Mpu Operation Error - NEC DPro2070SB Service Manual

3.4.8 MPU Operation Error

Check the 5V line.
NG
OK
Check the reset voltage.
NG
OK
Check the waveform at Pins 17 and 18 on the MAIN PWB.
NG
OK
Check the sync. signal.
NG
Check sync. failure. (See Item 3.2.3)
OK
Expected failure point
IC102 on the MAIN PWB
Check the voltage at Pin 3 of IC100 on the MAIN PWB.
Expected failure point
The power circuit (See Item 3.4.1)
Confirm that the voltage at Pin 12 of IC102 on the MAIN PWB is maintained at approx. 5V.
Expected failure point
IC100 on the MAIN PWB or C100
Expected failure point
X100 on the MAIN PWB or IC102
Confirm that there are horizontal sync (5Vp-p) input to Pin 36 and
vertical sync. (5Vp-p) input to Pin 33 of IC102 on the MAIN PWB.
Expected failure point
Confirm that a sinusoidal waveform of approx. 3
to 5Vp-p is generated at a frequency of 20MHz.
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