Test equipment DC power supplies · E36xx series family

Agilent E3633A: troubleshooting and error codes

The ServiceForge knowledge base holds 64 documented symptoms for the Agilent E3633A, with 91 ranked causes, 103 diagnostic checks with test points and expected values, and 64 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

Unit performs automatic self-tests (checks 601-604, 624-632) upon power-on. Test failures prevent normal operation.

Ranked causes

1. Front panel controller communication failure (test 601) (unknown)
2. RAM read/write error (test 602) (unknown)
3. A/D sync pulse not recognized (test 603) (unknown)
4. A/D slope convergence out of range (test 604) (unknown)
5. Rundown gain calibration failure (test 605) (unknown)

First check

Front panel controller communication

Test point: U19 and U1 serial interface
Expected: Bidirectional communication established

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Bias supplies problems caution

Bias supply voltages out of specification or unstable

Ranked causes

1. Regulator input voltage insufficient (occasional)
2. Circuit overload pulling down bias supplies (occasional)
3. Local bias supply inactive (occasional)
4. AC oscillations on bias supplies (rare)

First check

+5V Floating bias supply voltage

Test point: U10 pin 2
Expected: +4.75 V to +5.25 V, +/-0.25 V
Tools: Digital multimeter

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

Unit does not power on high voltage

Power supply is completely inoperative, no display or output

Ranked causes

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

First check

AC power cord connection

Test point: Power inlet connector
Expected: Power cord fully inserted and seated

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 caution

Power supply does not turn on or respond to front-panel power switch

Ranked causes

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

First check

Verify AC power cord connection

Test point: power cord to power supply
Expected: AC power cord connected

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

Output ripple and noise exceeds limit

Peak-to-peak or rms voltage ripple and noise outside specification in frequency range 20 Hz to 20 MHz

Ranked causes

1. Output filter capacitors degraded or missing (common)
2. Common mode noise coupled into measurement (occasional)
3. Switching supply feedback loop oscillation (occasional)

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

Power supply fails self-test

Unit powers on but fails internal self-test diagnostics

Ranked causes

1. Incorrect power-line voltage selected (common)
2. Load connected during self-test (occasional)
3. Terminal connections not removed during self-test (occasional)

First check

Power-line voltage setting verification

Test point: Voltage selector
Expected: Set to correct input voltage (100, 115, or 230 Vac)

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

Unit fails self-test

Unit fails internal self-test upon startup or manual execution

Ranked causes

1. Incorrect power-line voltage setting (common)
2. Terminal connections present during self-test (common)
3. DAC U22 failure on PC board (occasional)

First check

Verify correct power-line voltage setting

Test point: voltage selector switch
Expected: Matches input voltage

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

Calibration: Constant Current (CC) Programming and Readback Accuracy

Verify that current programming and GPIB or RS-232 readback functions are within specifications; readback values over remote interface should match front panel display.

Ranked causes

1. Current monitoring resistor accuracy or measurement setup (common)
2. Full-range current accuracy (common)

First check

Setup monitoring resistor and verify zero current condition

Test point: Current monitoring resistor (RM)
Expected: 0 A ± 10 mA, ±10 mA
Tools: Digital voltmeter, 0.01 Ω resistor

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

Full voltage output reading incorrect

Digital voltmeter reading at full rated voltage setting is outside tolerance, or remote readback value differs from expected

Ranked causes

1. Voltage regulation circuit fault (common)
2. Remote readback accuracy degraded (occasional)

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

Line regulation exceeds limit caution

Output voltage change when AC input varies from low to high line voltage exceeds specified tolerance

Ranked causes

1. Input filter or holdup capacitor degraded (occasional)
2. Voltage regulator feedback network drift (common)

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

Load regulation exceeds limit

Output voltage change from full load to no load exceeds specified tolerance

Ranked causes

1. Voltage regulation loop gain insufficient (common)
2. Load sense line disconnected or high impedance (occasional)

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

Overcurrent condition triggered (OCP TRIPPED)

