7.5 The span value / internal value is unstable
n
Check the load cell itself. If necessary, replace it.
o
Check the main board if there are any oxidation. If necessary, clean the PCB by
cleaning supplies.
7.6 Charging control lamp is always red or scale does not charge
n
Measure the voltage of the battery. If necessary, replace it.
o
Measure the output voltage of the transformer (AC 10V). If necessary, replace it.
p
Measure the output voltage of the bridge regulator (DC 10V). If necessary, replace
it.
q
Measure the IC TIP31C at Q1 – 1
st
and 2
nd
pin must be at 6-8V. If necessary,
replace it.
r
Check zener diode D2 and resistor R17. If necessary, replace it.
s
Measure the IC LM723 at U4 – 3
rd
pin must be at 6.8 - 1.15V, 4
th
pin must be at
3.2 - 3.4V, 5
th
pin must be at 3.7 - 4.2V and 6
th
pin must be at 6.8 - 7.4V. If it is
abnormal, replace the IC LM723.
t
If all points above are o.k. check the IC 975 at Q7. If necessary, replace it.
18
RXB-SH-e-0710
