ECG devices

Welch Allyn AT-10 Plus: troubleshooting and error codes

The ServiceForge knowledge base holds 42 documented symptoms for the Welch Allyn AT-10 Plus, with 61 ranked causes, 98 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

Print quality degraded or misaligned

Printout shows fading, misalignment, faulty pixels, or irregular blackness across print width

Ranked causes

1. Thermal print head contamination or wear (common)
2. Low quality or expired paper installed (common)
3. Electrical or mechanical print head misalignment (occasional)
4. Printer mechanism defective (occasional)

First check

Enter test screen and initiate continuous test print

Test point: Test screen
Expected: Continuous test print initiated

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

Mechanical condition degraded or safety labels missing caution

Cracks or chips in casing; damaged cables; loose connectors; unreadable or missing safety labels

Ranked causes

1. Physical damage from drops, impacts, or environmental exposure (occasional)
2. Cable insulation damaged by crushing, chafing, or cuts (occasional)
3. Safety label worn, faded, or detached (occasional)

First check

Inspect external casing for cracks, chips, or impact damage

Test point: Entire device exterior
Expected: No visible cracks or chips in plastic or metal casing

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

Printer paper feed misaligned caution

Paper does not stop at perforation point after manual start/stop cycle

Ranked causes

1. Non-SCHILLER paper or wrong paper type used (common)
2. Paper detection opto window contaminated (occasional)
3. Paper mark detection circuit defective (rare)

First check

Load SCHILLER paper and press Man Start

Test point: Paper transport mechanism
Expected: Paper feeds through printer

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

Software update fails or is interrupted during PC-based update caution

Unit software update via SWUP program does not complete; device may not restart automatically after download

Ranked causes

1. Unit powered off during update process (common)
2. PC COM port misconfiguration (occasional)
3. Incompatible operating system (occasional)

First check

Verify unit power status during update

Test point: Unit power indicator
Expected: Unit powered on and AC adapter connected

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

Unit will not operate caution

Device does not power on when switched with On/Off key

Ranked causes

1. Battery fully discharged (common)
2. Mains power not connected (common)
3. Damaged mains lead (occasional)

First check

Verify mains power connection

Test point: Power cable connection at rear of unit
Expected: Cable connected and Mains indicator lamp lit

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

Battery indicator lamp not lit

LED indicator (2) does not illuminate or battery symbol missing from LCD (4) when on battery power

Ranked causes

1. Battery not charged or discharged (common)
2. Battery capacity depleted (occasional)

First check

Verify device powered by mains before disconnecting

Test point: Mains indicator LED (1)
Expected: Mains indicator lit

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

ECG amplifier or patient cable defective patient safety

ECG leads show incorrect mV readings or excessive noise; missing or intermittent electrode signals

Ranked causes

1. Patient cable disconnected or loose connection (common)
2. ECG amplifier circuit defective or gain mismatch (rare)

First check

Connect patient simulator and press ECG key

Test point: ECG input connector
Expected: Electrode screen displayed; mV readings visible for all leads

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

ECG traces not displayed on screen

Patient simulator connected but ECG waveform does not appear on display

Ranked causes

1. Patient cable not properly connected (unknown)
2. Patient simulator not powered on (unknown)

First check

Verify patient cable connection between simulator and unit

Test point: SCHILLER patient cable connectors
Expected: Cable properly seated and connected

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

Electrical safety hazard during operation high voltage

Risk of electrical shock or leakage current when unit is not properly grounded or mains lead is damaged

Ranked causes

1. Missing or suspect earth connection (occasional)
2. Leakage current from connected external equipment (occasional)

First check

Verify mains lead earth connection

Test point: Mains plug and wall socket
Expected: Earth pin properly inserted and secured in grounded socket

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

External monitor not displaying or incorrect display settings

External VGA monitor shows no image or different data than LCD display after connection

Ranked causes

1. External Display config not enabled in settings (common)
2. Monitor cable not connected or VGA connector loose (occasional)

First check

Connect external VGA monitor to back panel external monitor connector

Test point: External monitor VGA connector on back panel
Expected: Monitor cable seated firmly; monitor powered on

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

Keyboard non-responsive or keys stuck caution

Function keys do not respond, no acoustic confirmation when pressed, or visible mechanical damage

Ranked causes

1. Mechanical damage or excessive wear on keyboard (occasional)
2. Key contacts dirty or non-conductive (occasional)

First check

Inspect keyboard for cracks, chips, or visible wear

Test point: All keys on keyboard
Expected: No mechanical damage visible; keys operate freely