OCP annunciator blinks and OCP TRIPPED message appears on display when output current exceeds trip level

Ranked causes

1. Output current exceeded OCP trip point (common)
2. External voltage source (e.g., battery) connected to output (occasional)

First check

Verify OCP annunciator blinking and OCP TRIPPED message

Test point: Display screen and OCP annunciator LED
Expected: OCP annunciator flashing, OCP TRIPPED message displayed

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

Transient response time exceeds limit

Recovery time after load transient exceeds 50 µsec to settle within 15 mV of nominal voltage

Ranked causes

1. Transient response compensation network incorrect (common)
2. Regulation loop bandwidth too low (occasional)

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

Unit reports errors 740 to 750

Unit displays error codes 740 to 750 during operation or startup

Ranked causes

1. Power interrupted during calibration (occasional)
2. Hardware failure (occasional)

First check

Power cycle and recalibrate

Test point: unit state
Expected: Unit recalibrated and error cleared

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

Zero voltage output reading incorrect

Digital voltmeter reading at zero volt setting is outside tolerance, or remote readback value differs from front panel display

Ranked causes

1. Voltage programming error (common)
2. Remote interface calibration offset (occasional)

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

A/D converter slope convergence failed

ADC integrator slope decisions do not balance, indicating measurement accuracy degradation

Ranked causes

1. ADC integrator not producing balanced positive and negative slope decisions (unknown)

First check

ADC integrator slope balance during 20 ms interval

Test point: ADC integrator input amplifier
Expected: Equal positive and negative slope decisions within ±10%, ±10%

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

A/D converter sync signal not recognized

A/D converter sync pulse fails to latch value in slope counters, causing measurement system failure

Ranked causes

1. A/D sync pulse not latching or timeout occurring (unknown)

First check

A/D sync pulse recognition and latch operation

Test point: U19, U20 A/D converters
Expected: Sync interrupt recognized, slope counters latch successfully before timeout

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

A/D slope convergence failed (Test 604)

ADC integrator does not produce balanced positive and negative slope decisions within tolerance

Ranked causes

1. Input amplifier or ADC integrator circuit drift or component failure (unknown)

First check

Measure ADC slope decision balance

Test point: ADC integrator output, 10 V range, MZ state
Expected: Positive and negative slope decisions balanced within ±10% over 20 ms interval percent tolerance

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

A/D sync stuck (Test 603)

A/D converter sync interrupt not recognized or timeout occurs

Ranked causes

1. A/D sync pulse circuit failure in U19 or U20 (unknown)

First check

Verify A/D sync pulse issued and interrupt recognized

Test point: U19, U20 sync line
Expected: Sync interrupt recognized without timeout within 20 ms window

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

Calibration: CC Load Effect

Current load regulation: maximum current change under load variation must be within limits

Ranked causes

1. Excessive current load regulation variation (unknown)

First check

Vary load resistance under constant current

Test point: Output terminals
Expected: E3633A: <2.25 mA change; E3634A: <0.95 mA change, E3633A <2.25 mA; E3634A <0.95 mA

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

Calibration: CC PARD Common Mode

Constant current ripple and noise in common mode must be within specification

Ranked causes

1. Excessive current ripple in common mode (unknown)

First check

Measure common mode current ripple

Test point: Output terminals (differential measurement)
Expected: <1.5 µA rms, <1.5 µA rms
Tools: Differential oscilloscope probe

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Calibration: CC PARD Normal Mode

Constant current ripple and noise in normal mode must be within specification

Ranked causes

1. Excessive current ripple in normal mode (unknown)

First check

Measure output current ripple (normal mode)

Test point: Output terminals or current sense resistor
Expected: <2 mA rms, <2 mA rms
Tools: Oscilloscope 20 MHz bandwidth

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

Calibration: CC Programming Accuracy

Current output programming accuracy at 0A and full scale must meet specification limits

