Electrosurgical units

ConMed 7550: troubleshooting and error codes

The ServiceForge knowledge base holds 87 documented symptoms for the ConMed 7550, with 149 ranked causes, 67 diagnostic checks with test points and expected values, and 56 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Err 306 displayed

PW_MEA out of calibration - Power measurement is out of tolerance.

Ranked causes

1. U7 on Power Control Failed on A4 (occasional)
2. Ramp transistors Q1 or Q2 failed (occasional)
3. U14B on A4 Failed (occasional)
4. U21 - Port A wrong data on A4 and A5 (occasional)
5. D/A Failed - PCON on A5 (occasional)

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

Err 302 displayed

IMEA Error - Output current measurement is out of tolerance or power regulation has failed.

Ranked causes

1. Output Current Error too high on A4 (common)
2. Too much power into a heavy load (occasional)
3. Power Regulation Loop failed on A4 (occasional)
4. D/A Failed - PCON on A5 (occasional)

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

Err 316 displayed high voltage

HV Idle Test - High voltage monitor or supply circuits not properly in idle state.

Ranked causes

1. HVMON circuit failed on A1 (occasional)
2. 10V circuit on A7 Failed (occasional)
3. J3 disconnected on A7 (occasional)
4. J1 disconnect on A1 (occasional)

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

ABC mode will not initiate or activate

ABC (automatic blend control) mode fails to start or respond to activation request

Ranked causes

1. Over-voltage circuit active or over-voltage threshold exceeded (common)
2. U7 failed or pulse width/duty cycle error (occasional)
3. U4 control signal failure (rare)

First check

Recalibrate ABC over-voltage

Test point: ABC mode control circuit
Expected: Over-voltage threshold reset; ABC mode initiates normally

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

Dual Pad monitor set will not lock patient safety

Dual Pad electrode monitoring mode fails to lock or maintain connection with monitor set

Ranked causes

1. PP receptacle resistance too high (>10 ohms) (common)
2. Monitor set switch on overlay failed (occasional)
3. A.R.M. (Automatic Return Monitor) calibration error (rare)

First check

Measure PP receptacle resistance

Test point: PP receptacle connector
Expected: >12 ohms, > 12 ohms

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

Err 1 displayed

Front panel switch stuck or defective during power-up; Front Panel overlay failed or U5 microcontroller defective.

Ranked causes

1. User pressing switch during power-up (common)
2. Front Panel overlay failed (occasional)
3. U5 (A5) microcontroller failed (occasional)

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

Err 111 displayed

FMON (Flow Monitor) out of tolerance - Flow control circuit or measurement is out of calibration.

Ranked causes

1. FMON out of calibration on A1 (common)
2. Flow Control Valve Driver shorted on A1 (occasional)
3. Argon tubes to X1 reversed on A1 (occasional)

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

Err 112 displayed

Flow Error - Flow measurement or control is out of calibration or circuit has failed.

Ranked causes

1. FMON out of Calibration on A1 (common)
2. Handpiece occluded (common)
3. Flow control circuit has failed (occasional)

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

Err 2 displayed

Hand or foot activation switch stuck or failed accessory (handcontrol or footcontrol) preventing normal operation.

Ranked causes

1. User pressing switch during power-up (common)
2. Failed Handcontrol or Footcontrol (common)
3. Failed component on A5 or A11 (occasional)

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

Err 233 displayed

Data transfer to Monitor failed - Communication between Controller and Monitor microcontrollers has failed.

Ranked causes

1. Mailbox Failed on A5 (occasional)
2. Data Bus bad on A5 (occasional)
3. Address Bus bad on A5 (occasional)

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

Err 301 displayed

Flow Error - Flow measurement is too high or low, or D/A converter failure affecting gas flow control.

Ranked causes

1. Flow too high or low (common)
2. Flow Rate too high for accessory (common)
3. D/A Failed - VGAS on A5 (occasional)

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

Err 307 displayed

FB Amp Drive Error - Feedback amplifier drive circuit failed on Power Control PCB.

