Test equipment electronic loads

Agilent 6050A: troubleshooting and error codes

The ServiceForge knowledge base holds 51 documented symptoms for the Agilent 6050A, with 97 ranked causes, 113 diagnostic checks with test points and expected values, and 20 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

DAC circuits not generating SLEW signal high voltage

Analog SLEW signal not produced by combined outputs from main DAC/amplifier (U320/U326) and transient DAC/amplifier (U321/U325); signal controls input power stages

Ranked causes

1. Chip select IC U304 malfunction (unknown)
2. Status readback IC U303 malfunction (unknown)
3. EEPROM decoder U341 malfunction (unknown)
4. Transient DAC/amplifier U321/U325 failure (unknown)
5. Main DAC/amplifier U320/U326 failure (unknown)

First check

Measure signature at U304 pins 6 and 16 for +5V rail

Test point: U304-6,16
Expected: 1CAU

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

Overpower circuit fault caution

Overpower circuit not responding correctly to input voltage/current; power limitation not activating or deactivating properly

Ranked causes

1. U10 comparator failure (occasional)
2. R142 summing resistor pack open or incorrect value (occasional)
3. RT2 temperature monitor or U327 failure (occasional)
4. +12V reference voltage low or absent (occasional)

First check

Verify +12V reference voltage present

Test point: +12V reference input
Expected: +12V ±tolerance
Tools: DMM

Fans not running or not changing speed high voltage

Fan #1 and/or Fan #2 do not operate or do not respond to speed control commands; fans run continuously at maximum speed

Ranked causes

1. Fan motor defective or fan connector loose (common)
2. Fan speed control circuit failure; U245 or U233 bit logic error (occasional)
3. Module heatsink temperature sensor failure or excessive heat condition (occasional)

First check

Verify fan connector power and signal at fan motor

Test point: Fan connector pins
Expected: Waveform present matching U243-1 normal power-on waveform
Tools: Oscilloscope

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

Front panel display remains blank at power-on

No display output when unit powers on; may indicate RAM, ROM, or internal timer failure in primary microprocessor

Ranked causes

1. Primary microprocessor U203 RAM failure (occasional)
2. Primary microprocessor U203 ROM failure (occasional)
3. Primary microprocessor U203 internal timer failure (occasional)

First check

Measure square wave on SA_GATE line

Test point: TP201-8
Expected: 10Hz, 100Hz, 1KHz, or no square wave
Tools: Oscilloscope or logic probe

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

Incorrect slew rate waveform output

Electronic Load slew circuit produces incorrect waveform output when various slew rates programmed. Waveforms checked to verify slew circuit switches operation.

Ranked causes

1. SDB0-7 data inputs or SLW signal outputs faulty (occasional)
2. Slew circuit amplifier or switch (U346, U317) defective (occasional)
3. CC/CV control circuit malfunction (rare)

First check

Verify SA waveforms on Figure 3-3

Test point: SA waveform output
Expected: Waveforms match Figure 3-3 specifications

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

Input power stage malfunction

One or more of four/eight/sixteen input power stages not operating correctly; error amplifier waveform absent or incorrect at stage output

Ranked causes

1. Specific input power stage defective (common)
2. Multiple stages defective or shared supply problem (occasional)
3. SENSE switch incorrectly set (occasional)

First check

Enable SA mode and verify error amplifier waveform

Test point: Error amplifier output in each input power stage
Expected: Waveform as shown in Figure 3-6

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

Input power stage not functioning in specific module caution

One of four, eight or sixteen identical input power stages (FET Q2, monitor amplifier U6, error amplifier U5) is defective or producing incorrect waveforms

Ranked causes

1. Power FET (Q2) failure or open (common)
2. Fuse F5 or F13 open (stage Q2D) (common)
3. Error amplifier (U5) or monitor amplifier (U6) failure (occasional)

First check

Verify error amplifier output waveform in SA mode

Test point: Error amplifier output of defective stage, refer to Power Board schematic for pin location
Expected: Waveform as shown in Figure 3-6
Tools: Oscilloscope

