Heal Force Prince 120 Body Fat User manual

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
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Prince 120 Body Fat
Measuring Apparatus
Service Manual
Version：2008.08.01

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
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COPYRIGHT
1. Without the written permission of our company, any content of the manual
should by no means be duplicated or disclosed to any other individual or
organization.
2. Individual or organization should in no way use the manual unless authorized
by our company.
3. Our company has the sole right to change or modify this manual. Any other
individual or organization thereby should in no case change or modify the
manual.
4. Without our written permission, any organization or individual should not,
by the name of sale or donation, provide the public the manual or the
duplication of the manual.
5. Anyone who violates our copyright must be pursued according to the
copyright law.
Shanghai Lishen Scientific Equipment Co., Ltd.

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
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Table of Contents
I. Panel and functions of body fat measuring apparatus ..................................................................................... 4
II. Disassembly and maintenance of mechanical parts......................................................................................... 5
III. Steps on disassembly of body fat measuring apparatus................................................................................. 5
1. Turn the body fat measuring apparatus and unscrew 4 fittings.............................................................. 5
2. Open the lower cover:.................................................................................................................................. 6
3. Open the rear cover..................................................................................................................................... 7
4. The disassembly steps to check the bottom of upper cover...................................................................... 7
5. Bottom of backplane.................................................................................................................................... 8
IV. Introduction to circuit of body fat measuring apparatus............................................................................... 9
V. Functional description on sub-circuits:........................................................................................................... 11
1. MCU control circuit: ............................................................................................................................. 11
2. Power supply circuit:............................................................................................................................. 12
3. Sine wave generation circuit:................................................................................................................ 14
4. Differential detection circuit:................................................................................................................ 15
5. Auto calibration, diode connection, tetrode connection selection circuit: ........................................ 16
6. Crystal oscillator, key and LCD display circuit:................................................................................. 17
VI. Commissioning method and common troubleshooting................................................................................ 18
1. Commissioning condition...................................................................................................................... 18
2. Commissioning equipment.................................................................................................................... 18
3. Content and step of commissioning...................................................................................................... 18
3.1 Display commissioning ..................................................................................................................... 18
3.2 Auto shutdown and shutdown commissioing .................................................................................... 19
3.3 Commissioning on functional and accuracy test ............................................................................... 20
3.4 Commissioning on logging personal data function............................................................................ 20
3.5 Alarm commissioning........................................................................................................................ 20
3.6 Withstand test..................................................................................................................................... 20
4. Project mode............................................................................................................................................... 21
4.1 PWM differential value and standard resistance value...................................................................... 21
4.2 3V voltage and 5V voltage measurements......................................................................................... 21
5. Waveform measurement ........................................................................................................................... 22
6. Troubleshooting ......................................................................................................................................... 22
6.1 No display or missing stroke in the screen ........................................................................................ 22
6.2 Measurements of body fat rate deviates beyond ±2% ....................................................................... 22
6.3 With full illumination background after startup, it works ineffectively by pressing any key and the
apparatus is able to auto shutdown in 60sec. ........................................................................................... 22
6.4 PWM differential value and standard resistance measurements beyond the specified threshold or in
unstable condition.................................................................................................................................... 22

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
I. Panel and functions of body fat measuring apparatus
Front view of the apparatus:
6
54
3
2
1
电源
设定
测量
人体脂肪测量仪
基础
代谢
(kcal)
个人
号码
身高
体重
年龄
性别
低标准 偏高 高肥胖类型
Item Description Function
1 Electrode handle Weak detection current to be routed during test
2 Display area Display the settings and measurements
3 Test key After setting, push the key to start the test with appropriate
posture
4 Up and down keys Set the personal data (height, weight, age, sex).
Furthermore, you may select the personal code from 1 to
9.
5 Set key Set the personal code and data
6 Power key Turn on/off
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
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II. Disassembly and maintenance of mechanical parts
Maintenance tools
Big and small Phillips
screwdriver
Nipper pliers Art knife
Big and small flat tip
screwdriver
Diagonal cutting pliers Iron, solder stick
Tweezers
Unless otherwise specified in the disassembly diagram, the installation shall be progressed in the reverse sequence
as shown in the diagram.
