Geometry Check - Philips PM32671 Service Manual

5.5.2.4. Focus and astigmatism
- Set the AMPL/DIV switch
- Depress 0 of S18.
- Set the MTB TIME/DIV switch S15 to 20p.
-
Depress ALT of S1.
- Set the trace of channel B in the vertical centre of the screen by means of the POSITION control R2.
- Set the FOCUS control R13 135' from i t s l e f t hand stop.
- Apply a sine-wave signal, frequency IOkHz,
Check that the traces are as sharp
-
ments of R13 (fig. 5.3.).
5.5.2.5. Geometry (barrel and pin-cushion distortion)
-
Depress A of S1.
- Set the AMPL/DIV switches
- Apply a sine-wave signal, frequency 1 OOkHz, amplitude x 800mVp-p to input A.
Adjust the trace height to 7.4 div. with R7.
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- Set the MTB TIME/DIV switch 515 to 50p.
- Apply a sine-wave signal, frequency
- Depress X DEFL of S2.
- Depress B of S23.
- Adjust the horizontal deflection to 9.4 div. by means of the continuous control R8.
- Check that the displayed vertical and horizontal lines are as straight as possible and check that the signal
falls between the hatched area shown in fig. 5.4.; if necessary readjust R1472 (fig. 5.3.).
- Remove the input signals.
Fig. 5.4. Geometry check
5.5.3. Balance adjustments
The balance adjustments of channels A and B are identical.
The knobs, sockets and adjustments of channel
5.5.3.1. Attenuator AMPL/DIV balance channel A (B)
- Set the controls as indicated in fig. 4.1.
- Depress A (B) of S1.
-
Depress 0 of S17 and S18.
- Depress A (B) of S23.
Set the trace in the vertical centre of the screen by means of POSITION control R 1 (R2).
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- Switch the AMPL/DIV control
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Adjust R547 (R747) for minimal trace jump, fig. 5.2.
- Switch the AMPL/D IV control S9 (S11) between the positions 1 OmV and 20mV.
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Adjust R571 (R771) for minimal trace jump, fig. 5.2.
5.5.3.2. Normal-Invert balance channel A (B)
- Depress A (B) of S1.
-
Put the AMPL/DIV control S9 (S11) in position 2mV.
- Set the trace in the vertical centre of the screen by means of POSITION control R1 (R2).
- Pull and push the normal-invert switch
- Adjust R604 (R804) for minimal trace jump, fig. 5.2.
6 div, trace height to input A.
possible; if necessary optimise with the aid of
as
MAT 981 A
are shown in brackets behind those of channel A.
5-13
and small readjust-