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

Overcurrent circuit limiting maximum input current abnormally

Load unable to sink expected maximum current; circuit limits sink capability below normal range

Ranked causes

1. Input voltage below 6.3 V (model dependent) (common)
2. Overvoltage (OV) circuit activation at high input voltage (occasional)
3. Delayed bias voltage (-15Vx) not present on startup (occasional)

First check

Verify input voltage and measure at test point (per Table 3-3)

Test point: Test points specified in Table 3-3
Expected: Refer to Table 3-3 measurement conditions and readings

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

Overcurrent circuit malfunction caution

Maximum current limit not functioning correctly across input voltage range or power conditions

Ranked causes

1. Diode D53 failure (occasional)
2. Diode D54 failure (occasional)
3. Amplifier U14 or transistor Q11/Q12 failure (occasional)

First check

Measure voltage at U14-6 with input voltage at or below 6.3V

Test point: U14-6
Expected: approximately -7 volts

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

Secondary microprocessor U301 internal ROM failure (Error -102)

Secondary microprocessor ROM selftest failure or power board disconnection; secondary processor ROM or power supply defect

Ranked causes

1. Power board disconnected (common)
2. Thermistor RT2 missing or open circuit (occasional)
3. U301 internal ROM defect (rare)

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

Signature analysis testing needed for troubleshooting caution

Microprocessor-based circuit faults isolated using signature analyzer to compress bit streams into four-character signatures for comparison against known correct values

Ranked causes

1. Faulty component in digital circuit producing incorrect signature (common)
2. Shorted pin or node to Vcc or ground (occasional)
3. Two pins shorted together (occasional)

First check

Take signature at applicable test point using signature analyzer

Test point: Primary test points per Tables 3-4 through 3-9; secondary per Tables 3-10 through 3-14
Expected: Four-character signature matching reference table for applicable component (U203, U205, U206, U301)

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

Transient generator produces incorrect or no output frequency

Transient mode enabled but output frequency at U314-7 is wrong or absent; expected factory default is 1 kHz at 50% duty cycle

Ranked causes

1. Incorrect FSEL inputs or U311 output (common)
2. U312 or U313 output malfunction (occasional)
3. Transient trigger circuit failure (occasional)

First check

Enable transient mode and verify TRANS_EN signal condition

Test point: TRANS_EN signal
Expected: Per Table 3-3 (not provided in excerpt)

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

Unit fails power-on self-test high voltage

At power-on, front panel LCD displays error number or message. Unit does not complete normal initialization. Load input remains disabled.

Ranked causes

1. Primary circuit failure (GPIB interface or primary processor) (unknown)
2. Secondary circuit or module failure (unknown)
3. AC input or bias supply failure (unknown)

First check

Observe power-on display

Test point: Front panel LCD
Expected: Normal turn-on self-test indication or error code

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

Unit fails selftest with error 105-108 at turn-on

System displays error code 105-108 during power-on self-test sequence

Ranked causes

1. IMON adjustment out of specification (occasional)
2. Switches in U309 not operating properly (occasional)
3. Faulty DAC or amplifier generating incorrect waveform (rare)

First check

Use Signature Analyzer (SA) to diagnose error 105-108

Test point: Test points specified in SA documentation
Expected: Valid signatures per SA mode table
Tools: Signature Analyzer

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

AC line trigger signal not toggling

Waveforms at U243-14 and Q211-11 are incorrect or absent when sending TRIG:SOUR LINE command

Ranked causes

1. Defective GPIB board IC or gate (unknown)
2. Defective Control board IC (unknown)

First check

Measure waveform at U243-14 and Q211-11

Test point: U243-14, Q211-11
Expected: Correct waveform present
Tools: Oscilloscope

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

All input power stages have circuit problems caution

Multiple or all input power stages are failing simultaneously; affects power delivery and load regulation

Ranked causes

1. Common supply voltage or control signal failure (common)
2. SENSE switch S1 not set to LCL for local sensing (occasional)