Components and parts shall be only replaced with those from OEM and the maintenance people must follow the
graphic directions in the manual without modification at their discretion.
Note: On reinstallation following replacement of components and parts, each screw shall be painted
with thread adhesive before being fastened.
For maintenance, the body fat measuring apparatus shall be properly placed on the robust horizontal
table.
During the assembly:
1: All components and parts shall have the surface free of score, scratch, etc.
2: During the installation, please note the assembly location and direction of each component and
part.
III. Steps on disassembly of body fat measuring apparatus
1. Turn the body fat measuring apparatus over and unscrew 4 fittings.

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
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2
1
Item Description Quantity
1 Fitting 4
2 Housing of body fat
measuring apparatus
1
2. Open the lower cover:
1
2
Unscrew 4 cross tapping screws located at the lower cover, as shown in the diagram:

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Item Description Quantity
1 ST2.9*9.5 tin-coated tapping screw (Type F ) 4
2 Housing of body fat measuring apparatus 1
3. Open the rear cover
As shown in the diagram, detach the upper and lower covers, And be caution to make damage to the power wire
linking to the battery cable. to the power cable linking the battery. In case of need to removal of power cable, use
the iron to remove the cable.
4. The disassembly steps to check the bottom of upper cover
Step 1: Take off 7 screws as indicated in the diagram.
1
2
After the screws are removed, please properly keep them from loss.
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Item Description Quantity
1 ST2.9*7 tin-coated tapping screw (Type F ) 4
2 Upper cover of body fat measuring
apparatus
1
Step 2: Remove PCB board
2
1
Item Description Quantity
1 PCB board 1
2 Upper cover on housing of
body fat measuring apparatus
1
On removal of PCB board, please avoid damage to the power cable linking to the battery. It is advised to use the
iron to remove the cable and then the circuit board.
5. Bottom of Upper cover
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IV. Introduction on circuit of body fat measuring apparatus
4
General circuit diagram
Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
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3
2
1
Item Description Quantity
1 Key frame and
conductive rubber
1
2 LCD screen foaming
adhesive strip
2
3 Electrode pad 4
4 LCD screen 1

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Self-calibration, diode connection and tetrode connection selection circuit
Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Dia. <2-1> Principle diagram for prince 120 v1.1
Power supply circuit
Sine wave generation circuit
Differential detection circuit

Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
As shown in the diagram above, Prince 120 circuit principle diagram is divided into a) main
control MCU circuit (including LCD interface circuit and external crystal oscillator); b)
power supply circuit; c) sine wave generation circuit; d) self-calibration, diode connection and
tetrode connection selection circuit; e) differential detection circuit. These sub-functional
circuits will be described in details later.
Both hands hold the 4 electrodes at both ends of body fat measuring apparatus: RI and RV, LI and
LV. Alternating current is introduced to the human body via RI and LI terminal and then produces
output voltage from RV and LV terminals. When the voltage generated arrives at the differential
comparator circuit controlled by the analog switch CD4052, the voltage RV and LV from the analog
switch will obtain via differential comparator circuit (difference of RV and LV) a RI-superposed
sine wave identified as SIN_WAVE. The SIN_WAVE is compared with PWM which generated by
MCU during the operational amplification of MCP6541 and it may be calculated by successive
approximation approach via PWM at the analog terminal. Thus, it will produce an interruption at
high point and low point respectively. Then, the apparatus may calculates the resistance value
through the human body based on the resistance value which is corresponding to the voltage while
interruption
V. Functional description on sub-circuits:
1. MCU control circuit:
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Diagram<5-1>MCUcontrolcircuit
The diagram above shows the main control MCU chip circuit, which is designed to play the role of
the signal generating, DA sampling, LCD displaying and signal proceeding of body fat measuring. The
exact pins are defined below:
Pin Name Signal
(I/O)
Functional description
4 SIN WAVE I Sinusoidal signal reception and analog input terminal
8 TEST I Test key reception pin when low voltage enable
9 DOWN I Down key reception pin when low voltage enable
10 SET I SET key reception pin when low voltage enable
11 UP I UP key reception pin when low voltage enable
12 Battery V TEST I Battery voltage test pin when low voltage enable
13 POWER
ON/OFF T
I Power supply switch pin
14 DC-DC V TEST I Regulated power supply voltage testing pin
15 POWER ON
KEEP
I Startup stabilization testing pin
16 PROJECT
MODE
I Project mode control pin (controlled by JP1 jumper)
18 PWM O Analog voltage output pin
20 SDA I/O I2C circuit data pin
21 SCL O I2C circuit clock pin
23 Interrupt I External interruption pin
37~81 Cx, Sxx I/O LCD screen drive pin
97 B O Analog switch control pin
98 A O Analog switch control pin
99 50K Impulse O 50khz square wave pulse output pin
2. Power supply circuit:
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Diagram <5-2> Power supply circuit
As shown above, the circuit is designed to provide DC-DC voltage test function (DC-DC V TEST), POWER-ON
stabilization function and power-off control function in addition to the regular DC-DC step-up function.