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

No printout after automatic ECG recording

Automatic ECG recording does not produce printout after approximately 10 seconds

Ranked causes

1. Printer not operational or out of paper (unknown)
2. Auto Mode Format configuration not set (unknown)

First check

Verify ECG was recorded and result displays on screen

Test point: LCD display
Expected: Result displayed on screen

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

Printer output speed incorrect caution

Printed waveform spacing does not match expected calibration distances at specified print speeds

Ranked causes

1. Incorrect print speed setting (common)
2. Paper drive motor or speed control circuit defective (occasional)

First check

Connect calibrated simulator with HR 60/min, no arrhythmias

Test point: ECG input from patient simulator
Expected: HR displays 60 on LCD

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

Analogue ports not functioning

DC Out, DC In, QRS Out, Load Out, Load In, RPM In, Fuss In outputs not responding correctly during Ergo test

Ranked causes

1. Analogue port communication or signal integrity issue (unknown)

First check

Connect DC In/Out test cable to analogue ports

Test point: DC OUT 1, DC OUT 2, DC IN 1, DC IN 2, QRS OUT, RPM IN, LOAD OUT, LOAD IN, FUSS IN, TM UP, TM DOWN
Expected: Signals transmit and receive without errors on all tested analogue channels

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

Battery capacity insufficient

Device does not provide minimum one hour runtime on battery power after full charge

Ranked causes

1. Battery capacity degraded or defective (unknown)

First check

Fully charge battery by leaving unit connected to mains

Test point: Mains power supply
Expected: Eight hours charging time

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

Battery capacity limited

Battery LED blinking indicates low battery capacity; unit should be reconnected to mains supply for charging

Ranked causes

1. Internal battery not fully charged (common)

First check

Observe Battery LED indicator status

Test point: Battery LED on unit casing
Expected: Blinking indicates limited capacity

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

Battery replacement needed high voltage

Battery running time falls substantially under 2 hours; replacement required approximately every 4 years depending on application

Ranked causes

1. Battery aged or degraded capacity (common)

First check

Verify actual running time is substantially under 2 hours

Test point: Device operation
Expected: Less than 2 hours running time indicates replacement needed

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

Battery stored for extended period

Battery recharge requirement after storage exceeding three months

Ranked causes

1. Battery discharge during storage (common)

First check

Verify storage period

Test point: Device history
Expected: Storage duration exceeds three months

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

Calibrate battery capacity

Battery capacity appears limited or inaccurate; recalibration needed after battery replacement or during service.

Ranked causes

1. Battery installed or capacity needs recalibration (common)

First check

Unit powered only by battery until depleted

Test point: Battery voltage via hardware counter
Expected: Unit switches off when battery empty

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

Calibration: battery replacement high voltage

Battery replacement procedure with calibration and capacity verification after installation

Ranked causes

1. Battery end of life or insufficient runtime (common)

First check

Disconnect device from mains

Test point: Power inlet
Expected: Device unplugged

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

Connected equipment not compliant with IEC standards patient safety

Ancillary equipment connected to analogue or digital interfaces does not meet IEC certification requirements

Ranked causes

1. Non-IEC certified equipment connected to interfaces (occasional)

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

Damaged mains lead or earth connection suspect high voltage

Mains lead is damaged, suspected of being damaged, or earth connection is suspect

Ranked causes

1. Defective or damaged mains cable (common)

First check

Inspect mains lead for damage or degradation

Test point: Mains lead
Expected: No visible damage, cracks, or degradation

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

Device opened without disconnecting from mains high voltage

Risk of electric shock when device is opened while connected to power

Ranked causes

1. Device opened while powered (unknown)

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

ECG printout waveform does not match reference patient safety

Printed ECG shape or polarity differs from standard reference; measurement values outside tolerance

Ranked causes

1. Auto mode settings incorrect or corrupted (occasional)

First check

Connect simulator and select calibrated reference EN 60601-2-51 > CAL 20160

Test point: Simulator output configuration
Expected: Reference waveform selected

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

Faulty pixels on printout

ECG printout exhibits defective or missing pixels in the output

Ranked causes

1. Printer head defect or paper quality issue (unknown)

First check

Inspect ECG printout for faulty or missing pixels

Test point: Printed ECG paper
Expected: No faulty pixels in printed ECG

Fuse needs replacement high voltage

Device requires fuse replacement due to blown fuse or routine maintenance

Ranked causes

1. Blown fuse (unknown)

First check

Verify correct fuse type for mains voltage

Test point: Fuse assembly voltage indication window
Expected: Voltage range matches device setting: 220-240 VAC or 100-115 VAC

