Keysight / Agilent / HP 34970-66502 Front Panel Display Board

The Keysight/Agilent/HP 34970-66502 is a front panel display board assembly (A2 circuit assembly) that restores the visual interface and operator control of the 34970A and 34972A Data Acquisition/Switch Units. This replacement component houses the vacuum fluorescent display control, high-voltage drivers, and keyboard scanning circuits essential to full instrument operation. The display board communicates with main logic circuits via a two-wire bi-directional serial interface, managing real-time measurement readout, alarm limits, and system status.

## Technical Specifications

• **Display Technology:** Vacuum fluorescent with segment control via +18 V (on) and −18 V (off), cathode bias at −11 V
• **Logic Voltage Levels:** −13 V (logic 1), −18 V (logic 0); −13 V regulated from −18 V supply
• **Interface:** Two-wire bi-directional serial communication to main logic circuits
• **Keyboard Scanning:** Integrated scanning circuits for user input handling
• **Compatibility:** Designed for Keysight 34970A and 34972A units exclusively

## Key Features

• Displays setup parameters, measured values, and alarm thresholds
• Keyboard interface for manual instrument configuration and control
• Vacuum fluorescent display with dedicated high-voltage driver circuitry
• Direct integration with 6½ digit (22-bit) DMM architecture
• Serial protocol for bi-directional data exchange with system controller

## Typical Applications

• Replacement of failed or damaged front panel assemblies in field-deployed 34970A/34972A systems
• Restoration of display and control functionality in data acquisition installations
• Service repair of units with non-functional vacuum fluorescent displays

## Compatibility & Integration

The 34970-66502 integrates with 34970A units equipped with GPIB and RS-232 interfaces, and 34972A units featuring LAN, USB, graphical web interface, and USB memory port connectivity. The parent instruments support scanning rates to 250 channels/second across temperature, DC/AC voltage/current, resistance, frequency, and period measurements. System power requirements are 100/120/220/240 Vac ±10%; 45–66 Hz operation.