Horizontal Oscillation /Deflection Circuit Failure - NEC DPro2070SB Service Manual

3.4.2 Horizontal Oscillation /Deflection Circuit Failure

(Check "3.1 No Raster Generated" and "3.2.3.1 Horizontal Sync Unstable" before this item)
Check the 215V line.
NG
OK
NG
Check horizontal drive pulse.
OK
Check the drive pulse.
NG
OK
Check the waveform at the
base of Q550.
OK
Check the drain waveform at Q5F1.
Check the range of horizontal oscillation.
OK
Q501, Q502 or Q503 on the MAIN PWB, or peripheral circuits
NG
Expected failure point
IC601 on the DEFL-SUB PWB or peripheral circuits
Check the voltage at Pin 1 of CN9A0 on the MAIN PWB.
Check the 215V line again after jumper in Pin 1 of CN9A0 line has been removed.
*Notice: When reconnecting CN9A0, confirm that Pin 1 has discharged electricity.
OK
Q5F0, Q5F1 or IC5C0 on the MAIN PWB, or peripheral circuits
Expected failure point
Switching power circuit (See Item3.4.1)
Measure the drive pulse voltage at the gate of Q504 on the MAIN
PWB, and confirm that there is a rectangular output of 10Vp-p.
NG
Q504 or D501 on MAIN PWB, or peripheral circuit
NG
Q550, T501, D502 or D550 on the MAIN PWB, or peripheral circuits
NG
Q5F0, Q5F1 or IC5C0 on the MAIN PWB, or peripheral circuits
Confirm that the voltage waveform of Pin 11 of CN601 on the MAIN
PWB is approx. 1Vp-p.
Expected failure point
Expected failure point
Measure the drain voltage at Q504 on the MAIN PWB, and
confirm that there is a rectangular output of 40 Vp-p.
Expected failure point
Measure the voltage waveform at the base of Q550 on
the MAIN PWB, and confirm that there is a rectangular
output of about 10Vp-p.
Expected failure point
Check the drain voltage waveform of Q5F1 on the MAIN PWB,
and confirm that there is a waveform output as shown below.
Approx.
215V
Expected failure point
3-19
Horizontal duration
Horizontal period