What causes A/D link fail on HP 3478A Multimeter?
The A/D Link failure occurs when the Chassis Common Processor (Main Controller, U501) cannot communicate with the Floating Common Processor (A/D Controller, U462).
Why does my HP 3478A show Control ROM Fail?
The Control ROM (U502) is the most likely cause of Control ROM failure.
What causes U501 RAM to fail in HP Multimeter?
The cause of U501 RAM failure is a defective U501.
General| Operating Temperature | 0°C to 55°C |
|---|---|
| Measurement Functions | DC Voltage, AC Voltage, DC Current, AC Current, Resistance |
| DC Current Range | 300 μA, 3 mA, 30 mA, 300 mA, 3 A |
| AC Current Range | 300 μA, 3 mA, 30 mA, 300 mA, 3 A |
| Display | 5.5 digit LED display |
The instrument chassis and cabinet must be connected to an electric ground.
Do not operate the instrument in the presence of flammable gases or fumes.
Operating personnel must not remove instrument covers.
Do not attempt internal service or adjustment unless qualified personnel are present.
Do not substitute parts or modify the instrument due to the danger of introducing hazards.
Warnings precede potentially dangerous procedures throughout this manual.
The specifications of the 3478A are the performance characteristics of the multimeter.
Instrument identification is based on the serial number located on the multimeter's rear panel.
The following options are available for the 3478A.
The following is a list of available accessories for the 3478A.
This section of the manual has the necessary information and instructions to install and interface the HP-IB Model 3478A Digital Multimeter.
The 3478A was carefully inspected both mechanically and electrically before shipment.
The 3478A requires a power source of 100V, 120V, 220V, or 240V ac with ±10% tolerance.
To protect operating personnel, the National Electrical Manufacturing Association (NEMA) recommendation is to ground the instrument panel and cabinet.
The 3478A is compatible with the Hewlett-Packard Interface Bus (HP-IB).
To prevent electrical fire or shock hazards, do not expose the instrument to rain or excessive moisture.
This section has information and instructions for the operation of the 3478A Multimeter.
Figure 3-1 shows the front and rear panel features of the 3478A, with labels identifying each control.
The 3478A has one set of Input Terminals on the front panel and one set on the rear panel.
DC Volts Measurements are performed by measuring DC volts, AC volts, and resistance.
The 3478A is able to make resistance measurements from 0001 ohm to 30 megohm.
When the AC Volts function is selected, the display shows 'MVAC' or 'VAC'.
The 3478A has three local trigger modes: Single, Manual, and External.
The 3478A is time division multiplexed, and the display shows the selected function and range.
This section of the manual contains all performance tests and calibration procedures.
Table 4-2 lists the recommended test equipment for the Performance Tests.
If the 3478A fails any of the Performance Tests, first attempt the Calibration Procedure.
The DC Volts Test Card lists the DC Volts test steps and their required limits.
The AC Volts Test Card summarizes the instrument specifications for AC Volts.
The Ohms Performance Test Card is only valid if the Ohms function was last calibrated.
This section describes the calibration procedures for the 3478A.
This section has information for ordering replaceable parts.
To obtain a part, address order or inquiry to your Hewlett-Packard Office.
The disassembly procedure applies to 3478A's with serial prefix 2619 and above.
This section contains information used to adapt this manual to instruments with serial numbers lower than those listed.
The following serial numbers are affected by backdating.
Material changes list for the Revision B printed circuit boards are shown in Table 6-1.
This section of the manual has information on how to troubleshoot and repair the 3478A multimeter.
Any interruptions of the protective ground conductor can make the instrument dangerous.
This section provides troubleshooting procedures for various faults.
The 3478A Self-Test is designed to make sure that the instrument's internal logic is operating correctly.
This shows the Chassis Common CPU's (Main Controller) RAM failure.
If the CAL RAM FAIL message is displayed after a Self-Test routine, the most likely cause is Calibration RAM failure.
This Service Group has the DC Volts and DC Current troubleshooting information for the 3478A.
Before troubleshooting the 3478A, make sure the instrument is operating correctly.
This section covers troubleshooting for DC Volts and DC Current functions.
This section covers troubleshooting for overload, floating, constant zero, or noisy readings.
This section covers troubleshooting for the Input Circuitry.
This Service Group has the general and detailed description of the operating circuitry of the HP-IB Model 3478A Multimeter.
This section provides a block diagram of the 3478A's circuitry.
This section explains the input circuitry for the 3478A.
This section explains the AC to DC Converter stages.
This section explains the A/D Converter and Control logic.
This section explains the Chassis Common Circuitry.
General schematic notes are also included to gain an understanding of how to use the schematics.
This is a block diagram of the 3478A.
Component locator table for Input Circuitry and Ohms Current Source.
Schematic diagram for the AC to DC Converter.
Schematic diagram for the power supply.
This appendix contains a general description of the Hewlett-Packard Interface Bus (HP-IB).
The Hewlett-Packard Interface Bus (HP-IB) is a parallel bus of 16 active signal lines.
This section defines key terms related to the HP-IB system.
Types of information passed over the HP-IB are comprised of twelve messages.
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