Welch Allyn 5102, 5125, 5127 Service Manual
Welch Allyn Non-Masted Scales
Service Manual
Model 5102 Physician’s Stand-On Scale
Model 5125 Portable Stand-On Scale
Model 5127 Bariatric Portable Stand-On Scale
© 2016 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.
Software in this product is Copyright 2016 Welch Allyn or its vendors. All rights are reserved. The
software is protected by United States of America copyright laws and international treaty provisions
applicable worldwide. Under such laws, the licensee is entitled to use the copy of the software
incorporated with this instrument as intended in the operation of the product in which it is embedded.
The software may not be copied, decompiled, reverse-engineered, disassembled, or otherwise reduced
to human-perceivable form. This is not a sale of the software or any copy of the software; all right, title,
and ownership of the software remain with Welch Allyn or its vendors.
For information about any Welch Allyn product, contact your local Welch Allyn representative:
http://www.welchallyn.com/en/other/contact-us.html
DIR 80021779 Ver. A
Revision date: 2017-03
Welch Allyn, Inc.
4341 State Street Road
Skaneateles Falls, NY 13153 USA
www.welchallyn.com
Customer Support
Placing orders, checking on pricing, billing, or repairs
scale-tronix@welchallyn.com
1.800.535.6663, Option 2, 1, 5
9am - 5pm EST
Mon - Fri
CONTENTS
Custom setup ................................................................................................................................................ 4
Enter custom setup mode ......................................................................................................................... 4
Set the options .......................................................................................................................................... 4
Enter Advanced Service Mode .................................................................................................................. 7
Menu List for Advanced Service Mode ..................................................................................................... 7
Support Services ........................................................................................................................................... 8
Warranty ................................................................................................................................................... 8
Repairs ...................................................................................................................................................... 8
Returning products ................................................................................................................................... 9
Warranty service ....................................................................................................................................... 9
Non-warranty service .............................................................................................................................. 10
Maintenance of Scales ................................................................................................................................ 10
Battery replacement ............................................................................................................................... 10
Calibration of Scale ................................................................................................................................. 10
Calibration Procedure ............................................................................................................................. 11
Troubleshooting of Scale ............................................................................................................................ 12
Symptom and Solutions .......................................................................................................................... 14
Disassembly Guide ...................................................................................................................................... 17
Required Tools: ....................................................................................................................................... 17
Specified Torque Values .......................................................................................................................... 17
5125 & 5127 Disassembly ....................................................................................................................... 18
5102 Disassembly.................................................................................................................................... 27
Repair Parts List .......................................................................................................................................... 34
5125 & 5127 Repair Parts List ................................................................................................................. 34
5102 Repair Parts List ............................................................................................................................. 35
Schematics .................................................................................................................................................. 36
5125/5127 Schematics ............................................................................................................................ 36
5102 Schematics ..................................................................................................................................... 41
4
Custom setup
You can customize the scale to best suit your needs. Configurations that can be selected include the automatic
shut-off time, weighing units (if available), weight resolution, and more.
Enter custom setup mode
1. Make sure the scale is powered down.
2. Press and hold ST while pressing ON.
3. Once the scale powers up, press and release ST five times. The scale displays SEt-UP and produces a series
of four long beeps.
4. The "RE CALL" pushbutton is used to select the particular option value.
5. Once this value is selected the scale can be advanced to the next option by again pressing the “ST”
pushbutton or it can be shut-off by pressing and holding the "ON" pushbutton.
Set the options
Enter the custom setup as described.
Press ST to scroll through the custom setup options.
The options displayed with each press are as follows:
Press the setup mode select button to turn these options On or OFF.
Note Options indicated with an asterisk (*) require an additional press of ST to change the value.
Option displayed Feature
SOFt This option displays the software version of your scale.
dAtE This option displays the release date of the software. The format is MM/DD/YY.
SCALE This option displays the model number of the scale.