Ranked causes

1. U7 on A4 Failed (occasional)
2. U14A on A4 Failed (occasional)
3. U21 - Port A wrong data on A4 and A5 (occasional)

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

Err 308 displayed high voltage

HVDC too high - High voltage control circuit or monitoring circuit has failed.

Ranked causes

1. HV Control Loop failed on A1 (occasional)
2. HV Monitor Failed on A1 (occasional)
3. D/A Failed - VCON on A5 (occasional)

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

Err 315 displayed

Flow Idle Error - Flow control circuit not properly inhibited during idle state.

Ranked causes

1. Flow Control Loop Failed on A1 (occasional)
2. Driver Q2 Failed on A1 (occasional)
3. U15B Failed on A1 (occasional)

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

Err 323 displayed

FB Amp Drive Error - Feedback amplifier drive circuit failure on Power Control PCB.

Ranked causes

1. U7 on A4 Failed (occasional)
2. U14A on A4 Failed (occasional)
3. U21 - Port A wrong data on A4 and A5 (occasional)

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

Flow rate too high caution

Argon gas flow rate exceeds expected rate or control setting on display

Ranked causes

1. Driver Q2 shorted on A1 board (occasional)
2. Argon pressure transducer hoses reversed (occasional)
3. Control loop failure on A1 board (rare)

First check

Measure Q2 emitter voltage during flow operation

Test point: Q2 emitter pin (A1 board)
Expected: Voltage increases progressively with increasing flow rate

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

Handsense control not responding or intermittent patient safety

Handcontrol switch activation does not register or registers intermittently; control signals not reaching RF circuits

Ranked causes

1. Continuity transformer T3 primary drive signal loss (occasional)
2. Opto-isolator LED failure in handswitch detection circuit (occasional)
3. Handswitch mechanical contact failure or corrosion (common)

First check

Measure NE555 timer U3 drive signal on T3 primary

Test point: U3 output pin; T3 primary winding
Expected: 100 KHz square wave, 20% duty cycle
Tools: Oscilloscope

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

Low or zero RF output power high voltage

RF Output Assembly fails to produce expected power across Cut, Blend, Pinpoint, Bipolar or Spray modes

Ranked causes

1. Faulty relay in RF output path (common)
2. Relay driver failure on Display Assembly (occasional)
3. Open circuit or disconnection in output relay switching path (occasional)

First check

Verify relay driver is providing drive signal

Test point: Relay driver output on Display Assembly
Expected: Drive signal present for activated mode

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

No Activation or Tone

Unit will not activate or produce tone when handcontrol or footcontrol is pressed.

Ranked causes

1. Activation agreement error between Controller and Monitor (common)
2. Handsense Circuit failed (common)
3. RF Jack worn out (occasional)

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

Pneumatic flow control or solenoid valve not responding caution

Argon gas flow does not modulate or solenoid valve fails to open/close; pneumatic manifold not functioning

Ranked causes

1. Solenoid valve coil open or shorted (occasional)
2. Solenoid valve driver transistor failure or open base/collector (occasional)
3. Proportioning valve controller current not increasing with flow setting (occasional)

First check

Measure solenoid valve coil resistance

Test point: Digital (solenoid) valve coil terminals
Expected: 72 ohms
Tools: DMM ohmmeter

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

Regulator thermal shutdown activated on 15 V or 5 V supply caution

System loses 15 V or 5 V power due to regulator overheating; load current exceeds safe operating range

Ranked causes

1. Shorted component on downstream assembly drawing excessive current (common)
2. Regulator Q1, Q2, or Q5 internal short or degradation (occasional)
3. 5 V switcher LC filter capacitor failure or degradation (occasional)

First check

Measure regulator output current with all loads connected

Test point: Regulator output line or dedicated current sense resistor
Expected: 15 V regulator: <500 mA typical; 5 V switcher: <2 A typical (per schematic)
Tools: DMM or power supply with current monitoring

