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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.
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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.
SECTION 5 ELECTRICAL ADJUSTMENTS
Note: 1. CD Block is basically designed to operate without adjustment. Therefore, check each item in order given. 2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated. 3. Use an oscilloscope with more than 10M� impedance. 4. Clean the object lens by an applicator with neutral detergent when the signal level is low than specified value with the following checks. S-Curve Check
oscilloscope BSL board TP (FE) TP (VC)
+ �
Note: A clear RF signal waveform means that the shape ��� can be clearly distinguished at the center of the waveform.
RF signal waveform
VOLT/DIV: 200 mV TIME/DIV: 500 ns
level: 1.2 +0.25 Vp-p �0.20
E-F Balance (1 Track Jump) Check
oscilloscope
Procedure: 1. Connect the test point TP (ADJ) on MAIN board to the ground with a lead wire on MAIN board. 2. Connect oscilloscope to test point TP (FE) on BSL board. 3. Turned Power switch on to set ADJ mode by TIMER SW OFF. 4. Put disc (YEDS-18) in and turned Power switch on again and actuate the focus search. (actuate the focus search when disc table is moving in and out.) 5. TIMER SW ON. 6. Press the �1� button (s-cuve observe mode). 7. Check the oscilloscope waveform (S-curve) is symmetrical between A and B. And confirm peak to peak level within 3 ± 1 Vp-p.
S-curve waveform
symmetry
BSL board TP (TE) TP (VC)
+ �
Procedure: 1. Connect oscilloscope to test point TP (TE) on BSL board. 2. Turned Power switch on. 3. Put disc (YEDS-18) in to play the number five track. 4. Press the �P (Pause)� button. (Becomes the 1 track jump mode) 5. Check the level B of the oscilloscope�s waveform and the A (DC voltage) of the center of the Travers waveform. Confirm the following : A/B � 100 = less than ± 6 (%)
1 track jump waveform
A within 3 ± 1 Vp-p B
Center of the waveform B A (DC voltage)
Note: � Try to measure several times to make sure that the ratio of A:B or B:A is more than 10:7. � Take sweep time as long as possible and light up the brightness to obtain best waveform. RF Level Check
0V level : 1.5
+1.5 �0.5
Vp-p
symmetry
E-F Balance Check
oscilloscope
oscilloscope BSL board TP (RF) TP (VC)
+ �
BSL board TP (TE) TP (VC)
+ �
Procedure: 1. Connect oscilloscope to test point TP (RF) on BSL board. 2. Turned Power switch on. 3. Put disc (YEDS-18) in to play the number five track. 4. Confirm that oscilloscope waveform is clear and check RF signal level is correct or not.
Procedure: 1. Connect the test point TP (ADJ) on MAIN board on the ground with a lead wire on MAIN board. 2. Connect oscilloscope to test point TP (TE) on BSL board. 3. Turn the Power switch on to set the ADJ mode. (TIMER SW OFF) 4. Put disc (YEDS-18) in to play the number five track. 5. Press the �3� button. (The tracking servo and the sledding servo are turned OFF.)
� 16 �
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