Power On Ng - Oki OKIFAX4550 Maintenance Manual

4.4.14 Power ON NG (01)

14: Power ON NG (01)
Check CN1, RAM3, IC2,
IC1, FLS, CPU solderling.
Good
Check appearance of
G4N board.
Good
Waveform of pins 51, 50,
27 of RAM3 are similar
to Figure H.10(1/3).
Yes
Waveform of pins 1, 6, 7,
17 of RAM3 are similar
to Figure H.10(2/3).
Yes
Waveform of pins 51, 46,
45, 27 of RAM3 are similar
to Figure H.10(3/3).
Yes
Waveform of pins 75, 76,
79 of IC2 and pin 53 of CPU
are similar to
Figures H.11(1/3,2/3).
Yes
Waveform of pins 75, 79
91 of IC2 are similar
to Figure H.11(3/3).
Yes
Waveform of pins 12, 14,
43, 15 of FLS are similar
to Figure H.9.
Replace CPU chip.
Yes
Re-loading G4A program
by PC-loading.
Bad
Replace G4N board.
41309401TH Rev.4
LCD display "ISDN BOARD I/F ERROR"
at power on.
Bad
Re-solderling
Bad
Modify bad point
No
Check CN1 solderling
No
Replace RAM3
No
Replace RAM3
No
Replace IC1
No
Replace IC2
No
Replace FLS and
re-loading G4N program
Good
Flash memory failure
574 /