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Thanks you very much for this "hard to find" service manual.
Will help a lot in repairing this tuner.
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I have this hi-fi system for a long time and I need to repair some things. Founding this manual will be very helpfull :)
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It is pretty good. The schematics were covered all components, the manual also provide the parts list . It's useful for the trouble shooting.
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Very fast service, best quality of the service manual and the schematics
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This service manual of the old video cassette recorder VT-LC50EM is very good readable even the tiniest numbers (i.e. IC-pins). The circuits are very clear. Many details of the schematic are very good described but in GERMAN language. Many schematic details - but complete at all. Common background information of several details are enclosed and physical knowledge of the TFT liquid crystal display for example. The manual lacks PCB drawings. If you understand german I would recommend this manual for you.
AV-28BK5ECB AV-28BK5ECS CHASSIS DESCRIPTION
[Digital Scan Operation]
100Hz Digital Scan Converter circuit 100Hz converter circuit consists of the following ICs. - TC90A36F, IC7201 Field Progressive Converter - MSM518221A, IC7202, IC7203 Video Memory - TLC2932I, IC7204, IC7205 PLL (Phase Locked Loop) - MC74HC04AFP, IC7341 invertor The Y-signal output from IC101 is sent to pin 85 of IC7201<TC90A36F>, field progressive converter, after controlling the amplitude level and band-pass limiting by the circuit consist of Q7301, Q7302, Q7303, Q7304 and 8MHz LPF. The U/V-signal are also controlling the amplitude level and band-pass limiting by the circuit consist of Q7311, Q7312, Q7313, Q7314, Q7321, Q7322, Q7323, Q7324 and 4MHz LPF respectively. The U-signal is sent to pin 90 of IC7201and the V-signal is sent to pin 92 of IC7201. The HD signal is sent to pin 63 of IC7201 with positive polarity through IC7341 for shaping the waveform. The VD-signal is sent to pin68 of IC7201 with negative polarity through IC7341. The Y-signal input to IC7201 is converted from A to D in 8bit and output from pins 31 to 50 of IC7201 to pins 1 to 4 and 24 to 27 of IC7203<MSM51822A>, video memory, for writing. Digital scan circuit
LPF Q7351-Q7354 LPF Q7361-Q7364 LPF Q7371-Q7374
IC7203 IC7202
6 9 | 31
2Y 2U 2V
98
100
IC7201 DOUBLE SCAN CONVERTER <TC90A36F>
31 | 50
92
LPF Q7321-Q7324 LPF Q7311-Q7314 LPF Q7301-Q7304
V U
90
Video Memory
85 53 59 63 68 70 71
Y
IC7204 PLL <READ>
9 4
IC7341 Inverter
13 12 11 10
2HD 2VD VD HD
IC7205 PLL <WRITE>
5 4
6 4
5 1
Fig.-6
6
No. 51758
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