AutOFF* This displays the number of seconds before the scale turns off. The Cont value prevents the
scale from turning off automatically.
AC con* This option causes the scale to remain on when plugged in to AC power.
rES This option allows you to change the resolution of weight. Pressing ST switches between the
following options:
0.1 pounds / 0.05 kilograms
0.1 pounds / 0.1 kilograms
0.2 pounds / 0.1 kilograms
0.5 pounds / 0.2 kilograms
1 pound / 0.5 kilograms
5
UnitS* This option allows you to change the displayed weight unit.
Note: Do not change the scale units if you have purchased the kilogram-only option.
KILOS* This option allows the weight to display in kilograms.
POUNDS* This option allows the weight to display in pounds.
bEEPEr* This option determines the audible signal that occurs when a front panel button is pressed.
rECALL* This option allows you to turn ON or OFF the RECALL button functionality.
rS-232 Detailed instructions for this feature are available from Welch Allyn. Go to
http://www.welchallyn.com/en/other/contact-us.html to find your local representative.
OutPut* This option displays the current data port output option. Detailed instructions for this feature are
available from Welch Allyn. Go to http://www.welchallyn.com/en/other/contact-us.html to find
your local representative.
Set the value to OFF to disable the optional internal printer or the RS-232 port.
PrtUnt* This option determines whether pounds or kilograms are displayed on a printout.
If the pounds and kilograms indicators are illuminated on the control panel, the printed output is
determined by whichever unit is selected on the control panel.
If the kilogram indicator is illuminated, it will only print in kilograms, regardless of the unit selected on the
control panel.
If the pounds indicator is illuminated, it will only print in pounds, regardless of the unit selected on the
control panel.
PrtOPT* Press RECALL to choose between the following options:
PnlPrt: The current weight is printed when PRINT is pressed on the control panel.
AutPrt: The current weight is automatically printed when a weight reading occurs.
bAud* This option allows you to set the baud rate. Values are 1200, 2400, 4800, 9600, and
19200.
pArity* This option allows you to change the parity between the following options:
Off: No parity, 8 data bits
Odd: Odd parity, 7 data bits
EuEn: Even parity, 7 data bits
StPbit* This option allows you to change the stop bits between the following options:
1 bit: One stop at the end of a word
2 bits: Two stops at the end of a word
6
rts.cts* This option allows you to turn On or Off the handshaking hardware for serial transmissions.
Prtbtn* This option allows you to turn On or Off the front panel PRINT button.
rtEPrt* This option allows you to turn On or Off the enabling of printing from a remote location by
connecting the receive line to the ground.
PC brd This option displays the model number of the printed circuit board. A second press of ST
displays the revision of the printed circuit board.
SEt-UP This option is displayed when you have cycled through all the options. Press and hold ON to
power down the scale.
7
Enter Advanced Service Mode
1. To enter the "service" mode start with the scale turned off.
2. Note the small "ST" logo ("ST") located directly above the "RE CALL" pushbutton, and below the “ZERO”
pushbutton on the front panel of the readout.
3. This "ST" actually contains a small hidden pushbutton.
4. Next; press and hold this "ZERO" pushbutton on the front panel while turning the power on with the "ON"
pushbutton.
5. As soon as the scale turns on release the "ZERO" pushbutton, then quickly press and release "ST" logo
pushbutton 5 times.
6. The scale will display "SERVICE" and produce a series of four long beeps.
7. "Service" mode has now been entered.
8. Pressing the "ST" pushbutton will advance the display to the next item.
9. The scale will exit the service mode automatically after 3 minutes, or can be shut-off by pressing and
holding the "ON" pushbutton for 3 or 4 seconds.
10. When the scale is turned back on, normal scale operation will resume.
Menu List for Advanced Service Mode
1. “A/D”, and next window on display will show the raw A/D reading. As you press on the Platform the A/D
reading will change. The weight change reading should be positive proportionally with the applied weight
in pounds.
