Test equipment and power supplies · E36xx series family

Agilent E3631A: troubleshooting and error codes

The ServiceForge knowledge base holds 18 documented symptoms for the Agilent E3631A, with 31 ranked causes, 67 diagnostic checks with test points and expected values, and 47 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Unit does not power on

Power supply is completely inoperative, no display or output.

Ranked causes

1. AC power cord not connected (common)
2. Front-panel power switch not pressed (common)
3. Power-line fuse missing or incorrect (common)
4. Incorrect power-line voltage setting (occasional)

First check

AC power cord connection

Test point: Power supply inlet
Expected: Power cord firmly connected

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

Unit is inoperative or does not power on

Power supply does not turn on; no output or indicator lights

Ranked causes

1. AC power cord not connected (common)
2. Front-panel power switch not depressed (common)
3. Power-line fuse blown or missing (common)
4. Wrong power-line voltage setting (occasional)

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

Bias supply voltage out of specification

Measured bias supply voltage outside specified limits

Ranked causes

1. Regulator input voltage insufficient (common)
2. Circuit failure or excessive load on supply (occasional)
3. AC oscillation on power supply output (rare)

First check

Measure +5V Floating supply voltage

Test point: U1 pin 2 on top board
Expected: 4.75 V to 5.25 V, +/- 0.25 V
Tools: DMM

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

Unit fails built-in self-test

Self-test does not complete or reports failures

Ranked causes

1. Wrong power-line voltage setting (common)
2. Terminal connections present during test (common)
3. DAC U12 integrated circuit failure (occasional)

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

Calibration: Output voltage and current caution

Procedure to calibrate +6V, +25V, and -25V outputs. Unsecure power supply, disconnect loads, enter calibration mode by pressing Calibrate key at power-on for 5 seconds until beep.

Ranked causes

1. Output voltage requires recalibration (common)
2. Output current requires recalibration (common)

First check

Unsecure the power supply

7 more checks with pass and fail actions, 8 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Power supply fails self-test

Unit powers on but does not pass internal self-test; may display error or not initialize properly.

Ranked causes

1. Incorrect power-line voltage selected (common)
2. Load connected during self-test (common)

First check

Power-line voltage setting correct

Test point: Voltage selector
Expected: Matches local AC mains voltage

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

Unit displays errors 740 through 748

Error codes 740-748 displayed on unit

Ranked causes

1. Power loss during calibration or state change (common)
2. Hardware failure (rare)

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

Calibration program configuration

Software setup parameters for GPIB addresses and current shunt value used in calibration.

Ranked causes

1. Current shunt value mismatch or incorrect GPIB addresses (common)

First check

Verify current shunt value matches hardware

Test point: Current_shunt variable
Expected: 0.01 ohm or actual shunt value in use

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

Calibration: CC Line Regulation caution

Measure change in output current from minimum to maximum AC line voltage (±10% nominal) in constant current mode

Ranked causes

1. CC line regulation out of specification (unknown)

First check

Measure current at low line voltage (-10% nominal)

Test point: Across 0.1Ω current monitoring resistor
Expected: Record baseline current at low line voltage
Tools: Digital voltmeter, variable voltage transformer, electronic load, 0.1Ω resistor

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

Calibration: CC Load Regulation

Measure change in output current from full-scale voltage to short circuit in constant current mode

Ranked causes

1. CC load regulation out of specification (unknown)

First check

Measure current at full-scale output voltage (constant voltage mode)

Test point: Across 0.1Ω current monitoring resistor
Expected: Record baseline current with load in constant voltage mode
Tools: Digital voltmeter, electronic load, 0.1Ω resistor

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

Calibration: Current Programming and Readback Accuracy

Verify that current programming over remote interface and front panel readback match specifications for 0A and full-scale current on +6V, +25V, and -25V outputs

Ranked causes

1. Current programming or readback out of specification (unknown)

First check

Measure 0A output current at programming

Test point: Across 0.1Ω current monitoring resistor
Expected: +6V: 0A ±10mA; +25V: 0A ±4mA; -25V: 0A ±4mA, +/-10mA to ±4mA depending on output
Tools: Digital voltmeter, 0.1Ω resistor

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

Calibration: E3631A voltage and current adjustment

Software calibration procedure using GPIB interface with Agilent 34401A DMM and 0.01 ohm current shunt to adjust output voltage and current accuracy for three power supply outputs.

Ranked causes

1. Voltage and current calibration required (unknown)

First check

Disable calibration security

Test point: CAL:SEC:STAT
Expected: OFF

9 more checks with pass and fail actions, 5 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Calibration: Normal Mode Current Noise (CC Ripple and Noise)

Measure RMS output current noise in frequency range 20Hz to 20MHz during constant current operation

Ranked causes

1. CC ripple and noise exceeds specification (unknown)

First check

Measure RMS current noise across resistive load

Test point: Across load resistor (1.2Ω for +6V, 25Ω for ±25V)
Expected: +6V: ≤2mA; +25V: ≤0.5mA; -25V: ≤0.5mA, ≤2mA for +6V, ≤0.5mA for ±25V
Tools: RMS voltmeter, resistive load (1.2Ω or 25Ω)

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

Calibration: Performance verification

Verify power supply meets specifications after repairs to specific circuits

Ranked causes

1. Need to verify output specifications after circuit repair (common)

First check

Perform power-on self-test

Test point: Front panel display
Expected: PASS displayed (or FAIL with ERROR annunciator if issue)

