ECG analyzers · MAC family

GE Healthcare MAC 5500: troubleshooting and error codes

The ServiceForge knowledge base holds 55 documented symptoms for the GE Healthcare MAC 5500, with 107 ranked causes, 102 diagnostic checks with test points and expected values, and 8 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Visual inspection items found caution

Inspection identifies physical damage, loose connections, or component issues

Ranked causes

1. Frayed or damaged I/O connectors and cables (occasional)
2. Fuse issues (occasional)
3. Interface cable damage or loose connections (common)
4. Circuit board contamination or damage (occasional)
5. Ground wire or wiring issues (occasional)
6. Loose or missing mounting hardware (occasional)
7. Power source problems (occasional)

First check

Visual inspection of I/O connectors and cables

Test point: Connectors, cable ends, plugs
Expected: No fraying, damage, bent prongs, cracked housing, or loose screws

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

Unit does not start or power-up self-test fails

Equipment not functioning properly on power-up; internal self-test fails to display startup screen

Ranked causes

1. Unit not turned on (common)
2. No AC power supplied (common)
3. Battery not installed (occasional)
4. Writer door open or loose connections (occasional)
5. Equipment configuration change or operator error (occasional)
6. Hardware or software modification (rare)

First check

Verify unit power switch is on

Test point: Power switch
Expected: Power switch in ON position

3 more checks with pass and fail actions, 6 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

ECG data displays unacceptable noise levels patient safety

Acquired ECG signal contains excessive noise making diagnosis difficult

Ranked causes

1. Improper electrode placement (common)
2. Improper electrode application or contamination (common)
3. Defective or out of date electrodes (occasional)
4. Defective, broken, or disconnected leadwires (occasional)
5. Patient movement during acquisition (common)

First check

Verify proper electrode placement

Test point: electrode positions
Expected: per ECG protocol

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

Missing ACI-TIPI Report patient safety

ACI-TIPI interpretation report not displayed or generated

Ranked causes

1. ACI-TIPI is disabled (common)
2. Report selected without interpretation option (occasional)
3. Required patient information not entered (common)
4. Patient entered as pediatric with invalid age range (rare)
5. Original ECG acquired without ACI-TIPI option (rare)

First check

Verify ACI-TIPI is enabled in system settings

Test point: software settings menu
Expected: ACI-TIPI enabled

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

Poor quality ECGs patient safety

ECG acquisition produces poor signal quality, unreadable traces, or inadequate waveforms

Ranked causes

1. Environmental factors (common)
2. Inadequate patient preparation (common)
3. Hardware failures in acquisition module (occasional)
4. Leadwire or cable problems (occasional)
5. Unit malfunction (occasional)

First check

Test with simulator

Test point: Simulator input
Expected: Good ECG report from simulator signal

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

No blood pressure reading from external device

Blood pressure data is not received from connected external device

Ranked causes

1. Incorrect setup configuration (unknown)
2. Suntech protocol misconfiguration (unknown)
3. Defective or disconnected cables (common)
4. TTL trigger malfunction (occasional)

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

No BP from External Device patient safety

Blood pressure not received or displayed from external BP monitoring device

Ranked causes

1. Device setup not configured correctly (common)
2. Protocol mismatch (Suntech device) (occasional)
3. Serial or TTL cable disconnected or defective (common)
4. TTL trigger signal not active (occasional)

First check

Verify external device setup configuration

Test point: system setup menu
Expected: external BP device enabled and configured

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

Treadmill or Ergometer Does Not Move caution

Treadmill or ergometer equipment will not start or respond to control commands

Ranked causes

1. Protocol not configured (common)
2. Control cables disconnected or defective (common)
3. Input/Output settings not configured (occasional)
4. Emergency Stop switch engaged (occasional)

First check

Verify equipment protocol configured

Test point: protocol settings menu
Expected: treadmill or ergometer protocol selected

