Test equipment DC power supplies

Agilent 6611C: troubleshooting and error codes

The ServiceForge knowledge base holds 22 documented symptoms for the Agilent 6611C, with 44 ranked causes, 35 diagnostic checks with test points and expected values, and 22 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Power-on self-test fails with ERR annunciator

Display shows ERR annunciator when unit powers on; self-test sequence detects error(s) in digital/DAC circuits

Ranked causes

1. Checksum error in Read-only Non-volatile ROM (unknown)
2. Checksum error in Config Non-volatile ROM (unknown)
3. Checksum error in Cal Non-volatile ROM (unknown)
4. Checksum error in State Non-volatile ROM (unknown)
5. Checksum error in RST Non-volatile ROM (unknown)
6. RAM test failed (unknown)
7. 12-bit DAC test failed at 0V output (unknown)
8. 12-bit DAC test failed at mid-range (unknown)
9. 12-bit DAC test failed at mid-range alternate (unknown)
10. 12-bit DAC test failed at full scale (unknown)
11. 8-bit DAC test failed (unknown)
12. Digital I/O test failed (unknown)
13. RS-232 input buffer overrun (unknown)
14. RS-232 framing error (unknown)
15. RS-232 parity error (unknown)
16. RS-232 UART input overrun (unknown)
17. Front Panel comm UART input overrun (unknown)
18. Front Panel comm UART framing error (unknown)
19. Front Panel comm UART parity error (unknown)
20. Front Panel firmware input buffer overrun (unknown)

20 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Calibration: Initialize power supply after Interface board replacement

EEPROM on A2 Interface board stores GPIB address, model number, and calibration constants. After Interface board replacement, supply must be reinitialized and calibrated.

Ranked causes

1. Interface board replaced or requires reinitialization (common)
2. ROM upgrade performed on Interface board (occasional)

First check

Enable Calibration mode

Test point: Control panel
Expected: Calibration mode active

3 more checks with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Constant current noise (PARD) exceeds specification

Output ripple and noise in constant current mode exceeds RMS current limit at 20 Hz to 20 MHz

Ranked causes

1. Electronic load contributing excess ripple or improper measurement setup (common)
2. External equipment interference or improper measurement setup (common)

First check

Verify test setup and baseline noise with supply off

Test point: RMS voltmeter across current monitoring resistor
Expected: Minimal noise reading with supply off
Tools: RMS voltmeter, current monitoring resistor

1 more check with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

OUT OF RANGE message appears or error code 402 during calibration password entry

Display shows OUT OF RANGE or GPIB returns error code 402 when entering calibration password

Ranked causes

1. Incorrect calibration password entered (common)
2. Password forgotten and not recoverable (occasional)

First check

Verify correct calibration password entered

Test point: Front panel or GPIB input
Expected: Password accepted; calibration mode enabled

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Built-in self-test failure high voltage

Power supply fails self-test at startup; cannot proceed to calibration or verification

Ranked causes

1. Digital circuit failure detected by self-test (unknown)

First check

Run built-in self-test at power-on

Test point: Power supply startup
Expected: All tests pass

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

CAL DENIED message appears during calibration

Display shows CAL DENIED or GPIB returns error code 401 when attempting calibration

Ranked causes

1. INHIBIT CAL switch S201 set to inhibit calibration (common)

First check

Inspect S201 switch position on A2 Interface board

Test point: S201 switches 3 and 4
Expected: Both switches in Off position for normal calibration

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Calibration: ROM upgrade without affecting existing calibration

After upgrading Interface board ROM, supply can be reinitialized while preserving calibration data.