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

RF leakage detected or excessive RF leakage during operation caution

System detects unbalanced RF current returning via alternate paths; leakage current exceeds balanced condition threshold

Ranked causes

1. Unbalanced condition in Balun transformer T4 (common)
2. Damaged or faulty Balun sensing winding (occasional)
3. Patient return isolation relay failure (K8, K9, K11) (occasional)

First check

Measure balun sense winding voltage

Test point: Balun sense winding
Expected: 0 V under balanced condition; voltage increases proportional to leakage current

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

Err 120 displayed

Controller and Monitor microcontrollers disagree on power level, indicating data communication or encoder logic failure.

Ranked causes

1. Bad data transfer between Controller and Monitor on A5 (occasional)
2. PIA with encoder logic failed on A5 (occasional)

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

Err 20 displayed caution

Illegal Default Switch Setting - unit is in TEST MODE instead of RUN MODE, or default switch position 1 or 6 is ON.

Ranked causes

1. Default switch position 1 or 6 is ON (common)
2. System in TEST MODE (common)

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

Err 203 displayed

Mailbox error - Bad data transfer or mailbox communication failure between Controller and Monitor.

Ranked causes

1. Bad data transfer on A5 (occasional)
2. Mailbox failed on A5 (occasional)

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

Err 210 displayed

Bad Calibration Data - Calibration data stored in EEPROM is invalid or corrupted.

Ranked causes

1. Calibration Data bad on A5 (common)
2. EEPROM failed on A5 (occasional)

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

Err 252 displayed

EEPROM error - CRC validation of EEPROM data failed or data is corrupted.

Ranked causes

1. CRC error on A5 (common)
2. Bad data stored in EEPROM on A5 (occasional)

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

Err 304 displayed

Output Power - Power control circuit or D/A converter failure preventing proper power regulation.

Ranked causes

1. Power Control Circuit Failed on A4 (occasional)
2. D/A Failed - PCON on A5 (occasional)

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

Err 313 displayed

IMEA idle - Current measurement idle error indicating improper idle state voltage.

Ranked causes

1. U14D Failed on A4 (occasional)
2. U12 or U8 Failed on A5 (occasional)

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

Err 331 displayed high voltage

HV out of range - High voltage DC supply exceeds tolerance during power-on self-test.

Ranked causes

1. HVDC too high during POST (occasional)
2. Triac Failure on A7 (occasional)

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

Err 332 displayed high voltage

HV not inhibited by monitor - High voltage control failed to inhibit during power-on self-test.

Ranked causes

1. HVINH failed to inhibit HVDC during POST (occasional)
2. Fuse on HV Power Supply open or missing (occasional)

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

Half Power in Cut, Blend, Pinpoint, Bipolar

Unit outputs half power in Cut, Blend, Pinpoint, or Bipolar modes instead of full power.

Ranked causes

1. A phase of the Full Bridge Amp failed (common)
2. Open power FET or no RF Drive to power FET (common)

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

High voltage supply exceeds 205 VDC high voltage

DC voltage supply reads above 205 VDC in one or more RF modes

Ranked causes

1. Triac (MT1 or MT2) failed in one mode (common)
2. Control loop failure (occasional)

First check

Measure DC voltage in Cut mode

Test point: HVDC supply line
Expected: ≤205 VDC

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

Keyboard switches not responding

Front panel switches do not change indicators or modes when pressed; no response to user input

Ranked causes

1. Front panel overlay switch failure (common)
2. Switch scanner circuit failure (occasional)

First check

Disconnect J1 harness and apply jumper test

Test point: J1 connector pins 1-4 shorted to pins 5-8
Expected: Front panel indicators change state in response to jumper

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

No power in Spray or ABC

Unit outputs no power in Spray or ABC modes despite activation.