2. “Test”, and the next window will start displaying the display test, Number will show across from 0 to 9
and repeat w/ DP, from right side to left side.
3. “Pr-OnS” = Power on start-up, next display will show the number of times the “ON” pushbutton has been
depressed.
4. “Pr-rcl” = Powered by Recall, next display will show the number of times the “RECALL” pushbutton has
powered-up the scale (from an off state).
5. “COUntS” = Weighing Counts, next display will show the number of times a weight reading has been
achieved.
6. “rEcntS” = Reweigh counts, next display will show the number of times “REWEIGH” pushbutton has been
depressed.
7. “rECLLS” = recalls, next display will show the number of times the “RECALL” pushbutton has been
depressed.
8. “OFFS” = Turned Off, next display will show the number of times the scale has been turned off by holding
the “ON” pushbutton down.
9. “PrintS” = Prints, next display will show the number of times the “PRINT” pushbutton has been depressed.
10. “SEtUPS” = set-up mode, next display will show the number of times the unit has entered into the set-up
mode.
11. “SEruES” = service mode, next display will show the number of times the unit has entered into the service
mode.
12. “CALS” = Cal mode, next display will show the number of times the unit has entered into the Cal mode.
8
Support Services
If you have a problem with the device that you cannot resolve, call the Welch Allyn Technical Support Center
nearest you for assistance. A representative will assist you in troubleshooting the problem and will make every
effort to solve the problem over the phone, potentially avoiding an unnecessary return.
Technical support is available 9am-5pm EST.
Welch Allyn offers the following technical support services:
• Telephone support
• Replacement service parts
• Product service
For information on any of these services, go to https://www.welchallyn.com/en/service-support.html
Warranty
Welch Allyn will warranty the weight scale to be free of defects in material and workmanship and to perform in
accordance with manufacturer specifications for the period of one year from the date of retail purchase.
The warranty period shall start on the date of purchase. The date of purchase is: 1) the invoiced ship date if the
device was purchased directly from Welch Allyn, 2) the date specified during product registration, 3) the date of
purchase of the product from a Welch Allyn authorized distributor as documented from a receipt from said
distributor.
This warranty does NOT cover damages caused by misuse or abuse, including but not limited to:
• Failure caused by unauthorized repairs or modifications
• Damage caused by shock or dropping during transportation
• Damage caused by improper use of the power supply
• Failure caused by improper operation not consistent with the instructions stated in
the Directions for use
Should this device require maintenance (or replacement at our option) under warranty, contact your local Welch
Allyn representative: http://www.welchallyn.com/en/other/contact-us.html
Repairs
A Welch Allyn Service Center or Authorized Service Provider must perform all repairs on products under warranty
unless performed by a properly certified technician.
CAUTION Unauthorized repairs will void the product warranty.
Qualified service personnel or a Welch Allyn Service Center should repair products out of warranty.
If you are advised to return a product to Welch Allyn for repair or routine maintenance, schedule the repair with
the service center nearest you.
9
Returning products
When returning a product to Welch Allyn for service, ensure that you have the following information:
Product name, model number, and serial number. This information may be found on the product and
serial number labels.
A complete return shipping address.
A contact name and phone number.
Any special shipping instructions.
A purchase-order number or credit-card number if the product is not covered by a warranty.
A full description of the problem or service request.
1. Obtain an RMA number. Contact Welch Allyn and request.
Note Welch Allyn does not accept returned products without an RMA.
2. Ship the device to Welch Allyn, observing these packing guidelines:
Remove from the device the battery, all hoses, connectors, cables, sensors, power cords, and other ancillary
products and equipment, except those items that might be associated with the problem.
Dispose of damaged or leaking batteries in an environmentally safe manner consistent with local regulations.
Note: To ensure safe receipt of your device by the service center and to expedite processing and return of the
device to you, thoroughly clean all residues from the device before you ship it to Welch Allyn. For cleaning
requirements, see the Cleaning instruction in the Directions for Use.