First check

Verify SENSE switch position

Test point: S1 switch on rear panel
Expected: Set to LCL position if remote sensing not used

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

DAC circuit waveforms incorrect

SA mode waveforms shown in Figure 3-3 are not correct; SLEW signal generation from main and transient DAC/amplifiers affected

Ranked causes

1. Faulty readback DAC U322 data bus lines SD0-7 (common)
2. Faulty main or transient DAC data lines SDB0-7 (common)

First check

Verify SA mode is enabled

Test point: Jumpers TP201 and TP301
Expected: Jumpers connected in SA mode positions

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

EEPROM U342 checksum error (Error -104)

EEPROM checksum failed during selftest; calibration data corrupted or EEPROM defective

Ranked causes

1. EEPROM calibration data corrupted (common)
2. EEPROM U342 data line failure (occasional)

First check

Reprogram and reinitialize EEPROM

Test point: EEPROM U342
Expected: Checksum restored; error -104 does not reappear

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

Module not installed or secondary communication failure (Error -240)

No module installed in mainframe, or communication failure between primary and secondary processor; INPUT DWN message displayed

Ranked causes

1. No module installed in mainframe (common)
2. SRX or STX serial data line failure (occasional)

First check

Verify serial data pulses on SRX and STX lines

Test point: U333-7 (SRX), U334-3 (STX)
Expected: Data pulses toggling between 0V and 5V
Tools: Logic probe

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

Overpower circuit active - power limiting caution

Load operating in overpower condition; power sinking capability limited by thermal or time duration threshold

Ranked causes

1. Overpower condition exists - EPU bit false (common)
2. Overpower condition exists - EPU bit true (common)

First check

Check test points and reference voltage using Table 3-3 conditions

Test point: U17 amplifier, U10 comparators, R142 summing resistor pack, +12V reference
Expected: Values per Table 3-3

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

Overpower detection and load limiting failure caution

Load continues to draw power beyond safe limits or fails to enter overpower protection mode when limits exceeded

Ranked causes

1. Comparator circuit U10 malfunction or output not reaching controller (occasional)
2. Amplifier U12 not summing signals correctly (rare)

First check

Measure comparator U10 output voltage at each of four comparator stages

Test point: U10 outputs (per Figure 3-10)
Expected: Logic high/low transitions when input signals cross threshold
Tools: Oscilloscope, logic probe

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

PROG signal not going negative after startup high voltage

Q11 remains on after startup; PROG stays high; input power FETs remain off

Ranked causes

1. Delayed bias voltage (-15Vx) not present or delayed excessively (occasional)
2. Q12 not turning off when -15Vx arrives (rare)

First check

Measure -15Vx bias voltage after power-on delay (approximately 5-10 seconds)

Test point: -15Vx supply node
Expected: -15 V ±10% after startup delay, ±10%

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

Slew circuit generates incorrect waveforms

SA mode waveforms at oscilloscope are incorrect or do not match expected patterns for slew circuit function

Ranked causes

1. Incorrect SDB0-7 data inputs or SLW signal outputs from U305 (common)
2. Defective amplifier or switch in slew circuit (occasional)

First check

Verify SA waveforms at oscilloscope

Test point: Slew circuit outputs per Figure 3-4
Expected: Waveforms matching SA mode patterns shown in Figure 3-4
Tools: Digital oscilloscope

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

Slew rate waveforms not generated in normal mode

Programmed slew rate waveforms (0.001, 0.5, 2.5 A/µs) are not appearing at oscilloscope after front panel configuration

Ranked causes

1. Slew circuit switches (U317) not operating correctly (common)
2. CC/CV control circuit fault (occasional)

First check

Configure front panel for slew rate testing

Test point: Front panel controls
Expected: MODE=CURR, CURR=5, Tran Level=10, Freq=80, Dcycle=50, Tran on/off=on

