Sharp QD-101MM, Service Manual

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6
7) Turn on the power. Observing the oscilloscope, adjust the TP305 level to be equal
to TP300 level by turning VR302 with the flat-tipped screwdriver.
2.3.VCO adjustment
1) Connect the + lead of the DC voltmeter to TP207, and the - lead to TP10.
2) Input the video timing of Fig. 1-A to J2.
3) After turning on the power, leave it as it is for approx. 3 minutes.
Then turn L200 with ceramic driver to adjust the voltage of TP207 to 2.5
±
0.2V. (*1)
4) Input the video timing of Fig. 1-B or C to J2 .
5) Then turn L201 with ceramic driver to adjust the voltage of TP207 to 4.1
±
0.05V. (*2)
(*1) Since the voltage of TP207 varies depending on the material of the driver used,
keep the driver away from the core when checking the voltage.
(*2) It is factory-adjusted at the timing of PC9801 640X400 at shipment.
2.4.Audio speaker level adjustment
1) Input the 1KHz, 500mV(RMS) sine wave from an oscillator to the audio signal input
terminal CN502.(The audio signal level should be adjusted when power switch of QD-
101MM is on.)
2) Set the volume level to maximum and the audio mute switch to off.
3) Connect an effective value type AC voltmeter to TP502 and adjust the voltage of TP504
to 2.85V(RMS) by turning VR501 with the flat-tipped screw driver.
Video
Video
Hsync
Vsync
95 64 113 640dot
1H=912dot=63.696047µs
25 3 34 200H
(1/H=15.699561KHz)
(1/V=59.92Hz)
1V=262H=16.688364ms
Fig. 1-A IBM CGA 200-line 40-character