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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.
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Hi, this is a very clear manual, nice copy, not quite up to the standard of the very best available but better than many others. I think the price was especially fair for a hard to find manual and I would certainly use this manual seller again. Recommended.
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This schema available for me in good condition. I would highly recommend.
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Thanks for this "hard to find" service manual.
I apreciate the good quality of scanning and the pages scanned in A3 format.
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Helpd me mont a new carradio when prewius mont was a mess.
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1.1.3 Focus error amplifier
The photo-detector outputs (A + C) and (B + D) are passed through the differential amplifier and the error amplifier, and (A + C - B - D) is provided from the pin 135 as the FE signal. The low frequency component of the voltage FE is calculated as below. FE = (A + C - B - D) x 8.8k / 10k x 111k / 61k x 160k / 72k = (A + C - B - D) x 3.5 For the FE outputs, an S-shaped curve of 1.5 Vp-p is obtained with the REFO as the reference. The cutoff frequency for the subsequent stage amplifiers is 14.6 kHz.
A
1.1.4 RFOK circuit
This circuit generates the RFOK signal, which indicates the timing to close the focus loop and focus-close status during the play mode, from the pin 70. As for the signal, "H" is output in closing the focus loop and during the play mode.
B
Additionally, the RFOK becomes "H" even in a non-pit area, since the DC level of the RFO signal is peak-held in the subsequent digital block and compared at a certain threshold level to generate the RFOK signal. Therefore, the focus is closed even on a mirror-surface area of a disc. This signal is also supplied to the microcomputer via the low-pass filer as the FOK signal, which is used for protection and gain switching of the RF amplifier.
1.1.5 Tracking error amplifier
The photo-detector outputs E and F are passed through the differential amplifier and the error amplifier to obtain (E - F), and then provided from the pin 138 as the TE signal. The low frequency component of the voltage TE is calculated as below.
C
TEO = (E - F) x 63k / 112k x 160k / 160k x 181k / 45.4k x 160k / 80k = (E - F) x 4.48 For the TE output, TE waveform of about 1.3 Vp-p with the REFO as the reference. The cutoff frequency in the subsequent is 21.1 kHz.
CD CORE UNIT
PE5611B
TE A/D
+ -
Pickup Unit
D
P5 P10
+ -
TEOFF setup
+ 80k
138
TEO
47p
160k 137
TE-
E
11
11
E
132 112k 63k
45.36k
161k
VREF
+ 45.36k
+ -
139
TE2
2.7k
+
P1 P6
-
160k
160k 20k 60k 10000p 140
1000p
F
9
9
F
131 112k 63k
TEC
-
VREF
+
Inside TEC
E
Fig.1.1.3 TE
F
6
CX-3240
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