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

Transient generator does not perform any functions

Transient generator circuits (U349-U355) are non-functional; unable to switch between load levels or generate HIGH control signal to DAC circuits

Ranked causes

1. Data bus or internal clock failure (common)
2. Defective transient generator IC (U349-U355) (occasional)

First check

Verify 1MHz clock signal at specified pins

Test point: U349-1, U350-1, U351-13, U352-4, U352-12
Expected: 1MHz clock signal present
Tools: Oscilloscope

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

Transient generator malfunction

Transient generator circuits not switching load levels correctly or not producing HIGH control signal

Ranked causes

1. Data bus or internal clock failure (common)
2. Frequency control logic error (occasional)

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

Transient generator toggle or pulse mode not functioning

Toggle and pulse mode operations do not respond to mode commands; output signals absent or incorrect at mode-specific test points

Ranked causes

1. Mode control signal path failure (common)
2. Output stage IC (U349, U350, U351, U352) defect (occasional)

First check

Verify toggle mode control signals

Test point: U349-3, U349-4, U350-3, U349-14, U351-9, U351-11, U351-14, U352-13
Expected: Toggle mode: U349-3=LO, U349-4=HI, U350-3=LO, U349-14=toggling, U351-9/11/14=LO, U352-13=toggling, U351-12=HI
Tools: Logic probe, oscilloscope

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

Transient generator will not change frequency

Pressing TRAN ON and programming transient frequencies does not result in frequency change; unit remains at factory default or incorrect frequency

Ranked causes

1. FSEL input signal loss or corruption (common)
2. Pulse interval timing circuit failure (occasional)

First check

Verify FSEL input logic levels

Test point: U351-1, U351-2, U351-3
Expected: Logic levels per FSEL table for programmed frequency
Tools: Logic probe

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

Unit fails front panel verification tests high voltage

After passing self-test, unit fails verification of load functions. Some functions are not calibrated or not operating properly.

Ranked causes

1. Load function not calibrated (unknown)
2. Load function not operating properly (unknown)

First check

Perform front panel verification procedures

Test point: Load control functions
Expected: All functions operate as specified in Operating Manual Chapter 3

Bus trigger signal not toggling

Trigger signal not generated when using TRIG command or *TRG common command via HPIB

Ranked causes

1. Defective bus trigger circuit on GPIB board (unknown)

First check

Verify READ_TRIG level at power-on

Test point: U210-11 (READ_TRIG)
Expected: High

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

Calibration disable jumper configuration caution

Jumper RTP201 setting to prevent unauthorized calibration commands on primary microprocessor

Ranked causes

1. Unauthorized calibration performed on unit (unknown)

First check

Verify calibration security jumper position

Test point: Primary test header TP201 pins 5 and 6
Expected: Jumper RTP201 installed between pins 5 and 6 for lockout; removed for normal calibration access

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

Calibration: Current Monitor (IMON) circuit

Adjustment of IMON circuit after input power stage component replacement. Connect DMM between test points and adjust potentiometer for correct reading.

Ranked causes

1. Input power stage component replaced (common)

First check

Measure voltage at IMON test points

Test point: J2-1 and J2-3
Expected: 0 ±0.5 millivolts mV, ±0.5 mV
Tools: DMM

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

Calibration: EEPROM initialization

Programming serial EEPROM chip U211 with GPIB address, model number, and factory constants after GPIB board or EEPROM replacement. Run commands in sequence then recalibrate.

Ranked causes

1. GPIB board assembly or EEPROM chip U211 replaced (occasional)

First check

Program EEPROM initialization commands

Test point: Serial port or GPIB interface
Expected: Commands accepted without error

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

Calibration: Overpower circuit signal scaling caution

Verify signal scaling of input voltage and current via resistor network to set correct power limits

Ranked causes

1. Signal scaling resistor values out of tolerance or wrong part installed (occasional)

First check

Measure input voltage signal level at U12 summing amplifier input

Test point: U12 pin (voltage input to amplifier)
Expected: Signal proportional to input voltage per schematic specification
Tools: Multimeter, oscilloscope