Welch Allyn thoroughly cleans all returned devices on receipt, but any device that cannot be adequately cleaned
cannot be repaired.
3. Write the Welch Allyn RMA number with the Welch Allyn address on the outside of the shipping carton.
Warranty service
All repairs on products under warranty must be performed or approved by Welch Allyn.
Refer all warranty service to Welch Allyn Product Service or another authorized Welch Allyn Service Center.
Obtain a Return Material Authorization (RMA) number for all returns to Welch Allyn Product Service.
CAUTION Unauthorized repairs will void the product warranty.
10
Non-warranty service
Welch Allyn Product Service Centers and Authorized Service Providers support non-warranty repairs. Contact any
Welch Allyn regional service center for pricing and service options.
Welch Allyn offers modular repair parts for sale to support non-warranty service. This service must be performed
only by qualified end-user biomedical/clinical engineers.
Maintenance of Scales
Routinely perform the following preventive maintenance to keep your scale in working order.
1. Check the calibration annually or as required.
2. Inspect the scale for cracks or loose mounting hardware. Replace or repair as necessary.
3. Visually inspect the scale enclosure for damage or loose or missing hardware. Replace or repair as
necessary.
4. If equipped, inspect the AC line cord for abrasions or other signs of wear if equipped.
5. Do not expose the scale to excessive water or moisture.
6. Do not store the scale where heavy objects can be placed on it.
7. Replace the batteries annually or as required.
8. Do not service or perform maintenance while the scale is in use with a patient.
Battery replacement
CAUTION Use only size C disposable alkaline batteries. The use of any other battery will void the warranty.
1. Using a screwdriver, remove the two battery access door screws located on the right of the display (5102 is
below display) and remove the door.
2. Install new batteries in the battery holder. Make sure to follow the polarity instructions.
3. Re-attach the access door.
Calibration of Scale
Your scale has been carefully calibrated at the factory. This calibration involves matching and tuning of the load cells
and readout electronics. The scale calibration should be checked annually. Only use calibrated, certified scale test
weights for this purpose. Traction or physical therapy weights are NOT acceptable since their actual weight can
often be in error as much as +/-10%. Calibration weights may be purchased from WELCH ALLYN or a local scale
dealer. An alternative to calibration weights is the weight comparison method. This requires a known accurate,
calibrated scale. A fixed weight is “weighed” on the calibrated scale then the same weight is placed on the scale for
comparison.
11
TEST CALIBRATION WEIGHTS ARE AVAILABLE FROM WELCH ALLYN.
THREE (3) 25 KILOGRAM TEST WEIGHTS ARE RECOMMENDED.
ORDER PART NO. 20021W. (25 KG TEST WEIGHTS)
Large changes in calibration often indicate a damaged load cell or faulty readout component. It is generally
recommended that if calibration is necessary for your scale it should be returned to the factory. Calibration should
not be attempted by those not having the proper tools or knowledge of electronic systems and their attendant shock
hazards.
Calibration Procedure
Enter the “calibration mode” by following exactly the procedure outlined below:
1. Verify serial number labels on Readout Assembly, & Base Assembly match.
2. Be sure scale is off.
3. Press and hold in the “RE WEIGH” pushbutton.
4. While pressing the “RE WEIGH” pushbutton, press and release the “ON” pushbutton.
5. NOTE: The “ST” pushbutton is a special hidden programming and test pushbutton located under the WELCH
ALLYN logo (“ST”) on the left side of the front panel between the “ZERO” and “RE CALL” pushbuttons. After
the scale displays the test pattern of “888888” release the “RE WEIGH” button and press the “ST”
pushbutton five (5) times. This will cause the readout to enter the calibration mode. The display will
indicate “CAL”.
6. Press the “ST” pushbutton once more; the display will indicate “A/D ”. This indicates the start of the “raw”
analog-to-digital converter data being inputted to the microprocessor.