The switch of the power supply circuit is controlled by S1. BT1 is the battery power supply of 3v. Battery V TEST
(the battery will be exhausted at about 2.4v and then display on the screen) is the test pin for voltage test.
connected to MCU analog terminal (MCU #12 pin), test voltage will judge whether there is power remaining at
less than 2.4v. PNP triode Q1 and NPN triode Q2 constitute the Darlington transistor that drive PFM switch-type
DC/DC step-up converter U1 ME2100A of low static current manufactured by CMOS process. The step-up
converter ME2100A may have voltage of pulse waveform at #3 pin while #2 pin is the output voltage (+5V,
voltage accuracy of ±2.5%).
When S1 is pressed for the 1st time, Q1 and Q2 work to drive U1 and output VCC.
When S1 is released for the 1st time, Q1, Q2 and Q3 work together and output POWER ON KEEP signal.
When S1 is pressed for the 2nd time, Q3 shutoff and POWER ON KEEP signal is lowered.
When S1 is released for the 2nd time, Q1 and Q2 shutoff and U1 stop work.
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
3. Sine wave generation circuit:
Diagram <5-3> Sine wave generation circuit
As shown above, the circuit is a generation circuit of sine wave of 50KHz and transmits, with the sine
wave, RI1 and LI1 to the human body in the way of current for test so as to allow U3 MCP6004
operational amplification to work within the appropriate range of amplification. Square wave of 50KHz,
generated by MCU #99 pin, may filter the low-frequency signal through a filter of high-pass filtering
circuit, and then reach the waveform generation circuit composed of power conductance L2, capacitor
C4 and C5.
With second-order filter composed of the conductance L2, capacitor C4 and C5, it is possible to see
the sinusoidal wave form at C4 and C5: at C4, it is possible to see the sine wave of high-frequency
component being not fully filtered while as at C5, it is possible to see the sine wave of 50KHz being
finally generated.
R10 bears the functions of limiting the output current so as to control the output current within the safe
range of the human body (less than 0.5mA). U3B MCP6004 is a follower and provides a stable
raising voltage of 2.5V (amplifier’s #7 pin) to be routed to MCP6004 #3 pin.
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
4. Differential detection circuit:
Diagram <5-4> Differential detection circuit
As shown above, the differential detection circuit is designed to allow RI1 and LI1 which is due to
produce voltage RV1 and LV1 generated by via U3’s operational differential amplification through
the human body, to output a differential-value sine wave SIN_WAVE at U3 #8 pin. The
differential-value sine wave is compared with PWM generated by MCU #18 pin, ie. To reduce the
SIN_WAVE value from the PWM’s fixed value (rise minimum voltage or reduce the maximum voltage). If
exceeding the value, output VCC voltage or maximum voltage. If beneath the value, output the minimum
voltage. The zero voltage may activate MCU’s external interruption pin (#23 pin INT1) and enable an
interruption. MCU will calculate the voltage value from the span of nearly two interruptions to obtain
the resistance value of human body’s resistance. The differential of RV1 and LV1 is to eliminate the
effect of surface resistance so that the obtained SIN_WAVE value is more accurate.
RV1 and LV1 are both the voltage as the current runs through the human body.