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

Excessive input current limiting at power-on

Current limited to lower than normal maximum during power-on even before high voltage reached

Ranked causes

1. SPCLR signal not releasing Q11 properly at end of power-on sequence (rare)

First check

Monitor SPCLR signal and Q11 gate voltage during power-on sequence

Test point: SPCLR input and Q11 base
Expected: SPCLR high during initialization, low after ~100-500 ms; Q11 transitions off

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

External trigger signal not responding

Unit does not respond to external trigger input when TRIG:SOUR EXT is set and TRIG_IN is asserted

Ranked causes

1. Defective external trigger input circuit (unknown)

First check

Verify external trigger input pulse at U207-10

Test point: U207-10
Expected: Pulses when TRIG_IN shorted to common

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

GET function trigger not generating pulses

Trigger pulses not generated when using GET function for group enable trigger

Ranked causes

1. Defective P_TRIG output or firmware gate (unknown)

First check

Verify P_TRIG pulse output

Test point: U208-12 (P_TRIG)
Expected: Pulses high

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

INPUT DWN message repeated on display

INPUT DWN or INPUT DWN 1 message appears at power-on; secondary communication or AC power issue

Ranked causes

1. Line switch cycled repetitively or abnormal line conditions (common)

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

Internal timer trigger signal not pulsing

Timer-based trigger pulses not generated when sending TRIG:SOUR TIM command

Ranked causes

1. Defective timer circuit on GPIB board (unknown)

First check

Verify timer enable signal

Test point: U228-12 (TRIG_EN)
Expected: Goes high

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

Load power mode selection (normal vs. extended)

Circuit selects between normal and extended power ranges via EPC_EN signal; extended mode requires external power connection

Ranked causes

1. External power unavailable or not connected (common)

First check

Query EPU (Extended Power Unavailable) bit status

Test point: Status register bit 9
Expected: EPU bit false when extended power available; true when unavailable

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

Main DAC circuit zero or full scale out of tolerance (Error -105, -106)

Main DAC U320/U326 zero point or full scale calibration exceeds tolerance limits during selftest

Ranked causes

1. Main DAC circuit calibration error or component failure (occasional)

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

Overpower circuit malfunction caution

Overpower limiting not activating when input power exceeds capability

Ranked causes

1. Overvoltage detection circuit failure at 75V threshold (unknown)

First check

Monitor IPROG voltage when input reaches 75V

Test point: IPROG
Expected: transitions to more negative voltage (Low state)

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

Overpower circuit troubleshooting

Verify overpower protection circuit operation which limits load power sinking to normal (300-396 W) or extended (400-530 W) range based on heat sink temperature

Ranked causes

1. Extended power capability signal malfunction or missing external power (unknown)

First check

Monitor output voltage at overpower comparator circuit test point

Test point: Comparator output on Figure 3-10
Expected: Voltage oscillates between -14V and 0V when circuit is active, -14 to 0 V
Tools: Oscilloscope

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

Primary microprocessor read/write test failure (Error -4)

GPIB talker/listener chip communication failure detected during selftest; primary interface malfunction

Ranked causes

1. GPIB talker/listener chip U202 address or data line failure (common)

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

Primary trigger circuit test failure (Error -5, -6, -7)

Internal trigger, AC line trigger, or timer circuit trigger test failed during selftest; trigger logic malfunction

Ranked causes

1. Primary trigger circuit malfunction (occasional)

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

Risk of electrostatic discharge damage caution

Potential ESD damage to components during service procedures when protective covers are removed and power is applied

Ranked causes

1. Inadequate ESD protection measures during service (common)

First check

Verify workstation meets ESD requirements

Test point: Work surface and grounding system
Expected: Distributed resistance 10^6–10^12 Ω/sq; wrist strap 1 MΩ resistor to ground

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

Secondary microprocessor U301 internal RAM failure (Error -101)

Secondary microprocessor internal RAM selftest failure; secondary processor memory defect