Ranked causes

1. Open power FET on SE Amp (common)
2. No RF Drive on SE Amp (common)

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

No RF output in any mode high voltage

System does not produce RF power output from any jack in Cut, Spray, or other modes

Ranked causes

1. Open relay in output circuit (common)
2. Relay driver circuit failed (common)

First check

Test RF output from all jacks in Cut mode

Test point: Cut mode RF output jacks
Expected: RF signal present at output jacks

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

Breaker trips when system is activated high voltage

Main power breaker trips immediately upon system activation or power-on

Ranked causes

1. Shorted power FET on RF amplifier (common)

First check

Identify affected amplifier

Test point: System activation mode
Expected: FB amp (Cut/Pinpoint) or SE amp (Spray/ABC) identified

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

Calibration: A.R.M. Max Voltage loading high voltage

Load A.R.M. maximum voltage value into EEPROM for Cut window second number

Ranked causes

1. A.R.M. Max Voltage value needs loading into EEPROM (common)

First check

Verify S1 Position 1 switch setting and remove Patient Return Adaptor

Test point: Switch 1 (S1) Position 1 and Patient Return Connector
Expected: S1 Position 1 ON (up); Patient Return Adaptor removed

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

Calibration: ABC mode 150W high voltage

ABC mode 150W output power needs calibration adjustment

Ranked causes

1. ABC 150W output power out of calibration (common)

First check

Measure ABC RF output power at 150W setting

Test point: Patient Return and ABC Output Connector
Expected: 150W ±2W, ±2W
Tools: ESU analyzer, 500 ohm load, ABC adaptor

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

Calibration: ABC mode 15W high voltage

ABC mode 15W output power needs calibration adjustment

Ranked causes

1. ABC 15W output power out of calibration (common)

First check

Measure ABC RF output power at 15W setting

Test point: Patient Return and ABC Output Connector
Expected: 15W ±2W, ±2W
Tools: ESU analyzer, 500 ohm load, ABC adaptor

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

Calibration: ABC mode Active pulse width high voltage

Verify ABC Active mode pulse width modulation for power control

Ranked causes

1. ABC Active mode power output out of specification (unknown)

First check

Measure ABC Active mode minimum pulse width

Test point: SE signal in Active mode
Expected: 200nS minimum µs
Tools: Oscilloscope

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

Calibration: ABC mode Target/Booster pulse characteristics high voltage

Verify ABC Target and Booster mode pulse sequences and timing without load

Ranked causes

1. ABC Target/Booster mode RF leakage elevated (unknown)

First check

Measure ABC Target mode pulse width

Test point: SE signal with no handpiece load
Expected: 400nS µs
Tools: Oscilloscope

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

Calibration: ABC Over Voltage protection high voltage

ABC over-voltage limit setting to prevent output exceeding 3500Vpk

Ranked causes

1. ABC over-voltage clipping limit out of calibration (common)

First check

Connect oscilloscope probe differentially to ABC and Patient Return outputs

Test point: ABC and Patient Return outputs
Expected: Oscilloscope configured for differential measurement with both channels at maximum amplitude

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

Calibration: ABC PW_MEA EEPROM loading at 11W high voltage

Load ABC pulse width measurement values at 11W into EEPROM for Coag window display

Ranked causes

1. ABC 11W PW_MEA value needs loading into EEPROM (common)

First check

Verify S1 Position 1 switch setting

Test point: Back side of display panel, Switch 1 (S1), Position 1
Expected: ON (up)

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

Calibration: ABC PW_MEA EEPROM loading at 149W high voltage

Load ABC pulse width measurement values at 149W into EEPROM for Cut window display

Ranked causes

1. ABC 149W PW_MEA value needs loading into EEPROM (common)

First check

Set and activate ABC at 149W

Test point: ABC power control
Expected: 149W

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

Calibration: Bipolar RF output high voltage

Bipolar mode output power needs adjustment to meet 50W specification

Ranked causes

1. Bipolar RF output power out of calibration (common)

First check

Measure Bipolar RF output power

Test point: Bipolar RF Output Jacks
Expected: 50W ±2W, ±2W
Tools: ESU analyzer, 100-125 ohm load