PWM is the square wave of 50KHz triggered by MCU #18 pin.
SIN_WAVE is the differential-value sine wave as generated differential of RV1 and LV1.
Interrupt is the external interruption pin of MCU and triggered on low level.
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
5. Self- calibration, diode connection, tetrode connection selection circuit:
Diagram <5-5> Auto calibration, diode connection, tetrode connection selection circuit
As shown above, RI, RV and LI, LV in the circuit are connected to the external electrode. The ring
circuit of the voltage and current is controlled and switchover by 2 analog switches. The ring circuit
is equipped with 3 selection channels, ie. auto calibration, diode connection, tetrode connection.
#9 and #10 pins of U6 and U7 selection channel control signal A and B are used to allow CD4052
analog switch to control the output and input terminals so as to select the different functions such as
self calibration, diode connection and tetrode connection and the purpose of measuring the
resistance across human body and self calibration.
The table below shows the value A and B and their combination of functions:
Input status
A B
Selection
channel pin
Function
0 0 x0,y0 Diode connection
0 1 x2,y2 Auto calibration
1 1 x3,y3 Tetrode connection
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
J1-J4’s 4 pin electrodes comprise 2 pairs of circuit for test of resistance across human body. With
the different switch combination of control pin’s A and B, it is possible to allow the AC signal of LI
and RI terminals to run into human body via current through the electrode and human body, which
may form a loop to enable the output voltage introduced to the differential comparator circuit for
resistance across human body.
Diode D3 –D9 are used for clamped purpose to protect the apparatus from static in the human body.
Resistance R24 and R25 are separately in parallel to pairs of current input and voltage output
terminals.
6. Crystal oscillator, key and LCD display circuit:
Diagram <5-6> Crystal oscillator, key and LCD display circuit
As shown above, the circuit is the interface circuit related to the output and display:
JP1 is the jumper of project mode: project mode is triggered when JP1 is connected. The jumper,
however, is detached before delivery.
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
S2, S3, S4, S5 keys: they are control keys located on the panel, namely up key, down key, set key,
test start key.
LCD interface (J5): the interface, made of carbon film and home-made zebra strip foaming rubber
strip, is the circuit to communicate with LCD screen so as to transmit the signal from MCU chip to
drive and control LCD screen.
Crystal oscillator circuit: MCU operates on start-oscillation based on the external crystal oscillation.
The external crystal oscillator has a frequency of 4.0MHz.
VI. Commissioning method and common troubleshooting
1. Commissioning condition
a) Environemntal temperature: +10℃--+30℃
b) Relative humidity: 30%RH-70%RH
c) Atmospheric pressure: 860hPa-1,060hPa
2. Commissioning equipment
Equipment Quantity
Oscilloscope 1
Signal generator 1
Resistance box 1
Big and small Phillips screwdriver 1 set
Universal meter 1
Leading wire Several
3. Content and step of commissioning
3.1 Display commissioning
Load with 2 AAA manganese/alkali dry batteries and press “Power” key, showing the fully
illuminated display for about 1sec. On full illumination, the complete contents shall be displayed in
the screen without any missing stroke. Presing the “Power” key may maintain the fully illuminated
display until release.
In case of any abnormal display shown in the screen, you may progress the maintenance as per
the instructions below:
1. After the “Power” key is pressed, the picture in full presentation is not available in LCD
screen:
Possible fault Troubleshooting
Power supply circuit is
working well
Check with universal meter if DC-DC power supply
ME2100A50P output #2 pin has correct output
voltage of +5V. In case of no output, check the
appropriate circuit, such as Q1, L1, Q2 and other
components.
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Crystal oscillator adjacent to
MCU is in start-oscillation
status
Check the crystal oscillator Y1’s pin with
oscilloscope for start-oscillation
Zebra strip is in good contact Take off the cover and unscrew 7 screws located on
PCB board as shown in Dia. 1. Check if foaming
zebra strips at both sides of LCD screen are placed at
the correct locations. If not, locate ther conductance
rubber strip correctly.
The chip’s displays are welded
properly
Check the chip pin for any defective welding.
