Test equipment and power supplies · 65xx/66xx series family

Agilent 654xA: troubleshooting and error codes

The ServiceForge knowledge base holds 18 documented symptoms for the Agilent 654xA, with 25 ranked causes, 46 diagnostic checks with test points and expected values, and 59 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 switch turned on but no display response or fan activation

Ranked causes

1. LINE switch not in Off position before startup (common)
2. Power cord not connected (common)
3. Incorrect line voltage fuse installed (occasional)

First check

Verify LINE switch position

Test point: Front panel LINE switch
Expected: Off(0)

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

Calibration: EEPROM initialization after component replacement

EEPROM chip A3U6 or front panel board A3 replaced; supply requires reinitialization with proper constants before calibration

Ranked causes

1. EEPROM chip A3U6 replaced (occasional)
2. Front panel board A3 replaced (occasional)

First check

Run EEPROM initialization program (Figure 3-17)

Test point: Program prompt
Expected: Program pauses to select Initialization (I) or Factory Preset Replacement (F)

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

Calibration: Output current adjustment high voltage

Procedure to set and verify output current control and overcurrent protection limits

Ranked causes

1. Current limit requires programming via keypad (common)
2. Overcurrent protection must be tested and set (common)

First check

Connect short circuit to output terminals

Test point: Output terminals
Expected: Short circuit applied per test diagram (Fig 9)
Tools: Test jumper or wire

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

Calibration: Output voltage adjustment high voltage

Procedure to set and verify output voltage control and overvoltage protection limits

Ranked causes

1. Requires factory-specified voltage programming (common)
2. Overvoltage protection must be tested and set (common)

First check

Set output voltage to 4 volts

Test point: Voltage control and display
Expected: VOLT 4, then 4.000 displayed in meter mode
Tools: Keypad

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

Output protection circuit tripped patient safety

Output voltage or current protection activated; Prot LED illuminated after short circuit or overvoltage condition

Ranked causes

1. Overvoltage protection (OVP) threshold exceeded (common)
2. Overcurrent protection (OCP) activated by output short (common)

First check

Identify protection circuit that tripped

Test point: LED indicators and display
Expected: Prot LED on; display shows OV or OC message

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

Troubleshoot power supply fault high voltage

Power supply does not deliver correct output voltage or current, or exhibits instability

Ranked causes

1. Failed or damaged circuit board (unknown)
2. Defective component on circuit board (unknown)

First check

Verify problem is with power supply and not associated circuit

Test point: Input power and output connections
Expected: Problem isolated to power supply

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

Calibration denied or error code 1

CAL DENIED message on display or error code 1 occurs when attempting calibration via GPIB (models 664xA & 665xA)

Ranked causes

1. INHIBIT CAL jumper installed (common)

First check

Verify INHIBIT CAL jumper position

Test point: INHIBIT CAL jumper location shown in Figure 3-3
Expected: Jumper removed from INHIBIT CAL position

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

Calibration: EEPROM initialization and factory preset restoration

After replacing front panel board A3 or EEPROM chip A3U6, the supply must be reinitialized and calibrated. Program Figure 3-17 must be run twice: once with selection 'I' to initialize, then after calibration with selection 'F' to transfer constants to factory preset locations.

Ranked causes

1. Front panel board A3 or EEPROM chip A3U6 replaced (common)

First check

Run initialization program with selection I

Test point: Power supply at GPIB address 705
Expected: Program pauses for Initialization (I) or Factory Preset Replacement (F) selection

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

Calibration: Front panel board replacement

Recalibration required after replacing A3 Front Panel Board or EPROM chip A3U6

Ranked causes

1. A3 Front Panel Board or EPROM A3U6 replacement (occasional)

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

Calibration: Post-repair output adjustment

Recalibration required after replacing CV/CC DACs, amplifiers, readback circuits, or reference components on A1 Main Board