Ranked causes

1. ROM upgrade completed on Interface board (rare)

First check

Enable Calibration mode and press 0 and 1 simultaneously

Test point: Display
Expected: EEINIT <model> displayed

3 more checks with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Constant current load effect out of specification

Output current changes excessively when load changes from full-scale voltage to short circuit

Ranked causes

1. Load regulation performance degraded or CC annunciator not activating (occasional)

First check

Measure current at full-scale voltage in CC mode

Test point: DVM reading across current monitoring resistor
Expected: Recorded current value used as baseline
Tools: DVM

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Constant current programming and readback inaccurate

Current output does not match programmed value or display reading incorrect when set to zero or full scale

Ranked causes

1. Incorrect connection or setup of current monitoring resistor (common)

First check

Measure voltage drop across current monitoring resistor at zero amps

Test point: Across current monitoring resistor
Expected: Within specified limits for programming and readback at 0 Amps
Tools: DVM

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Constant current source effect out of specification high voltage

Output current changes excessively when AC line voltage varies from minimum to maximum

Ranked causes

1. Line voltage regulation performance degraded or supply not stable across line range (occasional)

First check

Measure current at minimum rated line voltage

Test point: DVM reading across current monitoring resistor
Expected: Recorded current value used as baseline
Tools: DVM

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Constant current transient response exceeds 100 microseconds

Output voltage takes longer than 100 microseconds to return to within spec during load transients

Ranked causes

1. Output filter or feedback circuit degradation affecting transient response (occasional)

First check

Set up transient test and measure settling time

Test point: Oscilloscope across +S and -S sense terminals
Expected: Voltage returns to within specification in less than 100 microseconds for both loading and unloading transients, <100 microseconds
Tools: Oscilloscope, electronic load with transient generator

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Current sink operation incorrect

Supply fails to operate in current sink mode or readback value incorrect when sourcing external power

Ranked causes

1. Incorrect current sink mode configuration or external power supply setup (common)

First check

Verify current sink mode readback accuracy

Test point: Across current monitoring resistor
Expected: Difference between DVM-calculated current and display reading within specified limits
Tools: DVM

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

CV load effect exceeds specification

Change in output voltage from full load to no load exceeds specified limit

Ranked causes

1. CV regulation circuit malfunction (unknown)

First check

Measure output voltage at full-scale load current

Test point: +S and -S terminals
Expected: CV annunciator on, current at full-scale value in Table 2-2

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

CV noise (PARD) exceeds specification

Peak-to-peak or RMS ripple and noise on output voltage exceeds specified limit in frequency range

Ranked causes

1. Output filter or noise suppression circuit malfunction (unknown)

First check

Measure output noise peak-to-peak on oscilloscope

Test point: (+) and (-) output terminals
Expected: Peak-to-peak waveform not exceeding limits in performance test record card under CV Noise (PARD)

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

CV source effect exceeds specification high voltage

Change in output voltage from minimum to maximum AC line voltage exceeds specified limit

Ranked causes

1. AC line voltage regulation circuit malfunction (unknown)

First check

Set AC input to minimum rated line voltage

Test point: Variable voltage transformer
Expected: Minimum rated line voltage (e.g., 104 Vac for 115 Vac nominal)

3 more checks with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low range current readback inaccurate at +20mA

20 milliampere current range measurement incorrect when programmed at positive 20 mA

Ranked causes

1. Meter overrange or incorrect voltage setting (common)

First check

Measure current at 8V positive side low range

Test point: Through DMM in current mode
Expected: Within specified limits for 20mA Range Current Readback Accuracy @ +20mA
Tools: DMM

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low range current readback inaccurate at −20mA

20 milliampere current range measurement incorrect when sinking 20 mA from external power source

Ranked causes

1. Incorrect external power supply configuration or connections (common)

First check

Measure current at −20mA negative sink

Test point: Through DMM in current mode
Expected: Within specified limits for 20mA Range Current Readback Accuracy @ −20 mA
Tools: DMM

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low range current readback inaccurate at 0A

20 milliampere current range display or measurement does not match actual output at zero volts

