Electrosurgical units

Codman CMC-III: troubleshooting and error codes

The ServiceForge knowledge base holds 12 documented symptoms for the Codman CMC-III, with 18 ranked causes, 18 diagnostic checks with test points and expected values, and 0 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Low power output

Generator produces less cutting or coagulation power than expected

Ranked causes

1. Low line voltage (common)
2. Incorrect test load (common)
3. Internal calibration change (rare)

First check

Measure supply line voltage

Test point: Power supply input
Expected: 120V, 220V or 240V ±10%
Tools: DMM

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

Unit does not operate high voltage

Power-on indicator light is off or non-functional

Ranked causes

1. Blown fuse (common)
2. Loose wire at power cord plug (common)
3. No power at wall outlet (occasional)

First check

Verify fuse status

Test point: Main power fuse and internal fuses F400/F402
Expected: Fuses intact and rated correctly for supply voltage

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

Calibration: Output power high voltage

Adjust target DAC calibration values for any of 40 power output settings to match desired output power into 50 or 400 ohm loads

Ranked causes

1. Factory DAC calibration values require adjustment (common)
2. EEPROM error or blank memory at first power-up (occasional)

First check

Enter calibration mode and select power setting

Test point: P203 pin 4
Expected: Unit announces 'calibrate output power'; Malis Unit setting and DAC value display on numeric LED

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

Erratic power output

Power output fluctuates or is inconsistent during operation

Ranked causes

1. Loose or dirty connections between forceps cord and jacks (common)
2. Intermittent break in forceps cord (common)

First check

Inspect bipolar cord plugs and jacks

Test point: Forceps cord connectors and generator output jacks
Expected: No visible oxidation, corrosion or looseness

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

Excessive leakage current high voltage

Unit shows excessive leakage current to ground or chassis

Ranked causes

1. Shorted output transformer (rare)

First check

Measure leakage current to ground

Test point: Generator chassis to ground
Expected: Within safe limits per IEC or applicable standard
Tools: Leakage current meter

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

Excessive power output patient safety

Generator produces more power than set or expected

Ranked causes

1. Internal calibration change (rare)

First check

Measure output power at known setting

Test point: Generator output with standard test load
Expected: Power output matches front panel setting within tolerance
Tools: Power meter or test load with measurement

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

No power output

Generator produces no cutting or coagulation power

Ranked causes

1. Broken wire in forceps cord (common)

First check

Test forceps cord continuity

Test point: Forceps cord pins and connectors
Expected: Continuity present on both conductors
Tools: DMM ohms function

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

Voice indicator announces Error

Voice alert announces error condition

Ranked causes

1. Two front panel setting controls pressed simultaneously (occasional)

First check

Verify single control operation

Test point: Front panel controls
Expected: Only one control pressed at a time

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

Voice indicator announces Footpedal error

Voice alert announces footpedal error

Ranked causes

1. Two footpedals pressed simultaneously (occasional)

First check

Verify single footpedal operation

Test point: Pneumatic and electric footpedals
Expected: Only one pedal activated at a time

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

Voice indicator announces Internal fuse high voltage

Voice alert announces internal fuse blown; power setting display flashes 00

Ranked causes

1. Blown internal fuse (common)

First check

Identify internal fuse status and type

Test point: Fuses F400 and F402 on power supply board
Expected: Fuses intact and rated for current supply voltage (110/120V, 220V, or 240V)

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

Voice indicator announces Internal power error high voltage

Voice alert announces internal power error condition

Ranked causes

1. Operating malfunction (unknown)

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

Voice indicator announces Memory error

Voice alert announces memory error during operation

Ranked causes

1. Operating malfunction (unknown)

1 corrective action and part numbers 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.