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

Calibration: dP (delta pressure) signal in standby

Verify differential pressure output is zero when unit is in standby mode

Ranked causes

1. dP signal not zero in standby (unknown)

First check

Measure delta pressure output TP3 in standby mode

Test point: TP3
Expected: 0V

1 more check with pass and fail actions are in ServiceForge. Connect ServiceForge to your AI

Calibration: FMEA signal voltage

Verify argon back pressure monitoring signal FMEA is within operating range

Ranked causes

1. FMEA signal out of specification (unknown)

First check

Measure FMEA voltage signal

Test point: display assembly input
Expected: 2V to 3.5V, +/-0.75 V

Calibration: FMON signal voltage at 4 lpm

Verify proportioning valve current monitor signal FMON is calibrated correctly

Ranked causes

1. FMON signal out of specification (unknown)

First check

Measure FMON voltage at 4 lpm flow setting

Test point: display assembly input
Expected: 2V
Tools: DMM

Calibration: Full Bridge Amplifier drive waveforms high voltage

Verify H-bridge power switching operation and output waveform characteristics

Ranked causes

1. Output waveform not meeting frequency or timing specifications (unknown)

First check

Measure drive frequency on 01 and 02 signals

Test point: U1 output to Q2 and U2 output
Expected: 461 KHz kHz
Tools: Oscilloscope

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

Calibration: Single-Ended Amplifier Spray mode high voltage

Verify Spray mode drive cycle timing and power control voltage

Ranked causes

1. Spray mode output power out of specification (unknown)

First check

Measure Spray mode drive pulse repetition rate

Test point: SE signal from Power Control Assembly
Expected: 35µS repetition rate µs
Tools: Oscilloscope

1 more check with pass and fail actions are in ServiceForge. Connect ServiceForge to your AI

Calibration: Spray Coag PW_MEA EEPROM loading high voltage

Load Spray Coag pulse width measurement values into EEPROM for RF Drive monitoring

Ranked causes

1. Spray Coag PW_MEA value needs loading into EEPROM (common)

First check

Verify S1 Position 1 switch setting

Test point: Back side of display panel, Switch 1 (S1), Position 1
Expected: ON (up)

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

Err 200 displayed

Interrupt error - Unused interrupt was triggered unexpectedly during operation.

Ranked causes

1. Unused Interrupt tripped (rare)

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

Err 201 displayed

Mailbox error - Monitor did not read message from Controller, indicating communication failure.

Ranked causes

1. Monitor did not read message on A5 (occasional)

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

Err 202 displayed

Mailbox error - Monitor did not respond to Controller message, indicating communication failure.

Ranked causes

1. Monitor did not respond on A5 (occasional)

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

Err 216 displayed

RAM Failure - External RAM memory on Display PCB has failed.

Ranked causes

1. External RAM U2 failed on A5 (rare)

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

Err 218 displayed

Bad EPROM CRC - EPROM checksum validation failed indicating memory corruption or defective chip.

Ranked causes

1. EPROM U1 failed on A5 (rare)

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

Err 219 displayed

CPU RAM Failed - Microcontroller internal RAM has failed preventing normal operation.

Ranked causes

1. Micro Internal RAM failed in U15 on A5 (rare)

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

Err 220 displayed

CPU Failed - Main microprocessor on Display PCB has failed.

Ranked causes

1. Microprocessor U15 failed on A5 (rare)

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

Err 251 displayed

EEPROM error - EEPROM read/write failure on Display PCB.

