Check item(3-6.4.). Check the communication line :
Check the CPU.
Is the waveform of the TP near the DIR [IC761] correct (like the one
shown in the diagram) when the power is turned on?
IC761
DR_CE
DR_DOUT
DR_DIN
DR_CK
Check item(3-6.5.). Check the communication line :
Check DIR [IC761], CPU[IC751] patterns as well as soldering.
If there is no problem, go to the next step.
Check the communication line.
DIR [IC761] is faulty.
Replace with a new device.
YES
*The diagram shows an example.
(Signal patterns vary depending on the
timing.)
Points for checking waveforms
- Crest value (3.3V normally)
- Signal change
- CLOCK frequency (about 2MHz)
Voltage scale：2.0V/div
Time scale：2us/div
NOYES
Recheck from check item (3.1.).
If it does not work, replace the PCB.
Before Servicing
This Unit
Electrical Mechanical Repair Information Updating
96
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