Ranked causes

1. Component replacement on A1 Main Board (CV/CC DACs, amplifiers, readback circuits) (common)

First check

Verify bias and reference voltages

Test point: See Table 6-3 in Chapter 6 for A2 GPIB board, A2 Isolator Board, and A1 Board test points
Expected: Within specification per service manual

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

Calibration: Transfer calibration constants to Factory Preset locations

Transfer newly obtained calibration constants to EEPROM Factory Cal locations to enable recovery using FACTORY PRESET CAL jumper

Ranked causes

1. Need to back up calibration constants after supply calibration (common)

First check

Run EEPROM program for Factory Preset transfer

Test point: Program prompt
Expected: Program pauses to select Initialization (I) or Factory Preset Replacement (F)

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

Check Fuses indicator blinking high voltage

Check Fuses LED flashes; one or two of three-phase line fuses are open. If all three are open, the indicator does not blink and the unit requires service.

Ranked causes

1. One or two three-phase line fuses open (common)

First check

Observe Check Fuses indicator status

Test point: Front panel Check Fuses LED
Expected: Blinking or steady, indicates fuse condition

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

Check Fuses indicator not blinking with three open fuses caution

Check Fuses indicator does not blink when all three phase fuses are open; unit requires service

Ranked causes

1. All three phase fuses open (occasional)

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

Display shows error message during self-test

LCD displays error code or message instead of normal asterisk pattern or meter mode

Ranked causes

1. Self-test failure detected (unknown)

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

Fan not operating caution

Power switch on but no fan noise or airflow detected

Ranked causes

1. Fan not running during normal self-test (occasional)

First check

Listen and feel for fan operation

Test point: Rear panel grille
Expected: Audible fan noise and/or airflow detected

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

Moisture detected inside unit caution

Dew LED illuminated indicating internal humidity levels exceed safe operating range

Ranked causes

1. High humidity environment or condensation (occasional)

First check

Observe Dew LED status at power-on

Test point: Dew LED indicator (668xA series)
Expected: Dew LED off during normal operation

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

Unit does not power on in high humidity

Power supply fails to turn on when dew forms due to excessive moisture approaching 100%

Ranked causes

1. Excessive moisture (approaching 100% humidity) (common)

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

VOLT or AMPS display shows +OL or –OL

Display indicates out-of-range reading when output voltage or current exceeds meter circuit range

