3-6. Vertical Sync Frequency Identification Circuit - Sony Trinitron Multiscan CPD-1302 Service Manual

.'
SONY:
Technic.1 Oep.rtment
Sony Service Company
A D,v,s,on of Sony Corporation of America
Sony
Dme.
Park Ridge. New Jersey 07656
.0
color Iv
Serv ice Bu II et in No.303
Model:
CPD-1302
Subject:
Only Green Text Displayed Or
Muted Picture
Oate:
October 9, 1987
Using EGA Card only green text is displayed or occasionally no
display at all when the vertical frequency is 55-57Hz. The
50/60Hz switching circuit does not respond correctly to the
i ncomi ng signal.
Solution:
3-6. Vertical Sync Frequency Identification Circuit.
1) Preliminary CPD Generator Setting
1. Input signal H: 15. 734KHz
~H:
<ID
®
V: 60Hz ~V: (7) (g)
2. Set switch position to D1.
3. Connect a digital voltmeter to BA board Q332/BASE and ad-
just RV306 so the voltage value is 5.6VtO.05V DC.
4. Set switch position to D2 (or short between BA-3 pin 1
(MS pin) and ground).
5. Adjust RV307 so the "BA" board Q332/BASE voltage value is
6.6VtO.05V DC.
2) Precise CPD Generator Setting For V: 55. 13Hz Switch-Over Frequency
1. Input signal H: 18.41KMz
~H(D
®
V: 55.13H -.V
®
@
2. Set switch position to D2 (Green Bars should appear on screen).
3. Connect a digital voltmeter to "BA" board Q332/BASE and very
slowly increase the voltage with RV307 until relay CLICK is
heard and GREEN BARS change into COLOR BARS. The voltage'
would be approximately in 6.7--6.8V range.
(Continued)
2CTV1087-8
Prrnled ,n USA
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