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

Fuse replacement with incorrect type or rating high voltage

Defective or ruptured fuse replaced with wrong type or rating

Ranked causes

1. Incorrect fuse type or rating installed (occasional)

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

Language, date, or time not set correctly

Device displays wrong language, date, or time; menu settings not saved

Ranked causes

1. User did not confirm language, date, or time selection (common)

First check

Press Menu key to open system menu

Test point: Menu button on device
Expected: System menu displayed with tabs

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

LCD screen defective or uneven contrast caution

Visible spots, black fields, or uneven contrast/brightness across display; backlight appears faulty

Ranked causes

1. LCD backlight failure or defective LCD panel (occasional)

First check

Visually inspect LCD for dark spots or black fields

Test point: Entire LCD display area
Expected: No spots or minimal defects (few faulty pixels normal); even contrast and brightness

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

LCD screen does not light

Display fails to illuminate or ECG acquisition screen not displayed after powering on

Ranked causes

1. Unit not powered on or startup delay (unknown)

First check

Press On key and observe LCD screen illumination

Test point: LCD display
Expected: LCD screen lights and ECG acquisition screen is displayed after a few moments

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

Liquid spilled on device high voltage

Liquid has been spilled over the AT-10 Plus ECG device

Ranked causes

1. Liquid contamination (occasional)

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

Mains indicator lamp not lit

LED indicator (1) does not illuminate when power cable connected to mains supply

Ranked causes

1. Power cable not connected or loose connection (common)

First check

Verify power cable connected to mains supply

Test point: Rear panel power connector
Expected: Mains indicator lamp (1) lit

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

Mains LED does not light

Green mains LED fails to illuminate when power is connected

Ranked causes

1. Mains power not connected or defective (unknown)

First check

Verify mains power connection and check green mains LED illuminates

Test point: Mains LED indicator
Expected: Green mains LED lights

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

Mains voltage needs adjustment high voltage

Device mains voltage selector requires adjustment for different supply voltage

Ranked causes

1. Mains voltage setting incorrect for local supply (unknown)

First check

Verify voltage indication after rotating inset

Test point: Voltage indication window on fuse assembly
Expected: Correct voltage range displayed: 220-240 VAC or 100-115 VAC

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

Missing pixels on LCD screen

LCD display exhibits defective or missing pixels

Ranked causes

1. Display panel defect (unknown)

First check

Inspect LCD screen for missing or defective pixels

Test point: LCD display surface
Expected: No missing pixels visible

Non-recommended accessories or parts used patient safety

Device operated with accessories or parts not recommended or supplied by Schiller AG

Ranked causes

1. Incompatible or non-approved accessories installed (occasional)

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

Patient proximity distance insufficient patient safety

Patient positioned less than 1.5 meters from device when connected to ancillary equipment without isolation

Ranked causes

1. Insufficient patient clearance from device (occasional)

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

Print quality degraded or faint output caution

Printed ECG waveforms are faint, unclear, or have poor contrast on paper

Ranked causes

1. Print head worn or thermal print mechanism degraded (occasional)

First check

Access service screen and run print quality diagnostic

Test point: Service screen menu
Expected: Print quality test executed and results displayed

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

Printer head misaligned or calibration waveforms offset caution

Calibration waveforms not vertically aligned on paper; lateral deviation exceeds tolerance

Ranked causes

1. Mechanical adjustment of print head out of alignment (occasional)

First check

Remove simulator and press Man Start

Test point: Printer manual feed
Expected: Printer operates without patient cable connected

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

RS-232 port not functioning

Red indicator square does not turn green when RS-232 test plug is inserted into Treadmill, Ergo, or RS-232 port

Ranked causes

1. RS-232 port communication failure (unknown)

First check

Insert RS-232 test plug into port

Test point: Treadmill (back panel), Ergo (back panel), or RS-232 (side panel)
Expected: Red square indicator changes to green

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

Software option installation incomplete

Software option code accepted but option may not be properly saved in the unit

Ranked causes

1. Option not saved after code entry (occasional)

First check

Verify option installation in Software screen

Test point: Software screen menu
Expected: Option displayed and saved status confirmed

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

Software option upgrade fails or freezes after multiple attempts

Unit freezes during program option installation after approximately 10 or more unsuccessful upgrade attempts; unit cannot be upgraded and must be returned to manufacturer

Ranked causes

1. Excessive failed upgrade attempts (approximately 10 or more) (common)

First check

Count unsuccessful upgrade attempts

Test point: Number displayed to right of code entry field (4)
Expected: Less than approximately 10 attempts

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.