Ranked causes

1. Out-of-specification current calibration (unknown)

First check

Measure output current at 0A

Test point: Output terminals via ammeter or shunt
Expected: +0.0100 A to -0.0100 A, +/-0.0100 A

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

Calibration: CC Readback Accuracy

Current readback accuracy verification at 0A and full scale

Ranked causes

1. Out-of-specification current readback (unknown)

First check

Measure current readback at 0A

Test point: Output terminals; compare to front panel display
Expected: IO +0.0050 A to IO -0.0050 A, +/-0.0050 A from measured IO

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

Calibration: CC Source Effect

Current line regulation: maximum current change with input line variation must be within limits

Ranked causes

1. Excessive current line regulation variation (unknown)

First check

Vary AC input line +/-10%

Test point: Output current measurement
Expected: E3633A: <2.25 mA change; E3634A: <0.95 mA change, E3633A <2.25 mA; E3634A <0.95 mA

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

Calibration: Common Mode Current Noise

Measure ac current component between output lines and chassis ground to verify it does not exceed specification limits.

Ranked causes

1. Out-of-specification common mode current noise (unknown)

First check

Set up measurement circuit with 100 kΩ resistor and 2200 pF capacitor in parallel between (-) terminal and chassis ground

Test point: (-) terminal to chassis ground
Expected: Proper circuit connection

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

Calibration: Constant Current Load Effect (Load Regulation)

Measure change in output current when load varies from full rated output voltage to short circuit in constant current mode.

Ranked causes

1. Load regulation at full-rated to short-circuit transition (common)

First check

Measure output current at full-rated voltage

Test point: Current monitoring resistor (RM)
Expected: Full rated value
Tools: Digital voltmeter, electronic load, 0.01 Ω resistor

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

Calibration: Constant Current PARD (Ripple and Noise)

Measure periodic and random deviations (ripple and noise) in output current in frequency range 20 Hz to 20 MHz with supply in constant current operation.

Ranked causes

1. Ripple and noise measurement setup and verification (common)

First check

Setup load and measurement instruments for PARD test

Test point: Current monitoring resistor (RM)
Expected: RMS ripple and noise per specification
Tools: RMS voltmeter, load resistor 0.4 Ω or 3.5 Ω

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

Calibration: Constant Current Source Effect (Line Regulation) caution

Measure change in output current resulting from AC line voltage variation from 10% below to 10% above nominal input voltage in constant current mode.

Ranked causes

1. Line regulation at minimum and maximum AC input voltage (common)

First check

Setup transformer and measure current at low line voltage

Test point: Current monitoring resistor (RM)
Expected: Full rated output current at minimum AC input
Tools: Digital voltmeter, variable transformer, electronic load

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

Calibration: Current and OCP

Software-based current output and overcurrent protection calibration using GPIB interface, DMM measuring across 0.001 ohm shunt

Ranked causes

1. Current calibration required at minimum, middle, and maximum levels (common)

First check

Verify DAC DNL error correction completed

Test point: Syst:Err?
Expected: 0

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

Calibration: CV Load Effect

Load regulation verification: maximum voltage change under load variation must be within limits

Ranked causes

1. Excessive load regulation variation (unknown)

First check

Vary load from zero to full rated current

Test point: Output terminals
Expected: E3633A: <4 mV change; E3634A: <7 mV change, E3633A <4 mV; E3634A <7 mV

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

Calibration: CV PARD

Power supply ripple and noise (PARD) verification in normal and common modes

Ranked causes

1. Excessive output ripple or noise (unknown)

First check

Measure output ripple and noise

Test point: Output terminals
Expected: Normal mode: <3 mV p-p; E3633A: <350 µV rms; E3634A: <500 µV rms, <3 mV p-p; E3633A <350 µV rms; E3634A <500 µV rms
Tools: Oscilloscope 20 MHz bandwidth

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

Calibration: CV Programming Accuracy

Voltage output programming accuracy at 0V and full scale must meet specification limits for model verification