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

Treadmill/Ergometer does not move patient safety

Exercise equipment fails to start or operate during stress testing

Ranked causes

1. Incorrect protocol setting (common)
2. Defective or disconnected cables (common)
3. Incorrect input/output settings (common)
4. Emergency Stop switch activated (occasional)

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

Self-test failure on power-up caution

Internal self-test fails on startup, system does not display normal startup screen

Ranked causes

1. Hardware or software modified since last use (occasional)
2. Environmental or usage changes (occasional)
3. Operator error (common)

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

Thermal writer produces poor print quality

Printed output shows distortion, skewing, crushing, curved lines, misalignment, or uneven darkness

Ranked causes

1. Print head speed or paper tracking problem (common)
2. Flat spot on print roller (occasional)
3. Missing print head dot (occasional)

First check

Verify first character printed is not distorted

Test point: Printed output start
Expected: First character clear and properly formed without distortion

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

Unit does not power on

System does not start, no display or startup screen appears

Ranked causes

1. Unit turned off (common)
2. Battery not installed (occasional)
3. No AC power or faulty AC connection (common)

First check

Verify unit power switch is on

Test point: Power switch
Expected: Switch in ON position

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

Acquisition module not responding

Acquisition module does not communicate with system; power test fails; noise levels abnormal

Ranked causes

1. Acquisition module power supply failure (common)
2. Acquisition module communication circuit defect (occasional)

First check

Run acquisition module power test

Test point: Acquisition module power supply
Expected: Module powered and responding to test commands
Tools: Shorting bar (required)

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

Acquisition module test fails

Acquisition module does not respond or communication test fails during diagnostic

Ranked causes

1. Acquisition module not powered or communication disabled (common)
2. Acquisition module hardware failure (occasional)

First check

Install shorting bar and run acquisition module test

Test point: Acquisition module
Expected: Module powered and communicating; button presses detected

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

Battery voltage abnormal

Battery voltage outside acceptable range; does not charge or discharge properly; depletes rapidly

Ranked causes

1. Battery requires replacement (common)
2. Main CPU board failure (occasional)

First check

Run Battery Status test

Test point: System battery
Expected: Battery voltage between 15 and 24 volts at 80% or higher charge; current between -0.7 and 0.7 amps V, 15–24 V at ≥80% charge
Tools: System Diagnostics menu

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

Ethernet module test fails

Ethernet module IP address and subnet mask display N/A or test is unsuccessful

Ranked causes

1. Ethernet module hardware failure (occasional)
2. Network configuration issue (common)

First check

Verify Ethernet cable connection

Test point: Ethernet port
Expected: Cable firmly connected

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

External modem not responding

External modem ID and firmware revision display N/A during External Modem Test

Ranked causes

1. Modem not connected to COM 2 or modem power off (common)
2. Serial communication failure between unit and modem (occasional)

First check

Verify modem connection to COM 2 and power

Test point: COM 2 port
Expected: Modem powered on and connected

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

Internal memory test detects bad blocks

Internal Memory Tests display indicates presence of bad blocks in storage

Ranked causes

1. Internal storage memory corruption or hardware defect (occasional)
2. Internal storage memory circuit failure (rare)

First check

Run Internal Memory Tests and note bad block count

Test point: Internal memory storage
Expected: Zero bad blocks; free memory displayed

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

Internal modem not responding

Internal modem ID and firmware revision display N/A during Internal Modem Test

Ranked causes

1. Internal modem hardware failure or firmware issue (occasional)
2. Main CPU modem control circuit failure (rare)

First check

Run Internal Modem Test and check result

Test point: Modem response
Expected: ID number and firmware rev display (not N/A)

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

Modem communication unsuccessful

Modem does not respond to test commands; ID number and firmware revision display as N/A

Ranked causes

1. External modem not connected or defective (common)
2. Internal modem circuit failure (occasional)

First check

Run External Modem Test

Test point: COM 2 port (modem connection)
Expected: Modem ID number, firmware revision, and parameter settings display correctly

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

SD card read/write test failed

SD card cannot be read or written; test returns failure result; memory card appears defective

