Lincoln Electric 9904 User Manual
9 9 0 4
9 9 0 4
The Service Department is receiving an increasing number of warranties claimed on PC boards that when analyzed,
"Check OK". To avoid delays in processing your warranty, please make sure that your warranty is completely filled out
with a detailed description of the end-user's problem along with your diagnosis and repair procedures. Anytime a
diagnosis points to changing a PC board, follow these procedures:
WARNING! Electric shock can kill. Please follow the troubleshooting procedures listed in the Lincoln Service
Manual (SVM) for the machine that you are working on.
WARNING! Turn the input power off at the fuse box before working on the machine. Do not touch electrically hot
NEW PC BOARD TROUBLESHOOTING & REPLACEMENT PROCEDURE
1. Follow the warnings above and determine to the best of your technical ability what PC board is most likely causing
the failure symptom. Troubleshooting steps are outlined in each machine's SVM. Please note the procedure number
and page on the warranty report.
2. Check for loose connections at the PC board to assure that the board is properly connected. Check each individual
lead that is going into the connector. Pull, wiggle and tug on every lead to insure that each connector is "latched" into
Check ground path connections, including those used as PC board mounting points, for clean secure contact.
3. Unplug each connector and look into the end of the connector and check to see if each metal pin is straight and not
bent or pushed to the side of the cavity.
4. Check all of the receiving connectors on the PC board for any bent or missing pins. Replug all of the connectors
making sure that they are "snapped" into place.
5. Close up all necessary covers and restart the machine. If the same symptom exists, shut off the machine and
change the suspect PC board using standard practices to avoid electrical damage and electrical shock. Read the
WARNING inside the static resistant bag and follow handling procedures.
6. It is desirable to have a known good test PC board available for troubleshooting. These are available through the
Service Department, see Service Notice #9401. If the installation of the troubleshooting board corrects the symptom a
new replacement PC board can be installed.
7. Test the machine to determine if the failure symptom has been corrected by the replacement PC board. Allow the
machine enough time to heat up to operating temperature for this test.
Note: It is normal for some power resistors to smoke and turn black because of the heating of sealant coating used
to protect the PC board from moisture.
To: All Lincoln Sales Offices and Service Facilities
Subject: PC BOARD TROUBLESHOOTING PROCEDURE
Page 1 of 2
Description of Notice
Return to Main Menu