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

Calibration: Rated voltage outputs high voltage

Check that power supply develops rated voltage outputs on all supplies (+6V, +25V, -25V) with no load and responds to front panel control

Ranked causes

1. Outputs not at rated voltage or unresponsive to control (unknown)

First check

Power supply powers on and enters reset state

Test point: Front panel indicators
Expected: OFF annunciator on, +6V annunciator on

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

Calibration: Self-test verification

Verify power supply is operational using self-test function

Ranked causes

1. Initial verification of power supply operation required (common)

First check

Observe automatic self-test result on power-up

Test point: Front panel display and ERROR annunciator
Expected: PASS displayed (indicates power supply operational)

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

Calibration: Unsecure power supply with security code

Front panel procedure to enter security code and unsecure the E3631A for calibration operations

Ranked causes

1. Power supply secured with calibration security code (common)

First check

Turn on calibration mode

Test point: Front panel Calibrate key
Expected: Beep heard after ~5 seconds, CAL MODE message displayed
Tools: None

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

Calibration: Unsecure power supply without security code caution

Internal jumper bypass procedure when security code is forgotten; requires opening instrument cover and shorting JP1

Ranked causes

1. Security code forgotten or unknown (occasional)

First check

Disconnect power and load connections

Test point: Power cord and front terminals
Expected: All connections removed
Tools: None

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

Error codes

Code	Meaning	Trigger	Severity
`-330`	Self-test failed	Self-test execution	critical
`-350`	Too many errors	Multiple errors detected during operation	critical
`501`	Isolator UART framing error	Communication between isolator and main processor	error
`502`	Isolator UART overrun error	Isolator UART buffer overflow during data transfer	error
`511`	RS-232 framing error	RS-232 serial communication	error
`512`	RS-232 overrun error	RS-232 buffer overflow during reception	error
`513`	RS-232 parity error	RS-232 data reception with parity mismatch	warning
`514`	Command allowed only with RS-232	Attempt to execute RS-232-only command via different interface	warning
`521`	Input buffer overflow	Command input buffer capacity exceeded	error
`522`	Output buffer overflow	Output buffer capacity exceeded	error
`550`	Command not allowed in local	Attempt to execute remote command in local mode	warning
`601`	Front Panel Does not respond	Main controller U17 fails to establish serial communications with front panel controller U7	error
`602`	RAM read/write failed	Checkerboard pattern test (55h and AAh) fails on RAM U15	error
`603`	A/D sync stuck	A/D sync interrupt not recognized; sync pulse timeout occurs	error
`604`	A/D slope convergence failed	ADC integrator positive and negative slope decisions deviate beyond ±10% during 20 ms interval	error
`605`	Cannot calibrate rundown gain	Gain calibration procedure cannot complete due to hardware failure	error
`606`	Rundown gain out of range	Nominal gain between integrating ADC and U17 on-chip ADC exceeds ±10% tolerance	warning
`607`	Rundown too noisy	Gain noise exceeds ±64 lsb's of U17 on-chip ADC after eight repetitions of gain test	warning
`608`	Serial configuration readback failed	Serial configuration data (last 3 bytes) does not match when clocked back into U16	error
`624`	Unable to sense line frequency	LSENCE logic input on U17 not toggling	warning
`625`	I/O processor did not respond	Communication not established between U16 (top board) and U10 (bottom board) via optically isolated serial link	error
`626`	I/O processor failed self-test	Earth referenced processor U10 internal RAM test fails	error
`630`	Fan test failed	Fan current not detected	error
`631`	System DAC test failed	DAC output digital conversion value outside valid range	error
`632`	P6V hardware test failed	Voltage and/or current error amplifiers for +6V circuit not operational	error
`633`	P25V hardware test failed	Voltage and/or current error amplifiers for +25V circuit not operational	error
`634`	N25V hardware test failed	Voltage and/or current error amplifiers for -25V circuit not operational	error
`701`	Cal security disabled by jumper	Calibration security jumper removed during operation	warning
`702`	Cal secured	Calibration mode locked after security code entry	info
`703`	Invalid secure code	Incorrect calibration security code entered	warning
`704`	Secure code too long	Calibration security code exceeds maximum length	warning
`708`	Cal output disabled	Calibration output selection command rejected	warning
`711`	Cal sequence interrupted	Calibration procedure stopped before completion	error
`712`	Bad DAC cal data	DAC calibration data read back differs from written	error
`713`	Bad readback cal data	Readback circuit calibration data verification failed	error
`740`	Cal checksum failed, secure state	Security state data checksum mismatch at startup	error
`741`	Cal checksum failed, string data	Calibration string data checksum mismatch	error
`742`	Cal checksum failed, store/recall data in location 1	Store/recall memory location 1 checksum error	warning
`743`	Cal checksum failed, store/recall data in location 2	Store/recall memory location 2 checksum error	warning
`744`	Cal checksum failed, store/recall data in location 3	Store/recall memory location 3 checksum error	warning
`745`	Cal checksum failed, DAC cal constants	DAC calibration constants checksum mismatch	error
`746`	Cal checksum failed, readback cal constants	Readback calibration constants checksum mismatch	error
`747`	Cal checksum failed, GPIB address	GPIB address storage checksum error at startup	warning
`748`	Cal checksum failed, internal data	Internal calibration data checksum mismatch	error
`800`	P25V and N25V coupled by track system	Tracking coupling detected between positive and negative 25V supplies	error
`801`	P25V and N25V coupled by trigger subsystem	Trigger subsystem couples positive and negative 25V supplies	error
`ERROR`	Error detected during output checkout	Output verification procedure encounters error condition	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.