Ranked causes

1. Low range readback not selected or incorrect DMM connection (common)

First check

Measure current at zero volts low range

Test point: Through DMM in current mode
Expected: Within specified limits for 20mA Range Current Readback Accuracy @ 0A
Tools: DMM

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

No output voltage or current with CV/CC annunciators off

Unit produces neither CV nor CC indication; UNR annunciator shown indicating neither voltage nor current control active

Ranked causes

1. Main power transformer failure or output stage problem (unknown)

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Transient recovery time exceeds specification

Output voltage does not recover to specified value within required time after 50% load current change

Ranked causes

1. CV loop response or compensation circuit malfunction (unknown)

Unit malfunction suspected high voltage

Technician needs to verify problem is in the dc power supply itself before troubleshooting

Ranked causes

1. Problem is external or associated circuit, not the power supply (unknown)

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Voltage programming and readback inaccuracy

Output voltage readings on DVM and front panel display do not match specifications at 0V or full-scale voltage

Ranked causes

1. Voltage programming or readback circuit malfunction (unknown)

First check

Verify DVM reading at 0V programming matches front panel display

Test point: +S and -S terminals
Expected: Within limits specified in performance test record card for model under Voltage Programming and Readback @ 0 Volts

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Error codes

Code	Meaning	Trigger	Severity
`401`	Calibration inhibited by INHIBIT CAL switch S201	Attempt to calibrate over GPIB when inhibit switch is set	warning
`402`	Incorrect calibration password entered	Invalid password supplied during GPIB calibration mode entry	warning
`E1`	Checksum in Read-only Non-volatile ROM	Power-on self-test detects checksum mismatch	error
`E10`	RAM test failed	Power-on self-test detects RAM failure	error
`E11`	12-bit DAC test failed at 0V output	0 written to DAC U241A and B; ADC U242 not at 133 ±7 counts	error
`E12`	12-bit DAC test failed at mid-range	4095 written to U241A, 0 to U241B; ADC U242 not at 71 ±7 counts	error
`E13`	12-bit DAC test failed at mid-range alternate	0 written to U241A, 4095 to U241B; ADC U242 not at 71 ±7 counts	error
`E14`	12-bit DAC test failed at full scale	4095 written to DAC U241A and U241B; ADC U242 not at 10 ±7 counts	error
`E15`	8-bit DAC test failed	10 and 240 written to DAC U244; ADC U242 not at 10 and 240 ±7 counts	error
`E2`	Checksum in Config Non-volatile ROM	Power-on self-test detects checksum mismatch	error
`E213`	RS-232 input buffer overrun	RS-232 receiver input buffer overflows	warning
`E216`	RS-232 framing error	RS-232 receiver detects framing error on incoming data	warning
`E217`	RS-232 parity error	RS-232 receiver detects parity bit mismatch	warning
`E218`	RS-232 UART input overrun	UART receiver cannot process incoming data fast enough	warning
`E220`	Front Panel comm UART input overrun	Front panel UART receiver buffer overflows	error
`E221`	Front Panel comm UART framing error	Front Panel UART detects framing error	error
`E222`	Front Panel comm UART parity error	Front Panel UART detects parity bit mismatch	error
`E223`	Front Panel firmware input buffer overrun	Front Panel firmware receiver buffer overflows	error
`E3`	Checksum in Cal Non-volatile ROM	Power-on self-test detects checksum mismatch	error
`E4`	Checksum in State Non-volatile ROM	Power-on self-test detects checksum mismatch	error
`E5`	Checksum in RST Non-volatile ROM	Power-on self-test detects checksum mismatch	error
`E80`	Digital I/O test failed	SEC_PCLR written low and high; readback through Xilinx fails	error

Likely causes and actions for each code are in ServiceForge. Connect ServiceForge to your AI

Community

0 fixes logged by technicians through their AI, with outcomes, for this model.

ServiceForge knowledge base record. Field-unverified unless technicians confirmed it. A teaching summary of the record, not a service manual. Export 2026-10-14.