Zhangshan Hengxing Electronic Co., Ltd.
Address:2 Yongqiang Rd, Zhaolong Industrial Park,Dongsheng Zhongshan-528414 Guangdong China
Tel:0760-22821378
0760-22229872
0760-22224078
Fax:0760-22229873
Zip code:528414
E-mail:hx@hengxinhengqi.com
Troubleshooting
(!)Tips
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Preface: Electronic scale is a weighing instrument contains electronic devices, it displays weight information by numbers. It is made up of many components, such as load cell, computing amplifier, A/D integrated circuit, SCM, display driver and circuit, keypad circuit, interface circuit, AC/DC/Power storage/Power regulator circuit. So, problem may occur and different from time to time.
1. No return zero
a. Check if the signal from Load cell within its scope.(Max value/operation value/Min value of the A/D)
b. If the value is beyond the scope, please refer to section 10.
c.If unable to compensate, please check the load cell. (please refer to section 8)
d. Please refer to the instructions of the operation manual to calibrate.
2. Inaccurate weighing readings
a. Check if the value is stable, if the load cell is abraded, if the power is stable, if the circuit is OK, if there is alien particles inside the A/D PCB, or if there is malfunction or power leakage of the resistor/capacitor/filter capacitor.
b. Check if the signal from Load cell within its scope
c. If the value is beyond the scope, please refer to section 10.
d. Add weight to each corner of the pan, check if the weight readings are close or the same.(if not, please refer to section 9 to calibrate)
e. Please refer to the instructions of the operation manual to calibrate.
3. Unable to turn on
a. Firstly be sure that the fuse, switch, power cable and transfer switch are OK.
b. Take out the battery and connect the scale with AC power, restart the scale to check if the battery is the cause. (The battery voltage should above 6V, if not, please recharge, or change battery)
4. Display problem
a.Connect another new LCD to the testing equipment and check if there is the same problem, if not, the old LCD is malfunction.
b. Check if the CPU pin is oxidated, unsoldered or short circuit.
c. Check if the LCD pin is oxidated, unsoldered or short circuit.
d. Check if the cable between CPU and LCD is short circuit.
5.Keyboard problem
a.Please test another new K/B(keyboard) to check if the old one malfunction.
b. Check the cable between K/B and CPU to see if there is short circuit or unsoldered.
c. Check if the K/B pin has bad contact.
d.Check if the audion Q3,Q5 between K/B and CPU is damaged.
6. Unable to full load
a.Check if the signal from Load cell within its scope
b. If the value is beyond the scope, please refer to section 10.
c. If unable to compensate, please check the load cell. (please refer to section 8)
d. After compensation, change load cell if the reading still unstable or unable to compensate.
e. Check if there is interference inside.
7. The battery unable to store power.
a. Firstly be sure that the fuse, switch, power cable and tansfer switch are OK.
b. Check if the transformer output 9V voltage.
c. Take off the PIN, check if the scale PCB charging voltage is around 6.8V, if not, check the power supply circuit.
d. Change the battery if battery voltage is below 5V.
8. Identify Load Cell problem
a. Method a: use multimeter to check if the resistor value E+ VS S+(or E- VS S+、S-)is close or the same, if the error is above 0.5Ω,then need compensation, if the error is above 2Ω, change load cell.
b. Method b: connect the load cell with motherboard of the scale, set multimeter at DCV to check if the reading S+ VS S-, is the same, if not, compensation is needed.
9. Angular Difference Adjustment(single load cell)
a. Weighing adjustment.
b. Place 1/3 of the full load weight to test the four corners of the pan, check the readings. from the display. c. Use file to abrade the corner with the minimum reading, then press Tare/Zero key.(when do it for the first time, in order to avoid damage to the load cell, please use less strength and abrade gently) d. Repeat step 2~3 until the error range of the readings of the four corner is within ±1, then do the weighing adjustment.
e. If the error of the readings are too large even after abrasion, this means the load cell is malfunction or the way you abrade the scale is incorrect.
f. Please pay attention to the specification of the load cell, the smaller the full load capacity, the lesser strength should be used in abrasion.
10. Compensate the Load Cell
a.If the signal from the load cell makes the reading too large, add one resistor (50K~2.2MΩ, depend on actual situation) between " E+S- "(The lower resistor value, the smaller reading signal from the load cell)
b. If the signal from the load cell makes the reading too small or even make the screen displays –ERR, add one resistor (50k~2.2MΩ, depend on actual situation) between "E+S-".(The lower resistor value, the bigger reading signal from the load cell).