Ranked causes

1. Out-of-specification voltage calibration (unknown)

First check

Measure DVM reading at 0V output

Test point: Output terminals
Expected: +0.0100 V to -0.0100 V, +/-0.0100 V

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

Calibration: CV Readback Accuracy

Voltage readback accuracy measurement verification at 0V and full scale

Ranked causes

1. Out-of-specification readback accuracy (unknown)

First check

Measure readback accuracy at 0V

Test point: Output terminals; compare to front panel display
Expected: DVM +0.0050 V to DVM -0.0050 V, +/-0.0050 V from DVM

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

Calibration: CV Source Effect

Line regulation verification: maximum voltage change with input line variation must be within limits

Ranked causes

1. Excessive line regulation variation (unknown)

First check

Vary AC input line +/-10%

Test point: Output terminals
Expected: E3633A: <4 mV change; E3634A: <7 mV change, E3633A <4 mV; E3634A <7 mV

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

Calibration: Electronic correction factors

Procedure to calibrate output voltage and current using closed-case electronic calibration with input reference values

Ranked causes

1. Calibration due per maintenance interval (unknown)

First check

Determine calibration interval requirement

Test point: Application accuracy specification
Expected: 1-year interval adequate for most applications; do not extend beyond 1 year

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

Calibration: Load Transient Response Time

Verification that output settles within specified time when load changes

Ranked causes

1. Slow transient response (unknown)

First check

Apply step load change

Test point: Output terminals
Expected: Settling time <50 µsec, <50 µsec
Tools: Oscilloscope

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

Calibration: Performance Verification

Verify power supply operates within performance specifications listed in chapter 1. Two levels: Self-Test (internal verification) and Performance Verification Tests (specification compliance).

Ranked causes

1. Performance drift or component degradation after repair (unknown)

First check

Power-on self-test result

Test point: Front panel display
Expected: PASS displayed

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

Calibration: Unsecure power supply with security code

Power supply is [withheld] (E3633A) or [withheld] (E3634A). Technician must enter correct code to access calibration mode from front panel.

Ranked causes

1. Power supply in secured state at factory (common)

First check

Verify calibration mode activated

Test point: Front panel display
Expected: CAL MODE message displayed after long beep

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

When security code is forgotten, jumper method allows unsecuring by temporarily bridging JP5 pads inside unit, then entering any code.

Ranked causes

1. Security code forgotten or lost (rare)

First check

Disconnect power and open enclosure

Test point: Power supply exterior
Expected: Power cord disconnected, all loads removed, instrument cover removed

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

Calibration: Voltage and OVP

Software-based voltage output and overvoltage protection calibration using GPIB interface with DMM and 0.001 ohm current shunt

Ranked causes

1. Voltage calibration required at minimum, middle, and maximum levels (common)

First check

Unsecure power supply for calibration

Test point: Cal:Sec:Stat?
Expected: Response should not contain '1'

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

Cannot calibrate rundown gain (Test 605)

Procedure fails to complete due to hardware failure; integrating ADC to U19 on-chip ADC gain mismatch

Ranked causes

1. Integrating ADC or U19 on-chip ADC component failure or gain circuit drift (unknown)

First check

Verify ADC gain calibration can complete

Test point: Integrating ADC to U19 ADC interface
Expected: Gain calibration procedure completes without timeout or hardware error

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

Complete self-test initiated

User holds any front panel key except Error key for more than 5 seconds while powering on; unit beeps when test starts

Ranked causes

1. Operator initiates extended diagnostics (common)

First check

Confirm unit beeps when test starts

Test point: Audible output
Expected: Single beep at start of complete self-test

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

Display returns to OCP TRIPPED message after timeout

After exiting OCP menu, display reverts to OCP TRIPPED message after several seconds instead of remaining in normal mode

Ranked causes

1. Overcurrent condition not fully cleared (common)

First check

Ensure OCP clear mode is reached and completed

Test point: Display screen
Expected: DONE message displayed, OCP annunciator stops blinking