Ranked causes

1. Defective SD card (common)
2. CPU board SD card interface failure (occasional)

First check

Insert non-write-protected SD card

Test point: SD card slot
Expected: Card inserted and detected by system

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

SD card test fails

SD Card Test returns Failed status during read/write test

Ranked causes

1. SD card defective or incompatible (common)
2. SD card controller on main CPU board failure (occasional)

First check

Insert non-write-protected SD card and run SD Card Test

Test point: SD card slot
Expected: Test displays 'Passed'

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

Serial communications port test fails

COM loopback test returns Failed after installing loopback jumpers

Ranked causes

1. Serial port hardware defect or loopback jumper not installed (common)
2. Main CPU board serial port circuit failure (occasional)

First check

Install loopback jumpers and run COM loopback test

Test point: Selected COM port (COM1, COM2, COM3, or COM4)
Expected: Test displays 'Passed'

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

Ambient temperature inside unit excessive caution

Internal ambient temperature more than 10°C above room temperature

Ranked causes

1. Cooling fan malfunction or airflow obstruction (common)

First check

Compare internal and external temperatures

Test point: Ambient temperature display
Expected: Internal temperature ≤ 10°C above room temperature

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

Analog input voltage measurement failed

Measured voltage from external DC power supply does not display correctly; analog input circuit not responding

Ranked causes

1. Main CPU board analog input circuit defect (unknown)

First check

Run Analog Input Test with external DC power supply

Test point: DC input pins (ANA/TTL connector)
Expected: Applied voltage correctly displayed on test screen
Tools: DC power supply

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

Analog input voltage not reading correctly high voltage

Voltage applied to analog input does not display correctly during Analog Input Test

Ranked causes

1. Analog input circuit fault on main CPU board (common)

First check

Connect DC power supply to DC input pins and read displayed value

Test point: ANA/TTL connector analog input
Expected: Displayed voltage matches applied voltage
Tools: DC power supply, oscilloscope

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

Analog output voltage incorrect

DC output, ECG output, or trigger output voltage does not match expected value when measured

Ranked causes

1. Main CPU board DAC (analog output) circuit defect (unknown)

First check

Measure +12V output

Test point: Oscilloscope connected to appropriate pins per Analog Output Test
Expected: +12 V DC
Tools: Oscilloscope

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

Battery capacity below minimum

Discharge capacity measured less than 2000 mAH during battery status check

Ranked causes

1. Battery aging or internal chemical degradation (common)

First check

Check battery discharge capacity

Test point: Battery status display
Expected: Discharge capacity ≥ 2000 mAH

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

Battery current excessive with no AC power

Battery current less than -0.7 amps (more negative) when AC power not applied

Ranked causes

1. Main CPU board drawing excessive standby current (occasional)

First check

Monitor battery current with AC power off

Test point: Battery status display
Expected: Battery current ≥ -0.7 amps A

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

Battery voltage too low

Battery voltage below 15 volts when percent charge is 80% or more

Ranked causes

1. Battery internal resistance increase or cell failure (common)

First check

Monitor battery voltage during charge cycle

Test point: Battery status display
Expected: 15 to 24 volts (when charge ≥ 80%) V, 15-24 V

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

Communication port test failed

Serial communication port does not transmit or receive data correctly; loopback test fails

Ranked causes

1. Serial port hardware defect or CPU board failure (unknown)

First check

Install loopback jumper and run COM port test

Test point: COM port (1, 2, 3, or 4)
Expected: Test result Passed; all ASCII characters transmitted and received correctly
Tools: Loopback jumpers

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

DC output loopback test fails high voltage

Loopback test detects incorrect values on analog inputs when DC outputs are sent

Ranked causes

1. Analog output or input circuit fault on main CPU board (common)

First check

Connect DC outputs to analog inputs and run loopback test

Test point: ANA/TTL connector DC outputs looped to analog inputs
Expected: Test displays 'Passed'

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

DC output to analog input loopback test failed

Test cannot confirm correct values read from analog inputs when DC outputs are driven; loopback path broken