Ranked causes

1. Bad EEPROM or U27 on A5 (occasional)

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

More symptoms

Err 26 displayed
Err 303 displayed
Err 305 displayed
Err 309 displayed
Err 310 displayed
Err 311 displayed
Err 312 displayed
Err 314 displayed
Err 318 displayed
Err 319 displayed
Err 320 displayed
Err 321 displayed
Err 324 displayed
Err 325 displayed
Err 326 displayed
Err 327 displayed
Err 328 displayed
Err 329 displayed
Err 330 displayed
Err 41 displayed
Err 42 displayed
Err 43 displayed
Err 44 displayed
Err 55 displayed
Fuses or R19 resistor blowing repeatedly
Intermittent activation with handcontrol
Spray mode will not deliver power

27 more symptoms with ranked causes and checks are in ServiceForge. Connect ServiceForge to your AI

Error codes

Code	Meaning	Trigger	Severity
`301`	Mode or control error with status flags	During ABC mode activation with low gas supply and other mode/status conditions active	warning
`386`	Tone monitor signal error or failure	T_MON signal from A5 board fails or goes invalid	error
`Err 1`	Stuck Front Panel Switch or Front Panel overlay failed or U5 microcontroller defective	Front panel switch stuck during power-up or overlay failure	error
`Err 111`	FMON out of tolerance - Flow Monitor out of calibration	Flow measurement outside acceptable range during operation	warning
`Err 112`	Flow Error - Flow measurement out of calibration or control failed	Flow rate abnormal or flow control circuit failure detected	warning
`Err 120`	Controller and Monitor disagree on power level	Data mismatch between Controller and Monitor microcontrollers on power setting	error
`Err 2`	Stuck Hand or Foot Activation Request	Activation switch stuck during power-up or defective handcontrol/footcontrol	error
`Err 20`	Illegal Default Switch Setting - position 1 or 6 is ON	Unit powered up with incorrect default switch configuration	critical
`Err 200`	Interrupt - Unused Interrupt tripped	Unexpected interrupt signal detected during operation	error
`Err 201`	Mailbox - Monitor did not read message	Communication timeout between Controller and Monitor	warning
`Err 202`	Mailbox - Monitor did not respond	Communication timeout from Monitor to Controller	warning
`Err 203`	Mailbox error - Bad data transfer or mailbox failed	Mailbox communication protocol error detected	warning
`Err 210`	Bad Cal Data - Calibration data invalid or corrupted	Stored calibration data fails validation during startup	warning
`Err 216`	RAM Failure - External RAM has failed	Memory test failure detected during power-on or operation	critical
`Err 218`	Bad EPROM CRC - EPROM checksum validation failed	EPROM data integrity check failed during startup	critical
`Err 219`	CPU RAM Failed - Microcontroller internal RAM failed	CPU RAM integrity check failed during startup or operation	critical
`Err 220`	CPU Failed - Microprocessor failed	CPU test or operation failure detected	critical
`Err 233`	Data transfer to Monitor failed	Communication error between Controller and Monitor microcontrollers	error
`Err 251`	EEPROM error - Read/Write failure	EEPROM read or write operation failed	error
`Err 252`	EEPROM error - CRC validation failed	EEPROM data integrity check failed	warning
`Err 26`	Stuck encoder bits or Logic device failed	Encoder input stuck or logic device failure detected	error
`Err 301`	Flow Error - Flow measurement out of tolerance	Flow measurement too high or low during operation	warning
`Err 302`	IMEA Error - Output Current measurement error too high	Output current exceeds tolerance during operation	warning
`Err 303`	Activation Error - Controller and Monitor disagree on activation	Mismatch in activation request or mode between microcontrollers	error
`Err 304`	Output Power - Power control circuit failed	Power control regulation failure detected	error
`Err 305`	Activation Error - Monitor activation request failed	Monitor cannot process activation request from Controller	error
`Err 306`	PW_MEA out of calibration - Power measurement out of tolerance	Power measurement fails calibration tolerance check	warning
