ST-800/900
Maintenance manual
10
11.3
、
Chart 3: The maintenance of the counting tube operating circuit
11.3.1
、
Emitting tube
The maintenance of the emitting tube operating circuit
11.3.2
、
Receiving tube
The maintenance of the receiving tube operating circuit
In the batching mode, input “1.2.3.4” then press “RESET”; when the display
show “ U00 A00”, measure the voltage between the 1
st
and 2
nd
and the voltage
between 3
rd
and 4
th
pin of J15 by the use of digital multimeter, and the voltage
is around 1.14V.
Whether the emitting tube is damaged or not
N
The voltage of b pole of Q8 is around
4.11V, and the voltage of the 30
th
pin
of CPU is around 0.05V.
N
Y
CPU is damaged
Replace the emitting tube
Y
Q8 is damaged
N
Replace the main board
