Test equipment and power supplies · Agilent Mobile Communications family

Agilent 66311B: troubleshooting and error codes

The ServiceForge knowledge base holds 25 documented symptoms for the Agilent 66311B, with 45 ranked causes, 57 diagnostic checks with test points and expected values, and 23 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 failure

ERR annunciator comes on during power-up self-test sequence; digital and DAC circuits tested

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 0 input (unknown)
8. 12 bit DAC test failed at 4095/0 input (unknown)
9. 12 bit DAC test failed at 0/4095 input (unknown)
10. 12 bit DAC test failed at 4095 input (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 dc source after A2 Interface board replacement

Procedure to reinitialize and calibrate supply when Interface board has been replaced

Ranked causes

1. A2 Interface board has been replaced (rare)
2. Calibration procedure required after initialization (common)

First check

Enable Calibration mode

Test point: Front panel keys
Expected: Press Shift, then Cal, then Enter

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

CAL DENIED appears on display during calibration

Display shows 'CAL DENIED' message when attempting to calibrate the unit

Ranked causes

1. Inhibit Calibration switch (S201) is set to ON (common)

First check

Verify switch S201 position

Test point: S201 on A2 Interface board near GPIB connector
Expected: Switch 3 OFF, Switch 4 OFF for Normal mode

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

Calibration denied or error 401 on GPIB calibration

CAL DENIED message appears on display when calibration is attempted, or error code 401 occurs when calibrating over GPIB due to INHIBIT CAL switch being set

Ranked causes

1. INHIBIT CAL switch (S201) set to ON position (common)

First check

Verify S201 switch position

Test point: S201 Switch 3 and Switch 4 on A2 Interface board
Expected: Switch 3 Off, Switch 4 Off for Normal operation

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

Calibration: Annual or component replacement

Calibration required annually and after replacing A1 power module or A2 interface board. If A2 replaced, must initialize first then calibrate using correct password.

Ranked causes

1. A1 or A2 component replaced (rare)

First check

Verify component replacement

Test point: Physical inspection
Expected: A1 or A2 module replaced

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

Calibration: CC noise verification

Measure RMS current noise in constant current (CC) mode at full scale output to verify it does not exceed specification limits

Ranked causes

1. Excessive noise in CC mode output (unknown)

First check

Verify test environment for external noise sources

Test point: Test setup
Expected: No external noise interference detected

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

Calibration: DC source reinitialization

After replacing A2 Interface board containing EEPROM with constants and references affecting alignment, supply must be reinitialized and calibrated

Ranked causes

1. A2 Interface board replaced (occasional)

First check

Enable Calibration mode

Test point: Front panel controls
Expected: Calibration mode active

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

Calibration: Disable protection features caution

Disable overcurrent/thermal protection for troubleshooting. Default is protection enabled (NO-PROTECT OFF). Must be reset after power cycle. Overvoltage protection cannot be disabled.

Ranked causes

1. Protection feature needs to be disabled for troubleshooting (rare)

First check

Access protection feature menu

Test point: Display
Expected: NO-PROTECT<OFF> shown

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

Calibration: Incorrect password

Wrong calibration password prevents calibration mode entry. Displays 'OUT OF RANGE' on front panel or error 402 on GPIB interface.

Ranked causes

1. Incorrect calibration password entered (occasional)

First check

Enter calibration password

Test point: Display or GPIB
Expected: Calibration mode enabled

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

Calibration: Manual fan speed control

Reduce fan speed for acoustic testing or light load conditions. Default is Automatic; must be reset after power cycle.

Ranked causes

1. Fan speed adjustment needed for test conditions (common)

First check

Select FAN:MODE menu

Test point: Display
Expected: FAN:MODE<AUTO.> shown

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

Constant current sink mode not functioning

Output current does not decrease linearly as voltage increases in negative current mode

Ranked causes

1. Current sink circuit malfunction (unknown)

First check

Verify negative current displayed at 0V output

Test point: Front panel display
Expected: Negative current value, approximately 2.8A

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 mode not activated

CC annunciator not illuminating when load is adjusted to full-scale voltage

Ranked causes

1. Load impedance too high in CV mode (common)

First check

Verify CC annunciator is illuminated

Test point: Front panel CC indicator
Expected: CC annunciator on

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

Error code 401 occurs during GPIB calibration

Error 401 displayed or reported when attempting calibration over GPIB interface

Ranked causes

1. Inhibit Calibration switch (S201) is set to ON (common)

First check

Verify switch S201 position

Test point: S201 on A2 Interface board near GPIB connector
Expected: Switch 3 OFF, Switch 4 OFF for Normal mode

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

Low range current readback inaccurate

20mA range current readings do not match between DMM and front panel display

Ranked causes

1. Low range readback circuit out of specification (unknown)

First check

Measure current at 0A with 20mA range selected

Test point: Between DMM and current monitoring resistor
Expected: Within specification at 0A per test record
Tools: DMM in current mode

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

Output current changes with line voltage variation

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

Ranked causes

1. Source regulation out of specification (unknown)

First check

Measure output current at minimum rated line voltage

Test point: Across current monitoring resistor
Expected: Within specification for CC Source Effect
Tools: DVM, variable voltage transformer

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

Output current changes with load impedance

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

Ranked causes

1. Load regulation out of specification (unknown)

First check

Measure output current at full-scale voltage

Test point: Across current monitoring resistor
Expected: Within specification for CC Load Effect test
Tools: DVM

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

Output current programming and readback inaccurate

Current values programmed and displayed do not match measured values across current monitoring resistor