Ranked causes

1. U301 internal RAM defect (rare)

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

Secondary microprocessor U301 internal timer failure (Error -103)

Secondary microprocessor internal timer selftest failure; secondary processor timer circuit defect

Ranked causes

1. U301 internal timer defect (rare)

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

SLEW readback signal absent or incorrect

Readback DAC/amplifier U322/U328 not converting SDB0-7 data to reference signal for microprocessor SLEW verification during selftest

Ranked causes

1. Readback DAC/amplifier U322/U328 failure (unknown)

First check

Measure readback signal at comparator U327 output

Test point: U327 output
Expected: Signal tracking main SLEW signal during operation

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

Transient DAC circuit zero or full scale out of tolerance (Error -107, -108)

Transient DAC U321/U325 zero point or full scale calibration exceeds tolerance limits during selftest

Ranked causes

1. Transient DAC circuit calibration error or component failure (occasional)

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

Transient mode trigger pulses not generated

Running the trigger test program does not produce 1.5µs TRIG pulses at expected test points

Ranked causes

1. Trigger circuit failure (unknown)

First check

Execute trigger test program (lines 10-70)

Test point: U311-12, U314-1
Expected: 1.5µs TRIG pulses generated continuously
Tools: BASIC program, oscilloscope

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

Error codes

Code	Meaning	Trigger	Severity
`-101`	Secondary microprocessor U301 internal RAM failure	RAM memory malfunction detected during secondary selftest part 1	error
`-102`	Power board disconnected, thermistor RT2 missing/open, or U301 internal ROM failure	Power supply verification or ROM selftest failure during secondary selftest part 1	error
`-103`	Secondary microprocessor U301 internal timer failure	Timer circuit malfunction detected during secondary selftest part 1	error
`-104`	EEPROM U342 checksum error	EEPROM checksum verification failed during secondary selftest part 2	warning
`-105`	Main DAC U320/U326 zero point above high tolerance level	DAC calibration selftest failure during secondary selftest part 2	error
`105-108`	Selftest failure error code	Error detected during power-on self-test sequence	error
`-106`	Main DAC U320/U326 zero point below low tolerance level	DAC calibration selftest failure during secondary selftest part 2	error
`-107`	Transient DAC U321/U325 zero point above high tolerance level	Transient DAC calibration selftest failure during secondary selftest part 2	error
`-108`	Transient DAC U321/U325 zero point below low tolerance level	Transient DAC calibration selftest failure during secondary selftest part 2	error
`-240`	Hardware error (secondary component failure)	EEPROM, MAIN DAC, or TRANSIENT DAC failure during secondary selftest part 2	error
`-330`	Self-test fail (primary or secondary selftest failure)	Primary or secondary selftest failure during power-on sequence	error
`-4`	Primary microprocessor read/write test to GPIB talker/listener chip failed	GPIB talker/listener chip U202 address or data line communication failure	error
`-5`	Primary microprocessor internal trigger circuit test failed	Trigger signal generation or detection failure during selftest	error
`-6`	Primary microprocessor AC line trigger circuit test failed	AC line trigger detection failure during selftest	error
`-7`	Primary microprocessor timer circuit trigger test failed	Timer-based trigger generation failure during selftest	error
`Error 105-108`	Slew circuit malfunction detected during self-test	Self-test at turn-on detects error 105-108	error
`Fan inoperative or stuck at max speed`	Fan #1 or Fan #2 does not operate or fails to respond to speed control	User reports no fan operation or continuous maximum fan speed; Power-On diagnostics may flag fan failure	warning
`Fan speed does not change`	Fan runs but speed command does not change fan RPM	User inputs speed command via front panel keypad; fan does not respond to speed changes	warning
`Frequency Selection (FSEL) Table mismatch`	Programmed frequency does not match U311-5 output as per FSEL table	Transient mode enabled with specific FSEL pin states	error
`UNKNOWN`	EEPROM not initialized or configuration data missing	EEPROM uninitialized or corrupted configuration on power-on	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.