7. Press the “ST” pushbutton one more time. The number displayed is now the raw analog to digital data.
8. The automatic turn-off timer has also been programmed for an extended “on” period to give you time to
calibrate the scale. This time period is three minutes. The scale may be turned off before this time period
by simply pressing and holding the “ON” pushbutton. Hold it in for several seconds until the power shuts
off. If additional time is needed to complete the calibration procedure, press the “ON” pushbutton briefly.
This will reset the timer for an additional three minutes.
The readout is displaying a number, which represents the ZERO offset value of the platform and load cell transducers,
in tenths of pounds (0.1 pound). Note and record this value. (Even though your scale may be “kilograms only” in
operation, pounds are used internally because of their finer resolution.) Units conversion is as follows:
1.0 kilogram = 2.2 (2.2046) pounds
5.0 kilograms = 11.0 (11.0231) pounds
10.0 kilograms = 22.0 (22.0462) pounds
25.0 kilograms = 55.1 (55.1156) pounds
50.0 kilograms = 110.2 (110.231) pounds
75.0 kilograms = 165.3 (165.347) pounds
100 kilograms = 220.4 (220.462) pounds
Add the specified test weight to the platform. Note the new number displayed. Subtract the original ZERO offset
value from this new number to obtain the scale’s displayed value of the calibration weight.
NOTE: Early versions of the software did not display the decimal point in the A/D mode, i.e.: 11.7 pounds is
displayed as “117”.
12
Example: The ZERO offset value is “11.7” (representing 11.7 pounds). Adding the specified three 25-kilogram test
weights (equivalent to 165.3 pounds) to the platform produces a reading of “177.1” The difference is 177.1-
11.7=165.4 (equivalent to 165.4 pounds). This would indicate the calibration is 0.1 pound “high”.
Using the specified three 25-kilogram test weights, a difference of 165.3 +/-0.1 pound should be obtained. If
necessary, adjust potentiometer P1 (span adj.) on the instrument board until the correct value is obtained. Remove
the test weight and recheck the ZERO offset value. Note that adjusting P1 may also alter the ZERO offset value.
Repeat the process as necessary to obtain the correct difference.
Now you may turn the scale off by pressing the “ON” pushbutton and holding it in for a few seconds. That will force
it to turn off. You may also wait for it to time out and turn off by itself.
DATA OUTPUT (RS232) DETAILS
For detailed help and information regarding the data output capabilities, contact Welch Allyn. RS232 data output
has been made a standard feature on many of our scales in 2013. Existing scales can be easily modified to provide
data output when needed. Consult Welch Allyn for details.
Troubleshooting of Scale
The internal microcomputer contained in the readout constantly monitors the scale’s operation and uses the display
to indicate error conditions when they arise. An explanation of these messages is given below:
“bAttrY”: Indicates the battery has become depleted to the point that it can no longer operate the scale.
Replace the battery to continue operation.
“O-LOAd”: Shows that the scale platform’s weighing capacity has been exceeded. Refer to the inside front
cover specifications for maximum capacity.
“CAbLE”: Displays that the transducer signal is well in excess of its maximum value. This is usually caused
by the transducer cable being disconnected. Check the cable connection between the display and the
weighing platform.
“OFF SCALE, PLEASE –“ : Remove the weight from the weighing platform and allow the scale to obtain
“ZERO”.
“E-FAIL”, “r-FAIL”: Shows that a memory failure has occurred in the internal microcomputer’s memory.
Requires service of the scale.
The following simplified trouble shooting procedures are recommended for identifying defective system
components. Certain corrective measures are provided. More complicated servicing should only be performed by
the factory or authorized service facilities. Most problems can be solved over the telephone. Problems requiring
factory service are usually handled quickly and the scale is on its way back. Call first to discuss the problem.
WEIGHT READING NOT ACCURATE
This can commonly be caused by a mechanical obstruction of the weighing platform. Check that the platform is not
touching some foreign object so that it is restricted in its’ downward movement. Also check that the connecting
cable is firmly plugged into the instrument circuit board (marked “J4 LOAD CELL”).
