Fluke 5720A service manual 1. Analog Motherboard Connectors, Connected to Assembly

Theory of Operation 2

System Interconnect Detailed Circuit Description

Table 2-1. Analog Motherboard Connectors

Motherboard Connector

J101

J111

J201 and J202

J211 and J212

J301 and J302

J311 and J312

J401 and J402

J501 and J502

J511 and J512

J601 and J602

J611 and J612

J701 and J702

J801 and J802

J901 and J902

Connected to Assembly

Wideband Oscillator Assembly (A6)

Wideband Output Assembly (A5)

Switch Matrix Assembly (A8)

Current/Hi-Res Assembly (A7)

Ohms Main Assembly (A10)

Ohms Cal Assembly (A9)

DAC Assembly (A11)

Oscillator Control Assembly (A12) Oscillator Output Assembly (A13)

High Voltage/High Current Assembly (A15)

High Voltage Control Assembly (A14)

Power Amplifier Assembly (A16)

Regulator/Guard Crossing Assembly (A17)

Filter/PA Supply Assembly (A18)

Line INT OUT HI is the calibrator output for ac voltage operation in the 22V range and below, dc voltage operation in the 220V range and below, all resistance functions, and all ac/dc current ranges. Relays on the Current assembly route the current output to the AUX CURRENT OUTPUT binding post via the I OUT line if so selected by the operator. INT SENSE HI is the sense high path during these modes of operation. INT OUT HI is connected to the OUTPUT HI binding post through relay K1. INT SENSE HI is connected to the SENSE HI or OUTPUT HI binding post through relays K2 and K3.

Line HV OUT is the calibrator output for dc voltage operation in the 1100V range, and ac voltage operation in the 220V and 1100V ranges. Line HV SENSE is the sense high path during these modes of operation. HV OUT is connected to the OUT HI binding post through relays K9 and K1. HV SENSE is connected to the SENSE HI or OUTPUT HI binding post through relays K10, K2, and K3.

The 5725A Amplifier output is B OUT HI and the sense high path is B SNS HI. When the 5725A is active, B OUT HI is connected to the OUT HI binding post through relays K4 and K1. When the 5725A Amplifier is inactive, B OUT HI is connected to GUARD CHASSIS by relay K12. Line B SNS HI is tied to B OUT HI through diode clamps CR1 and CR2 and is connected to the SENSE HI or OUTPUT HI binding post through relays K5, K2, and K3.

The cable from the motherboard to the binding posts consists of six insulated wires and six shields, each with its own drain wire. The OUT HI line, SENSE HI line, OUT/SENSE HI line and AUX CURRENT line each connect to an insulated wire and each has a shield around the wire. These shields are connected to OUT LO, SENSE LO, OUT/SENSE LO, and I/V GUARD, respectively. The I/V GUARD line is connected to I GUARD during operation in the current mode or V GUARD during operation in the voltage mode. This selection is done by relay K11.

When the Calibrator is in standby, all binding posts are open-circuited except the GROUND binding post. In addition, GUARD CHASSIS is connected to S COM by K6. When in the operate condition, this connection is broken (K6 energized) and GUARD CHASSIS is connected to V GUARD via K7, which goes to the GUARD binding post, and to OUT LO via K8. GUARD CHASSIS is also connected to OSC LO GD by K13 except during ac or dc millivolt operation, when instead OSC LO GD is connected to S COM.

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