Ranked causes

1. Output voltage or current exceeds meter range (common)

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

Error codes

Code	Meaning	Trigger	Severity
`Addr`	Power supply is addressed for Listen or Talk mode	GPIB system addressing	info
`Cal`	Power supply is in calibration mode	Calibration procedure initiated	info
`CC`	Power supply output in constant current mode	Output shorted or current limit reached	info
`Check Fuses`	Fuse open (668xA series only)	Internal fuse failure detected	error
`Check Fuses`	Power supply fuse is open	Excessive current or internal fault	error
`CV`	Output in constant voltage mode	Output open or load draws minimal current	info
`Dew`	High moisture inside power supply (668xA series only)	Humidity sensor detects excessive moisture	warning
`Dis`	Power supply output is disabled	Output disable command or protection activation	warning
`Dis`	Output disabled or non-functional	Output control failure or protection activation	error
`E1`	FP RAM error	Front panel RAM checksum failure during self-test	error
`E1`	Front panel RAM	Self-test failure	error
`E10`	Secondary 5V ADC read error	5V ADC reading failure during self-test	error
`E10 SEC 5 V`	Secondary interface 5 volt read back test failed	Power-on self-test; also *TST? for 664xA & 665xA models	error
`E11`	Secondary thermistor read error	Thermistor reading failure during self-test	error
`E11 TEMP`	Ambient temperature read back test failed	Power-on self-test; also *TST? for 664xA & 665xA models	error
`E12`	Secondary VDAC/IDAC error	VDAC or IDAC functionality failure during self-test	error
`E12 DACS`	CV or CC DAC tests failed	Power-on self-test	error
`E1 FP RAM`	Front panel RAM test failed	Power-on self-test detection	error
`E2`	FP ROM checksum error	Front panel ROM checksum failure during self-test	error
`E2 FP ROM`	Front panel ROM test failed	Power-on self-test; also *TST? for 664xA & 665xA models	error
`E3`	EEPROM error	EEPROM checksum failure during self-test	error
`E3 EE CHKSM`	Front panel EEPROM checksum test failed	Power-on self-test; also *TST? for 664xA & 665xA models	error
`E4`	Primary external RAM error	Primary XRAM failure during self-test	error
`E4 PRI XRAM`	Primary interface external RAM test failed	Power-on self-test; 664xA & 665xA models only	error
`E5`	Primary internal RAM error	Primary IRAM failure during self-test	error
`E5 PRI IRAM`	Primary interface internal RAM test failed	Power-on self-test; 664xA & 665xA models only	error
`E6`	Primary ROM checksum error	Primary ROM checksum failure during self-test	error
`E6 PRI ROM`	Primary interface ROM test failed	Power-on self-test; also *TST? for 664xA & 665xA models	error
`E7`	GPIB communication error	Serial port communication failure during self-test	error
`E7`	GPIB serial port	Self-test failure	error
`E7 GPIB`	GPIB interface test failed	Power-on self-test	error
`E8`	Secondary RAM error	Secondary RAM failure during self-test	error
`E8 SEC RAM`	Secondary interface RAM test failed	Power-on self-test	error
`E9`	Secondary ROM checksum error	Secondary ROM checksum failure during self-test	error
`E9 SEC ROM`	Secondary interface ROM test failed	Power-on self-test; also *TST? for 664xA & 665xA models	error
`EE WRITE ERR`	EEPROM write failure	Attempt to write to EEPROM during calibration or configuration	error
`Err`	Error message generated from remote operation	Remote control command error	error
`OC`	Overcurrent protection active	Output current exceeds protection threshold	warning
`OCP`	Overcurrent protection circuit is operational	OCP circuit self-test or monitoring	info
`OV`	Overvoltage protection active	Output voltage exceeds limit	error
`Prot`	Protection circuit has shut down the power supply	Overcurrent or overvoltage condition	error
`Prot`	Power supply shutdown due to protection circuit activation	Protection limit exceeded	critical
`Rmt`	Power supply in remote control mode	Remote control enabled or GPIB addressed	info
`SBUF FULL`	Serial buffer failure due to full condition	Serial buffer remains full; data not being processed	warning
`SBUF OVERRUN`	Serial buffer failure due to overrun	Serial buffer exceeded capacity during reception	warning
`SBUV FULL`	Serial buffer overflow	Message too long for buffer capacity	warning
`SECONDARY DN`	Serial data line failure on main board or isolator board	Secondary interface communications loss	error
`SERIAL DOWN`	Serial data line failure on GPIB or isolator board	Communications failure during operation	error
`SERIAL DOWN`	GPIB/front panel communication failure	GPIB unable to communicate with front panel	error
`SERIAL TIMEOUT`	Serial data line failure on GPIB or isolator board	Communications timeout during operation or self-test	error
`Shift`	Shift key has been pressed	Shift key (blue unlabeled key below Recall) pressed	info
`Shift`	Shift key pressed (blue unlabeled key below Recall)	Shift key depression detected	info
`SRQ`	Power supply requesting service from controller	Service request condition detected	warning
`STK OVERFLOW`	Front panel stack overflow	Stack buffer exceeded during front panel operation	error
`UART FRAMING`	UART byte framing error	UART received byte with framing error	warning
`UART OVERRUN`	UART failed due to input buffer overrun	Serial data arrival faster than processor can handle	warning
`UART PARITY`	UART failed due to parity error	Serial communications parity check failure	error
`UART PARTY`	UART byte parity error	Serial communication error	error
`Unr`	Output voltage/current not regulated to setpoint	Output not in CV or CC mode	warning

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.