Agilent Technologies 6680A Post-Repair Calibration When Required, Inhibit Calibration Jumper

Post-Repair Calibration

When Required

Calibration is required annually and also whenever certain components are replaced. If components in any of the circuits listed below are replaced, the supply must be recalibrated.

Note	For calibration procedures, see Appendix A of the Operating Manual.
	Location	Component
A10 Control Board		CV/CC DACs/operational amplifiers, CV/CC control circuit amplifiers, readback
		DAC/operational amplifier, readback comparators.
A1 Front Panel Assy		A1 Front Panel Board or EEPROM AlU6.
		Note: If either of these front panel components is replaced, the power supply must first be
		reinitialized before calibration (see "EEPROM Initialization" ) .

Inhibit Calibration Jumper

If CAL DENIED appears on the display when front panel calibration is attempted (or error code 1 occurs when GPIB calibration is attempted on a Systems Supply), the INHIBIT CAL jumper (see Figure 3-15) is installed. This prevents the power supply calibration from being changed. To calibrate the power supply first move this jumper from the INHIBIT CAL position to the NORM position.

Calibration Password

In order to enter the calibration mode, you must use the correct password as described in Appendix A of the Operating Manual. As shipped from the factory, the supply's model number (e.g., "6681") is the password. If you use an incorrect password, PASSWD ERROR appears on the display during front panel calibration, or error code 2 occurs during GPIB calibration, and the calibration mode is disabled. If you do not know the password, you can recover the calibration function by restoring the preset factory calibration constants as described below.

Restoring Factory Calibration Constants

This procedure allows you to recover the factory calibration constants. The ability to do this allows you to operate the power supply for troubleshooting and/or to recalibrate it as required. To restore the original factory calibration constants, proceed as follows:

1.Turn off the supply and remove the top cover.

2.Move the jumper in test header J3 on the A1 Front Panel Board from the NORM to the FACTORY PRESET CAL position (see Figure 3-15).

3.Turn on the power supply and note that ADDR 5 and then PWR ON INIT appear briefly on the front panel display.

4.When PWR ON INIT no longer appears, the supply's factory calibration constants have been restored and the password has been changed to 0. There is no longer any password protection. You can now turn off the supply and restore the calibration jumper to the NORM position (see Figure 3-15).

5.Turn on the supply. You may now set a new password (if desired) and recalibrate the power supply.

62 Troubleshooting