Display screen is not assembled
correctly
There are 4 leading-out pins at the bottom of display
screen, which shall be properly identified.
“Power” key is working well Replace the conductance key film and check the
wiring of carbon film key.
Check if main chip
misfunctions
Replace the main chip.
2. After the “Power” key is pressed, unexpected pictures are shown in LCD screen, ie.
disordered graphics.
Possible fault Troubleshooting
Check that the display area of
display chip are wired correctly
Check with universal meter the pins at display side of
the chip and check the pins at drive LCD of the chip
for open circuit or short circuit.
Display chip damaged Replace the main chip.
Zebra strip is in good contact Take off the cover and unscrew 7 screws located on
PCB board as shown. Check if foaming zebra strips
at both sides of LCD screen are placed at the correct
locations. If not, locate ther conductance rubber strip
correctly.
3. When access to project mode, disordered graphics appear in LCD screen:
Possible fault Troubleshooting
Check that the display area of
display chip are wired correctly
Check with universal meter the pins at display side of
the chip and check the pins at drive LCD of the chip
for open circuit or short circuit.
3.2 Auto shutdown and shutdown commissioing
Auto shutdown: Press the “Power” key for startup. In case no key is pressed on the body fat
measuring apparatus for around 60sec., the apparatus will auto shutdown to show the contents in
full black background.
Shutdown: Press the “Power” key for startup. After a number of tests, press the “Power” key
for shutdown.
In case of any abnormal display shown in the screen, you may progress the maintenance as per
the instructions below:
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Maintenance Manual for Prince 120 Body Fat Measuring Apparatus
Possible fault Troubleshooting
Continuous welding of main
chip
Check (POWERE ON/OFF) pin.
3.3 Commissioning on functional and accuracy test
Disable two electrodes at both left and right side respectively with leading wires. Connect the
electrode of both sides to the resistance box with a leading wire, respectively and set the resistance
box to 720Ω. Turn on the power as per the “Operation Manual” to select “Guest”, fully selecting
the initial values (160.0cm, 60.0kg, 40 years old, male). After about 7sec. since pressing the “Test”
key, indicate the body fat rate of 26.9±2.0%, BMI of 23.4 and basal metabolism of 1,416.
With the above settings kept unchanged, carry out 3 tests continusouly and take the average of
shown body fat rates. If every test data varies from the average by not more than ±2%, the test is
acceptable.
3.4 Commissioning on logging personal data function
As per the “Operation Manual”, select the user no.1-9 in sequences under the user number
selection mode. With every number, you may set the different height, weight, age, sex, which data
will be stored. Recheck the data stored for user no.1-9.
On completion of commissioning, clear the stored data as per the “Operation Manual”.
3.5 Alarm commissioning
3.5.1 E1 alarm
Turn on the power as per the “Operation Manual”, select “Guest”, fully selecting the initial
values (160.0cm, 60.0kg, 40 years old, male). Both hands hold the handle as per the “Operation
Manual” and press the “Test” key. Release during the test and the measurements will show “E1”.
3.5.2 E2 alarm
Disable two electrodes at both left and right side respectively with leading wire. Connect the
electrode at both sides to the resistance box with a leading wire, respectively and set the resistance
box to 1,200Ω. Turn on the power as per the “Operation Manual” to select “Guest”, fully selecting
the initial values (160.0cm, 60.0kg, 40 years old, male). Press the “Test” key and the measurements
will show “E2”.
3.5.3 E3 and E4 alarm
Turn on the power as per the “Operation Manual” to select “Guest”, inputtig the following
parameters: 100.0cm, 91.0kg, 40 years old, male. Both hands hold the handle as per the “Operation
Manual” and press the “Test” key. Release during the test and the measurements will show “E3”
and “E4”.
3.5.4 Undervoltage alarm
Take off 2 AAA manganese/alkali dry batteries and use signal generator to produce a DC
signal of 2.35V/100mA. The negative pole of the DC signal is connected to –BK and the positive
one to +R. Press the “Power” key for startup, showing , which is acceptable.
3.6 Withstand test
It is required to withstand DC test voltage for 1min. without breaththrough or flashover.
DC500V appears between the electrical part and housing (A-a2);
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