V

27V RETURN

12V

27V RETURN

50V RETURN

Tolerance

+/-8V +/-8V

+/-4V +/-4V

+/-15V +/-15V

+/-8V +/-8V

+/-4V +/-8V

+/-15V

Max. P-P

Ripple

2V

2V

3V

2V

3V

3V

3V

3V

2V

2V

3V

Rated Output

200mA

200mA

3.5A

400 mA

155mA

460mA

1.3A

1.3A

400mA

50mA

85 mA

Test

Point

TP2

TP5

TP4

TP1

TP6

TP3

TP7

TP9

TP22

TP10

TP14

TP12

TP17

TP20

TP19

TP15

TP16

+30 FR2R

RETURN

+/-15V

3V

85 mA

TP8

FR2 COM

 

 

 

 

TP11

* 44 S COM and 17 S COM are tied together on the Regulator/Guard Crossing assembly (A17).

Table 2-9. Regulated Supplies from the Filter/PA Supply

Signal Name

-5 FR2

FR2 COM

+5 FR1

-18 FR1

FR1 COM

Nominal

Output

-5V

RETURN

+5V -18V

RETURN

Tolerance

+/-0.3V

+/-0.3V +/-0.9V

Current Limit

0.15A

2A

2A

Rated Output

0.03A

0.1A

0.05A

Test Point

TP13

TP11

TP18

TP21

TP19

2-33

Page 95
Image 95
Fluke 5720A Analog Section Detailed Circuit Description, Filter/PA Supply A18, Low-voltage Filter/Regulator Section