Olivetti ECR 8220, Руководство по обслуживанию

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3-4. RESET CIRCUIT
The reset circuit prevents the CPU from starting to operate before the system is fully powered-up
and initialized. Then 29m sec. after power is applied, reset goes high and the CPU can begin
functioning.
When power is first applied to the circuit, the VBB begins charging C141 a capacitor.
Output of Reset IC(U10) is low-resistance at VBB-Line is less than 3.0 Volts.
RE SE T
R107
4.7K
RESET#
RESET#
VBB
VBB
VOUT
1
VDD
2
GND
3
N.C.
4
C.T.
5
U10
BD5230G-TR
C29
0.1uF
C141
4700pF
TP11
RST
(1)
Trouble shooting
- When power ON but no display / any key operation unable.
Check the voltage at point (1)
DC +3.3V - - - Reset circuit is OK. The problem may come from other causes.
Check the Power supply circuit again and replace Main board
if no problem found in the power supply circuit.
0V - - - Reset circuit has a problem. Replace Main board.
Service Manual 40