- 7 -
Trouble shooting ECR V1.01
2-2-2. Procedure Repair 1
1) Check that contact of CPU defective. ( For example, pin of CPU is floating. )
2) Check that the power supply is supplied to CPU.
( For example, the cables between the CPU and the power supply are snapping. )
3) Check “X1” of oscillator whether the signal of wave form is as follow.
( If not, resolder the connection point or replace “X1” of oscillator. )
4) Check “IC10” of CPU.
( If there are no signal at the X1, resolder the connection point or replace “IC10” of CPU. )
2-2-3. Procedure Repair 2
1) Visually check on the Main P.C.Board.
( For example, cold solder and surface flaw. )
2) Check the data bus line and the address line of CPU. If there are a problem signals at the
line, find out the reason and change the problem IC. (The each signal should be a digital signal
like a following pulse wave form. If you see the voltage level is not +5V or 0V, find out the
problem IC to follow the line. For example, change the IC7 of SN74LV374 address latch.)
CPU clock X1
VDD +5V
GND 0V
Data bus line D0
Data bus
CPU clock X1 wave form
CPU Data bus D0 line wave form
CPU clock X1