Ranked causes

1. Out of specification current measurement (unknown)

First check

Measure voltage drop across current monitoring resistor at 20mA programming

Test point: Across current monitoring resistor
Expected: Within specification limits for 0A range
Tools: DVM

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

Output current ripple and noise excessive

RMS noise measured on output exceeds specification in 20Hz to 20MHz band

Ranked causes

1. PARD (Periodic and Random Deviations) out of specification (unknown)

First check

Measure RMS voltage across current monitoring resistor

Test point: Across current monitoring resistor in 20Hz to 20MHz band
Expected: Within PARD specification limit
Tools: RMS voltmeter

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

Output noise and ripple excessive

Peak-to-peak or RMS ac voltage superimposed on dc output exceeds specification limits

Ranked causes

1. EMI coupling, output filter degradation, or switching noise issue (unknown)

First check

Verify oscilloscope configuration

Test point: Oscilloscope bandwidth and probe
Expected: 20 MHz bandwidth limit, RF tip probe on scope probe
Tools: Oscilloscope with RF probe

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

Output voltage changes with load current

Output voltage is not stable when load current changes from full load to no load

Ranked causes

1. Output impedance or regulation circuit drift (unknown)

First check

Verify CV regulation at full load

Test point: +S to -S terminals
Expected: CV annunciator on, front panel display at full-scale voltage
Tools: Digital voltmeter

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

Output voltage varies with ac line voltage

Output voltage is not stable when ac line input voltage changes between minimum and maximum rated values

Ranked causes

1. Source regulation circuit drift or transformer coupling issue (unknown)

First check

Set line voltage to minimum rated value

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

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

ROM upgrade: U205 Interface ROM replacement caution

Procedure to upgrade Primary Interface ROM (U205) on A2 Interface board to update firmware revision

Ranked causes

1. Firmware update required (occasional)

First check

Identify current firmware revision from front panel

Test point: Address key, Up/Down annunciator to ROM: <A.xx.xx>
Expected: ROM: <A.xx.xx> displayed

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

Transient recovery time excessive

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

Ranked causes

1. Control loop response or compensation circuit issue (unknown)

First check

Observe transient response on oscilloscope

Test point: (+) to (-) terminals
Expected: Initial negative dip settles within 35 microseconds, recovery within 20mV band of final voltage
Tools: Oscilloscope

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

Transient response time exceeds specification

Output voltage does not return to specified value within 35 microseconds after current transient

Ranked causes

1. Compensation setting incorrect or circuit performance degraded (common)

First check

Verify compensation mode set to High capacitance

Test point: Front panel compensation setting
Expected: High capacitance mode selected

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

Voltage programming and readback inaccurate

Front panel display and/or GPIB readback voltage values do not match expected values at 0V or full-scale settings

Ranked causes

1. Calibration or display offset error (unknown)

First check

Measure output voltage at 0V setting

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

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 denied	Attempted calibration when INHIBIT CAL switch S201 is set	error
`401`	Calibration denied due to Inhibit Calibration switch setting	Attempted calibration over GPIB when Inhibit Calibration switch (S201) is enabled	warning
`402`	Incorrect calibration password (GPIB interface)	Wrong password entered during GPIB calibration mode access attempt	error
`E1`	Checksum error in Read-only Non-volatile ROM	Power-on self-test detects ROM checksum failure	error
`E10`	RAM test failed	Power-on self-test detects RAM memory failure	error
`E11`	12 bit DAC test failed at 0 input	DAC test: 0 written to U241A/B, ADC U242 does not read 133 +/- 7 counts	error
`E12`	12 bit DAC test failed at 4095/0 input	DAC test: 4095 to U241A, 0 to U241B, ADC U242 does not read 71 +/- 7 counts	error
`E13`	12 bit DAC test failed at 0/4095 input	DAC test: 0 to U241A, 4095 to U241B, ADC U242 does not read 71 +/- 7 counts	error
`E14`	12 bit DAC test failed at 4095 input	DAC test: 4095 written to U241A/B, ADC U242 does not read 10 +/- 7 counts	error
`E15`	8 bit DAC test failed	DAC test: 10 and 240 written to U244, ADC U242 does not read 10 and 240 +/- 7 counts	error
`E2`	Checksum error in Config Non-volatile ROM	Power-on self-test detects ROM checksum failure	error
`E213`	RS-232 input buffer overrun	Serial data received faster than processor can handle	warning
`E216`	RS-232 framing error	Invalid start or stop bit sequence detected on RS-232 input	warning
`E217`	RS-232 parity error	Parity bit does not match received data on RS-232 input	warning
`E218`	RS-232 UART input overrun	UART receive buffer filled before data retrieved	warning
`E220`	Front Panel comm UART input overrun	Front panel communication UART receive buffer filled before data retrieved	error
`E221`	Front Panel comm UART framing error	Invalid frame detected in front panel serial communication	error
`E222`	Front Panel comm UART parity error	Parity error detected in front panel serial communication	error
`E223`	Front Panel firmware input buffer overrun	Front panel firmware receive buffer filled before data processed	error
`E3`	Checksum error in Cal Non-volatile ROM	Power-on self-test detects ROM checksum failure	error
`E4`	Checksum error in State Non-volatile ROM	Power-on self-test detects ROM checksum failure	error
`E5`	Checksum error in RST Non-volatile ROM	Power-on self-test detects ROM checksum failure	error
`E80`	Digital I/O test failed	SEC_PCLR signal cannot be written low and high, or read-back 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.