`Err 307`	FB Amp Drive Error - Feedback amplifier drive circuit failed	Feedback amplifier drive signal abnormal or absent	error
`Err 308`	HVDC too high - High voltage DC supply out of tolerance (high)	High voltage DC supply exceeds 200V limit	critical
`Err 309`	FBMON idle limit too high - Feedback monitor idle voltage excessive	Feedback monitor idle voltage exceeds 155mV threshold	warning
`Err 310`	10V Reference - 10V reference voltage out of tolerance	10V reference supply fails tolerance check on Display PCB	error
`Err 311`	15V supply - 15V power supply out of tolerance	15V power supply fails tolerance check	error
`Err 312`	PW_MEA idle - Power measurement idle error	Power measurement fails idle state validation	warning
`Err 313`	IMEA idle - Current measurement idle error too high	Current measurement fails idle state validation	warning
`Err 314`	Stuck Activation Request - Activation signal remains asserted	Activation request signal stuck in active state	error
`Err 315`	Flow Idle Error - Flow control not properly inhibited at idle	Flow measurement exceeds 150mV during idle state	warning
`Err 316`	HV Idle Test - High voltage not properly inhibited at idle	High voltage monitor or supply circuit failure at idle state	warning
`Err 318`	Micro CRC - Monitor microcontroller checksum validation failed	Monitor microcontroller firmware integrity check failed	critical
`Err 319`	Micro RAM - Monitor microcontroller internal RAM failed	Monitor microcontroller RAM integrity check failed	critical
`Err 320`	Micro Failed - Monitor microcontroller failed	Monitor microcontroller failure detected	critical
`Err 321`	Test Switch - Unit in TEST MODE instead of RUN MODE	Default switch configuration indicates TEST MODE during operation	warning
`Err 323`	FB Amp Drive Error - Feedback amplifier drive circuit failed	Feedback amplifier drive signal abnormal or absent	error
`Err 324`	FB Amp not inhibited - Feedback amplifier not disabled during POST	RF feedback amplifier failed to inhibit during power-on self-test	error
`Err 325`	Gas Flow not inhibited - Solenoid valve failed to turn off during POST	Gas solenoid valve remains active during power-on self-test	error
`Err 326`	Gas Flow not inhibited by Controller - Flow detected when solenoid off	Monitor detected FMON > 150mV when solenoid should be off during POST	error
`Err 327`	SE Amp not in range - Single-ended amp output power out of tolerance at POST	Single-ended RF amplifier power measurement fails tolerance during power-on self-test	error
`Err 328`	SE Amp not inhibited by Monitor - RF drive failed to terminate during POST	Single-ended RF amplifier failed to shut down during power-on self-test	error
`Err 329`	ABC Over Voltage Test failed - ABC protection circuit failed during POST	ABC over-voltage protection circuit test failure during power-on self-test	error
`Err 330`	ABC Over Voltage Test failed - Protection or RF drive activation failed at POST	ABC over-voltage protection circuit test or RF drive activation failed during power-on self-test	error
`Err 331`	HV out of range - High voltage DC supply exceeds tolerance at POST	High voltage DC supply too high during power-on self-test	critical
`Err 332`	HV not inhibited by monitor - High voltage failed to inhibit during POST	High voltage DC supply failed to inhibit during power-on self-test	critical
`Err 41`	Calibration Tolerance Error - ARMCAL_10 too low	ARMCAL_10 measurement fails calibration tolerance check (too low)	warning
`Err 42`	Calibration Tolerance Error - ARMCAL_10 too high	ARMCAL_10 measurement fails calibration tolerance check (too high)	warning
`Err 43`	Calibration Tolerance Error - ARMCAL_150 too low	ARMCAL_150 measurement fails calibration tolerance check (too low)	warning
`Err 44`	Calibration Tolerance Error - armcal_150 too high	armcal_150 measurement fails calibration tolerance check (too high)	warning
`Err 55`	Watchdog Reset - Timing Error in U15	Watchdog timer detected timing error in microcontroller	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.