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Happy to find finally a schematic for this amplifier. The schematic is of good quality, the pcb layout is useless: all is black. Never the less, it is very easy to find the components on the board using the schematics.
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Hard to find manual was ready the next day. Scans were very legible (including schematics). All the essential parts of the service manual were present (adjustment procedure, schematics, and parts list). It would have been nice if the rest of the manual was included (disassembly procedure, theory of operation, etc.).
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The Service Manual for the Kenwood KR-V55R provided by owner-manuals.com was as described/advertised. The contents provided the necessary information to effect a diagnosis of the unit. The schematics above all else was instrumental in tracing the the signal flow from component to component.
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This manual was the factory original. Excellent value and contained all the details I needed. Easy dowwnload provided the information when I needed it.
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Impeccable, document très complet. Perfect, i get all i need. All schematic are correct. Thanks
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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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