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

Fan cooling circuit failure caution

Fan does not operate or fan current not detected, risking overtemperature condition

Ranked causes

1. Fan current not detected, fan stopped or circuit open (common)

First check

Fan current detection at fan drive circuit

Test point: Fan drive output
Expected: Fan current flowing, fan spinning

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

I/O processor communication failure

Communications cannot be established between main controller and front panel processor through optical link

Ranked causes

1. Optically isolated serial link (U2, U5) failure (unknown)

First check

Bidirectional serial communication through optical isolators

Test point: U2, U5 optoisolators, serial data signals
Expected: Communication established successfully both directions

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

I/O processor internal RAM test failed

Front panel processor U1 internal RAM test does not pass, indicates processor memory or logic failure

Ranked causes

1. U1 internal RAM failure or processor logic error (unknown)

First check

U1 internal RAM and processor self-test execution

Test point: U1 front panel processor
Expected: Internal RAM test passes without error

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

Line frequency detection failed

Power supply cannot sense AC line frequency, system defaults to 50 Hz operation

Ranked causes

1. LSENCE logic input signal not toggling or not detected (unknown)

First check

LSENCE logic input signal presence and toggling

Test point: U19 LSENCE input
Expected: Logic input toggling at line frequency

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

OCP annunciator not enabled after setting trip level

OCP annunciator fails to turn on after completing OCP menu configuration steps

Ranked causes

1. OCP circuit not properly enabled in menu (common)

First check

Verify OCP menu entry and trip level setting

Test point: Display screen
Expected: LEVEL message displayed with trip level value

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

Overvoltage protection trip cleared by trip level adjustment

OVP condition resolved by raising OVP trip level above current output voltage

Ranked causes

1. Output voltage at or above OVP trip level (common)

First check

Verify OVP trip level is raised above output voltage

Test point: OVP trip level display
Expected: OVP trip level > current output voltage

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

Overvoltage protection trip cleared by voltage adjustment

OVP condition resolved by lowering output voltage below trip point

Ranked causes

1. Output voltage exceeds OVP trip point (common)

First check

Verify output voltage is below OVP trip point

Test point: Output display
Expected: Output voltage < OVP trip level setting

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

Overvoltage protection trip occurs

Output voltage reaches or exceeds OVP trip level; power supply output drops to near zero, OVP annunciator blinks, CC annunciator turns on, 'OVP TRIPPED' message displayed

Ranked causes

1. External voltage source connected to output (e.g., battery) (occasional)

First check

Verify external voltage source presence

Test point: Output terminals
Expected: No external voltage source connected

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

Power supply does not respond to front panel input

Front panel keys do not function or are unresponsive to user commands

Ranked causes

1. Front panel controller U1 communication failure (unknown)

First check

Verify front panel controller U1 responds and display segments activate

Test point: U1 front panel controller
Expected: All display segments illuminated, serial communication established both directions

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

RAM read/write failed (Test 602)

Unit fails memory test on RAM U14; error readable only from remote interface

Ranked causes

1. RAM U14 defective or communication error (unknown)

First check

Write and read test patterns to RAM U14

Test point: RAM U14 address range
Expected: 55h and AAh patterns read back correctly from all addresses

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

RAM read/write failure

Memory test fails during self-test, indicates RAM data corruption or hardware failure

Ranked causes

1. RAM U14 defective or data path corrupted (unknown)

First check

Read/write test to RAM U14 with checker board pattern

Test point: U14 RAM
Expected: 55h and AAh pattern written and read back successfully at all addresses

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

Rated output voltage not achievable

Front-panel voltmeter does not respond to knob control or voltage cannot be adjusted from zero to maximum rated value (8.0 V for E3633A or 25.0 V for E3634A)

Ranked causes

1. Knob control not responding or voltage adjustment mechanism failure (unknown)

First check

Verify power supply is turned on and outputs enabled

Test point: Front panel OFF annunciator and 8V/25V annunciator
Expected: OFF annunciator off; 8V or 25V, OVP, OCP, and CV annunciators lit