Ranked causes

1. Main CPU board analog output or input circuit defect (unknown)

First check

Run DCOut Loopback Test

Test point: DC output to analog input path (ANA/TTL connector pins)
Expected: Pass result; all values transmitted and received correctly
Tools: Internal loopback connection per test instructions

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

Display brightness or contrast out of range

Screen brightness or contrast appears abnormal; grey scale test pattern shows unusual intensity

Ranked causes

1. Display settings out of specification (unknown)

First check

Examine brightness and contrast of test patterns

Test point: Display screen
Expected: Brightness and contrast within normal range; no unusual intensity variation

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

Display pixels not functioning

Missing or non-working pixels visible on screen during pixel verification test

Ranked causes

1. Display hardware defect (unknown)

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

Display screen pixels not working

Missing or non-functional pixels visible on display during operation

Ranked causes

1. Defective display panel (unknown)

First check

Verify all screen pixels illuminate

Test point: Display screen
Expected: All pixels visible; no missing or dark spots

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

ECG output loopback test fails high voltage

Loopback test detects incorrect ECG output or QRS trigger output values

Ranked causes

1. ECG output circuit or QRS trigger circuit fault on main CPU board (common)

First check

Connect ECG output and QRS trigger to analog inputs and run loopback test

Test point: ANA/TTL connector ECG and trigger outputs looped to analog inputs
Expected: Test displays 'Passed'

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

ECG output to analog input loopback test failed

Test cannot confirm ECG output and QRS trigger output transmit correctly to analog inputs; loopback path broken

Ranked causes

1. Main CPU board ECG output or analog input circuit defect (unknown)

First check

Run ECGOut/QRSTrigger Loopback Test

Test point: ECG output and QRS trigger output to analog input path (ANA/TTL connector pins)
Expected: Pass result; ECG signal and trigger waveforms transmitted and received correctly
Tools: Internal loopback connection per test instructions

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

Equipment hardware or environmental issues caution

Visible signs of hardware defects, disconnection, or contamination

Ranked causes

1. Disconnected cables, debris, missing hardware, loose components (common)

First check

Visual inspection of I/O connectors and cables

Test point: Connectors, cable plugs
Expected: No fraying, bent prongs, cracked housing, or loose screws

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

Equipment malfunction after configuration change

Unit fails after change in use, location, environment, or modification of hardware/software

Ranked causes

1. Use, location, or environment change affecting operation (occasional)

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

Ethernet module test failed

Ethernet module does not respond; IP address, subnet mask, and MAC address display as N/A

Ranked causes

1. Ethernet module circuit failure or disconnection (unknown)

First check

Run Ethernet Module Test

Test point: Ethernet module interface
Expected: Device IP address, subnet mask, and MAC address display correctly (not N/A)

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

Internal memory read/write test failed

Internal storage memory does not read or write correctly; bad blocks detected; memory test returns error

Ranked causes

1. Internal memory hardware failure (common)

First check

Run Internal Memory Tests

Test point: System internal storage memory
Expected: No bad blocks; free memory available; test passes

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

Keyboard key input not recognized

Pressing keys does not produce expected on-screen response; key presses not highlighted or displayed

Ranked causes

1. Non-functional keyboard key or keyboard circuit (unknown)

First check

Verify each key produces response on screen

Test point: Keyboard keys and arrow pad
Expected: Key highlighted and displayed on screen; scan code shown at top; normal dim background may remain

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

Keyboard key not responding or not displayed

Key press not highlighted on screen or numeric scan code not displayed at top of screen

Ranked causes

1. Keyboard hardware defect or connection issue (unknown)

First check

Press individual keys during keyboard test

Test point: Keyboard keys
Expected: Key highlighted on screen and scan code displayed at top

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

Software installation fails on -008 main board

Cannot install software versions 9C or 10A on MAC 5500 with 801212-008 main board; boot code prevents installation