WEIGHT READING TAKES EXCESSIVE TIME TO DISPLAY
If the platform is in motion, the scale will wait for it to settle before displaying the weight. This can be caused by
excessive patient motion.
13
Also check that the connecting cable is firmly plugged into the readout cabinet. Examine the weighing platform that
it is not rubbing against a foreign object.
SCALE DISPLAYS “CAbLE” OR “O-LOAd”
This indicates the scale’s internal microcomputer has received a signal in excess of its expected value. “O-LOAd”
indicates the weight signal is larger than the maximum value assigned to that particular model (see specifications on
inside front cover). If the weight value is within the specified range, this indicates a damaged transducer or defective
instrument board.
The “CAbLE” display indicates a signal outside the range of the internal A/D converter has been applied. This is most
likely caused by a damaged or disconnected transducer cable. On those scales with a mast, check the connection to
the weighing platform at its base. Also check the internal connection of the four wire cable to the “J1 LOAD CELL”
connector.
READING DOES NOT CHANGE WHEN WEIGHT APPLIED
Check that the weight platform is plugged into the readout. The platform cable, connector or load cell transducer
may be defective. The load cell transducer’s resistance can be checked with an ohmmeter after unplugging from
the readout. The proper resistance values are listed below:
WIRE COLORS (PIN NO.) RESISTANCE
GRN(1)/BLK(2)/WHT(3)/RED(4) >10MΩ
GRN(1) TO BLK(2) 350-450Ω
WHT(3) TO RED(4) 325-375Ω
Consult Welch Allyn if readings differ from those shown.
NOTE: Ohmmeters will not indicate a change in resistance of the load cell transducer when weights are applied to
scale. This is due to the extremely small change in resistance of the strain gauges employed (<1 ohm) and the fact
that the bridge configuration presents a constant value of resistance when measured from its terminals.
NON-FUNCTIONING KEYS(S)
Check the front panel keyboard for visible signs of damage (punctures, dents, etc.). Check that keyboard tail with
connector is properly inserted into the display board.
If a particular function does not work (example” no kilogram units) check if that particular function is turned off in
the “SET-UP” mode.
ERROR MESSAGE DISPLAYED: “E-FAIL” OR “r-FAIL”
This indicates a failure of the internal microcomputer’s memory during the start-up self-test. “E-FAIL” indicates a
failure of the microcomputer’s eprom memory during the checksum test. “r-FAIL” shows a failure of the random
access memory. Both conditions require replacement of the microcomputer.
14
Symptom and Solutions
Symptom
Possible
Cause
Corrective Action
Scale does not
turn on
Dead Batteries or
no rear Adapter
Replace Batteries (Alkaline “C” Cells)
Faceplate
Remove Front Panel. Check to make sure the Black and Red
cable connector is in place. Replace the switch assembly or
the Battery Holder Assembly.
Cracked Battery
Holder
Display
Board/Main
board
Replace the board
Inaccurate
Weights, Scale not
weighing
correctly, scale
broken, drifting
Load
Cell/Calibration
(OHM out Load Cells) See Calibration procedure this Service
Manual
Bad A/D Chip
Removing the top plate, the load cells will be visible
1. Enter into “Cal Mode” from the front panel
2. Press and hold the Reweigh button
3. Turn the Scale on
4. Release the Reweigh button immediately
5. Immediately go to the ST logo and press 5 X
6. Display should say “CAL”
7. Press ST Logo two more times to display A/D
Readings
Note: A/D reading without a load. Look for a low stable
weight reading less than 10 lbs and that is not drifting or
unstable.
Unplug each load cell and connect one at a time to see if
your display becomes unstable. This will tell you which load
cell needs to be replaced
Cold Solder on
the Calibration
Plug
Check Gain Resistor R24 on the Cal Chip, Replace Cal chip if
necessary.
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