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Rated output voltage not achievable (E3634A)

Front-panel voltmeter does not respond to knob control or voltage cannot be adjusted from zero to 25.0 volts maximum rated value

Ranked causes

1. Knob control not responding or voltage adjustment mechanism failure (unknown)

First check

Verify power supply is turned on and outputs enabled

Test point: Front panel OFF annunciator and 25V annunciator
Expected: OFF annunciator off; 25V, OVP, OCP, and CV annunciators lit

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

Rundown gain calibration cannot complete

Rundown gain calibration procedure cannot finish, indicates hardware failure in measurement circuit

Ranked causes

1. Hardware failure prevents rundown gain calibration completion (unknown)

First check

Rundown gain calibration execution

Test point: Integrating ADC, U19 on-chip ADC
Expected: Calibration completes without timeout or error

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Rundown gain out of specification

Measured gain between integrating ADC and U19 on-chip ADC exceeds tolerance limits

Ranked causes

1. Gain measured outside ±10% tolerance (unknown)

First check

Rundown gain measurement

Test point: Integrating ADC to U19 ADC signal path
Expected: Gain within ±10% of nominal value, ±10%

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Rundown gain repeatability excessive

Gain measurement noise exceeds specification, causing unstable measurement accuracy

Ranked causes

1. Gain noise exceeds ±64 LSB specification (unknown)

First check

Rundown gain noise measurement (8 repeated tests)

Test point: U19 on-chip ADC output
Expected: Gain noise less than ±64 LSB, ±64 LSB

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

More symptoms

Self-Test: Complete verification
Serial configuration readback failed
System DAC hardware not functional
Voltage or current error amplifier not operational

