
Welch Allyn GS 777 Wall
Transformer
Service manual

© 2012 Welch Allyn. All rights are reserved. To support the intended use of the product described in this publication,
the purchaser of the product is permitted to copy this publication, for internal distribution only, from the media
provided by Welch Allyn. No other use, reproduction, or distribution of this publication, or any part of it, is permitted
without written permission from Welch Allyn. Welch Allyn assumes no responsibility for any injury to anyone, or for
any illegal or improper use of the product, that may result from failure to use this product in accordance with the
instructions, cautions, warnings, or statement of intended use published in this manual.
Welch Allyn is a registered trademark of Welch Allyn.
For information about any Welch Allyn product, call Welch Allyn Technical Support:
USA
+1 800 535 6663
Australia
+61 2 9638 3000
+1 315 685 4560
Canada
European Call Center
Germany
Malaysia
Singapore
United Kingdom
Material Number 718860 Ver. B
+1 800 561 8797
+353 46 90 67790
+49 695 098 5132
Japan
+81 42 703 6084
+603 7875 3341
+65 6419 8100
Spain
+34 917 499 357
+44 207 365 6780
China
France
Italy
Latin America
Netherlands
South Africa
Sweden
+86 21 6327 9631
+33 155 69 58 49
+39 026 968 2425
+1 305 669 9003
+31 202 061 360
+27 11 777 7555
+46 85 853 6551
Welch Allyn, Inc.
4341 State Street Road
Skaneateles Falls, NY 13153-0220 USA
www.welchallyn.com
Regulatory Affairs Representative
Welch Allyn Limited
Navan Business Park
Dublin Road
Navan, County Meath
Republic of Ireland

© 2012 Welch Allyn. All rights are reserved. To support the intended use of the product described in this publication,
the purchaser of the product is permitted to copy this publication, for internal distribution only, from the media
provided by Welch Allyn. No other use, reproduction, or distribution of this publication, or any part of it, is permitted
without written permission from Welch Allyn. Welch Allyn assumes no responsibility for any injury to anyone, or for
any illegal or improper use of the product, that may result from failure to use this product in accordance with the
instructions, cautions, warnings, or statement of intended use published in this manual.
Welch Allyn is a registered trademark of Welch Allyn.
For information about any Welch Allyn product, call Welch Allyn Technical Support:
USA
+1 800 535 6663
Australia
+61 2 9638 3000
+1 315 685 4560
Canada
European Call Center
Germany
Malaysia
Singapore
United Kingdom
Material Number 718860 Ver. B
+1 800 561 8797
+353 46 90 67790
+49 695 098 5132
Japan
+81 42 703 6084
+603 7875 3341
+65 6419 8100
Spain
+34 917 499 357
+44 207 365 6780
China
France
Italy
Latin America
Netherlands
South Africa
Sweden
+86 21 6327 9631
+33 155 69 58 49
+39 026 968 2425
+1 305 669 9003
+31 202 061 360
+27 11 777 7555
+46 85 853 6551
Welch Allyn, Inc.
4341 State Street Road
Skaneateles Falls, NY 13153-0220 USA
www.welchallyn.com
Regulatory Affairs Representative
Welch Allyn Limited
Navan Business Park
Dublin Road
Navan, County Meath
Republic of Ireland

Contents
Symbol descriptions ............................................................................... 1
Safety ....................................................................................................... 3
Overview .................................................................................................. 5
v
General warnings and cautions ..................................................................................................... 3
General safety considerations ........................................................................................................ 4
Electrostatic discharge (ESD) ......................................................................................................... 4
Purpose and scope ........................................................................................................................... 5
Technical support services ............................................................................................................. 5
Service options .................................................................................................................................. 5
Repairs ................................................................................................................................................ 6
Returning products ........................................................................................................................... 6
Controls, indicators, and connectors ..................................................... 9
Troubleshooting .................................................................................... 11
Symptoms and solutions ................................................................................................................ 13
Disassembly and repair ........................................................................ 15
Required tools and equipment ...................................................................................................... 15
Remove rear housing, handles, circuit board, cradle wire harnesses, and cradles ........... 15
Functional verification and calibration ................................................ 19
Functional verification tests .......................................................................................................... 19
Verify functionality .......................................................................................................................... 19
Field replaceable units .......................................................................... 21
GS 777 Wall Transformer ............................................................................................................... 21
Appendices ............................................................................................ 23
Decontamination and cleaning requirements ............................................................................ 23

vi Contents Welch Allyn GS 777 Wall Transformer

Symbol descriptions
AC input power
DC input power
1
DC output power
Separate Waste Electronic and Electrical Equipment (WEEE) from other disposables.
Prepare this product for reuse or separate collection as specified by the WEEE
Directive 2002/96/EC or local law.
The product does not contain hazardous substances above threshold values defined
in China Standard SJ/T 11363 – 2006. The product is green and environmental and can
be recycled after use.
Illuminated: Power is present. Not illuminated: No power.
Type BF applied part

2 Symbol descriptions Welch Allyn GS 777 Wall Transformer

Safety
3
All users of the device must read and understand all safety information presented in this manual
before using or repairing the device.
United States federal law restricts this device to sale, distribution, or use by or on the order of a
licensed medical practitioner.
General warnings and cautions
WARNING Read and understand the instructions before using this product.
Failure to understand the operating requirements for this product can result in injury
to you or the patient and can damage the product.
WARNING Explosion hazard. Do not operate this product in the presence of
flammable anesthetics or other flammable substances in combination with air,
oxygen-enriched environments, or nitrous oxide.
WARNING Electric shock hazard. Do not simultaneously touch the patient and
the center metal contact of the handle.
WARNING Do not modify this equipment. Any modification of this equipment can
lead to patient injury. Any modification of this equipment voids the product
warranty.
WARNING Welch Allyn is not responsible for the integrity of any mounting
installation. Welch Allyn recommends that customers contact their Biomedical
Engineering Department or maintenance service to ensure professional installation
for safety and reliability of any mounting accessory.
Caution As a precaution, avoid using this product in close proximity to other
equipment. The product complies with current required standards for
electromagnetic interference and should not present problems to other equipment
or be affected by other devices.
Caution Only authorized Welch Allyn Service Centers can perform service on this
product.
Caution To make sure that the transformer can be unplugged from the AC power
source, never block access to the wall socket.
Caution Rx only (for professional use).