Ranked causes

1. Incompatible software version for -008 CPU (common)

First check

Verify main board model number

Test point: main board
Expected: 801212-008 or other model

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

Speaker produces no sound

No audible tone output when speaker test is run; speaker appears non-functional

Ranked causes

1. Main CPU board failure (speaker integrated) (common)

First check

Run Speaker Test

Test point: System speaker output
Expected: Audible tone (loud or soft) produced
Tools: Ears to detect sound

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

Speaker produces no tone

No audible output when speaker test is run with Loud or Soft selection

Ranked causes

1. Main CPU board failure (speaker is part of CPU board) (common)

First check

Run speaker test and select Loud or Soft

Test point: Speaker output
Expected: Audible tone at selected volume level

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

Thermal writer has flat spot on roller caution

Isolated light spots visible in roller test pattern indicating roller defect

Ranked causes

1. Roller mechanical wear or flatness defect (occasional)

First check

Run roller test and inspect output pattern

Test point: Roller test output
Expected: Diagonal light and dark wavy bands without isolated light spots

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

Thermal writer has missing print head dot caution

White line visible across full length of page in roller test output

Ranked causes

1. Print head mechanical damage or nozzle failure (occasional)

First check

Run roller test and inspect for white lines

Test point: Roller test pattern
Expected: No white lines across page length

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

Thermal writer paper travel is not smooth caution

Paper motion during writer test shows hesitation, resistance, or irregular movement

Ranked causes

1. Paper path obstruction or roller friction (common)

First check

Observe paper movement during test

Test point: Paper feed path
Expected: Paper moves smoothly without hesitation or jerking

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

Thermal writer prints curved or wavy lines caution

Large triangles and diagonal lines are curved or wavering instead of straight and uniform

Ranked causes

1. Writer motor speed control or mechanical wear (common)

First check

Measure printed line straightness

Test point: Printed triangles and diagonal lines
Expected: Lines straight and uniform without curves or wavering

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

Thermal writer prints distorted first character caution

First character printed is distorted or unclear at start of writer test

Ranked causes

1. Writer motor start-up speed issue (common)

First check

Examine first character in writer test output

Test point: First printed character
Expected: First character not distorted

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

Thermal writer prints skewed or crushed paper edges caution

Output shows uneven paper edge tracking or paper compression during writing

Ranked causes

1. Paper tracking or tension mechanism misalignment (common)

First check

Inspect paper edges in test output

Test point: Paper edge alignment
Expected: Both edges straight and even, no crushing or skewing

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

Thermal writer test output misaligned with tear bar caution

Perforations do not align with tear bar on writer door after paper cueing

Ranked causes

1. Paper cueing mechanism misalignment (occasional)

First check

Inspect perforation alignment after paper cueing

Test point: Tear bar alignment
Expected: Perforations aligned with tear bar

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

Thermal writer test pattern length incorrect caution

Printout length does not meet specification of 250 mm ± 5 mm for test patterns

Ranked causes

1. Motor speed control error at tested speed (common)

First check

Run 50 mm/s test pattern and measure length

Test point: Test pattern output length
Expected: 250 mm ± 5 mm (use grids on page), ±5 mm

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

Error codes

Code	Meaning	Trigger	Severity
`Battery icon appears on screen`	No battery installed in the system	System powered on without battery present	warning
`Battery icon flashes intermittently`	Battery charge is low	System operating on battery power with insufficient remaining charge	warning
`Cannot use the system because Device Password does not work`	Device password authentication failure	Incorrect device password entered or system password changed	error
`MODEM ERROR. The remote device is not responding. Would you`	Modem connection failure; remote device not responding	System attempts to transmit data to remote device but connection cannot be established or maintained	error
`System does not power up when operating from battery power`	System fails to start on battery power	Power button pressed while on battery with insufficient charge	error
`System shuts down when operating from battery power`	System unexpectedly powers off during battery operation	Battery becomes depleted during operation or automatic shutdown feature activates	warning
`Writer door icon appears on screen`	The writer door is open	Writer door detected as open during operation or startup	warning
`X Lead disconnected message`	Electrode connection lost	One or more electrodes become physically disconnected from patient or connector	error

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.