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Error codes

Code	Meaning	Trigger	Severity
`-330`	Self-test failed	Self-test routine execution	error
`-350`	Too many errors	Error threshold exceeded during operation	error
`501`	Isolator UART framing error	Serial communication with isolator circuit	error
`502`	Isolator UART overrun error	Isolator serial input buffer overflow	warning
`511`	RS-232 framing error	Serial port RS-232 communication	error
`512`	RS-232 overrun error	RS-232 input buffer overflow	warning
`513`	RS-232 parity error	RS-232 serial data reception	error
`514`	Command allowed only with RS-232	Non-RS-232 interface command attempt	error
`521`	Input buffer overflow	Input buffer capacity exceeded	error
`522`	Output buffer overflow	Output buffer capacity exceeded	error
`550`	Command not allowed in local	Remote command in local mode	error
`601`	Front panel controller communication failure	Main controller U19 cannot establish serial communications with U1 on front panel board	error
`601`	Front Panel Does not respond	Main controller U19 cannot establish serial communication with front panel controller U1	error
`602`	RAM read/write failed	Checkerboard pattern test (55h and AAh) fails on RAM U14	error
`603`	A/D sync signal stuck	A/D sync interrupt not recognized or timeout occurs before sync completes	error
`604`	A/D slope convergence failed	ADC slope decisions not balanced within ±10% in 10 V range	error
`605`	Cannot calibrate rundown gain	Rundown gain calibration procedure cannot complete due to hardware failure	error
`606`	Rundown gain out of range	Measured gain between integrating ADC and U19 on-chip ADC outside ±10% tolerance	warning
`607`	Rundown gain too noisy	Gain noise from repeated tests exceeds ±64 LSB specification on U19 ADC output	warning
`608`	Serial configuration readback failed	3-byte serial configuration data does not match after transmission through U23	error
`624`	Unable to sense line frequency	LSENCE logic input to U19 not toggling or not detected	warning
`625`	I/O processor did not respond	Communication not established between U19 and U1 through optically isolated link in either direction	error
`626`	I/O processor failed self-test	U1 internal RAM test fails or processor logic error detected during execution	error
`630`	Fan test failed	Fan current not detected at power-on self-test, fan not running	critical
`631`	System DAC test failed	DAC output readback after reference voltage test outside valid range	error
`632`	Hardware test failed (error amplifier failure)	Voltage and/or current error amplifier not operational or both amplifiers not responding	critical
`701`	Cal security disabled by jumper	Calibration startup check	info
`702`	Cal secured	Calibration access attempt when secured	warning
`703`	Invalid secure code	Calibration security code entry	error
`704`	Secure code too long	Security code entry during calibration	error
`705`	Cal aborted	Calibration routine interrupted	warning
`708`	Cal output disabled	Calibration output verification	error
`712`	Bad DAC cal data	DAC calibration data readback	error
`713`	Bad readback cal data	Calibration readback verification	error
`714`	Bad OVP cal data	Overvoltage Protection calibration data check	error
`715`	Bad OCP cal data	Overcurrent Protection calibration data verification	error
`716`	Bad DAC DNL error correction data	DAC Differential Nonlinearity correction data check	error
`717`	Cal OVP or OCP status enabled	Calibration verification check	warning
`718`	Gain out of range for gain error correction	Gain calibration or correction routine	error
`740`	Cal checksum failed, secure state	Calibration security checksum verification	critical
`741`	Cal checksum failed, string data	Calibration string data checksum verification	critical
`742`	Cal checksum failed, store/recall data in location 0	Calibration storage location 0 checksum check	critical
`743`	Cal checksum failed, store/recall data in location 1	Calibration storage location 1 checksum verification	critical
`744`	Cal checksum failed, store/recall data in location 2	Calibration storage location 2 checksum check	critical
`745`	Cal checksum failed, store/recall data in location 3	Calibration storage location 3 checksum verification	critical
`746`	Cal checksum failed, DAC cal constants	DAC calibration constants checksum check	critical
`747`	Cal checksum failed, readback cal constants	Readback calibration constants checksum verification	critical
`748`	Cal checksum failed, GPIB address	GPIB address calibration checksum check	critical
`749`	Cal checksum failed, internal data	Internal calibration data checksum verification	critical
`750`	Cal checksum failed, DAC DNL error correction data	DAC DNL correction data checksum check	critical
`CHANGED`	OVP settings have been successfully updated	User modifies OVP trip level and exits OVP menu	info
`CHANGED`	OCP settings have been modified and new trip level is now active	User changes OCP trip level setting and exits OCP menu	info
`DONE`	Overcurrent condition has been successfully cleared and power supply has returned to normal operation	User completes OCP clear procedure and presses confirmation key	info
`ERROR`	Error detected during output checkout procedure	Detected during steps 1-6 of rated current output checkout	warning
`Error`	Incorrect security code entered or jumper left connected during unsecure attempt	Invalid security code entry from front panel; JP5 jumper not removed after unsecure operation	error
`NO CHANGE`	OCP settings were not modified during menu session	User exits OCP menu without changing trip level value	info
`OCP TRIPPED`	Overcurrent protection circuit has activated due to output current exceeding the programmed trip level	Output current exceeds OCP trip point setting	warning
`OVP TRIPPED`	Overvoltage protection circuit has activated due to output voltage reaching or exceeding the OVP trip level	Output voltage rises to or above the programmed OVP trip level	warning
`SECURED`	Power supply is in secured state and calibration access is blocked	Power supply powered on while security code protection is active	warning
`Test 601`	Front panel communication failed	Serial link between U19 and U1 does not establish bidirectional communication	error
`Test 602`	RAM read/write failed	Checker board pattern (55h, AAh) not read back correctly from U14	error
`Test 603`	A/D sync stuck	Sync interrupt not recognized or timeout during A/D sync pulse latch	error
`Test 604`	A/D slope convergence failed	Positive and negative slope decisions not balanced within ±10% in 20 ms interval	error
`Test 605`	Cannot calibrate rundown gain	Gain calibration procedure fails to complete due to hardware error	error

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