Continuous RMS
power output (Reference) 50 W + 50 W (6 Ω at 1 kHz, 10% THD)
HCD-GRX20-RXD3 is the tuner, deck, CD and amplifier section in MHC-GRX20-RXD3.
CD Mechanism Type: CX3
Base Unit Type: KSM-213ECM
Optical Pick-up Type: KSS-213ECM-C2NP
Tape Transport Mechanism Type: CWL-44-FR
Continuous RMS power output (Reference): 50 W + 50 W (6 Ω at 1 kHz, 10% THD
AM tuner section
Tuning range: 531 – 1,602 kHz (with AM tuning interval set at 9 kHz) 530 – 1,710 kHz (with AM tuning interval set at 10 kHz)
Antenna: AM loop antenna
Antenna terminals: External antenna terminal
Intermediate frequency: 450 kHz
TEST MODE
Initialization
STOP + POWER OFF All preset data is re-set to the initial (default) value.
Model display
STOP + DISC 1 Mode name is displayed.
Destination display
STOP + DISC 2 Destination is displayed.
Version display
STOP + DISC 3 Version number of the microprocessor is displayed.
CD aging mode
STOP + DISC SKIP/EX-CHANGE Set discs to DISC 1 and DISC 3. The following operations are repeated when aging starts:
1. DISC 1: TOC Read
2. Plays back the last music of the DISC 1.
3. DISC 3 : TOC Read
4. Plays back the last music of the DISC 3.
5. STOP
6. Tray is open and closed.
TAPE aging mode
STOP + PLAY A Insert a commercially available cassette tape (10 min) to the decks A and B. When aging starts, each tape is rewound and the following operations are repeated:
1. TAPE A: FWD PLAY for one minute
2. TAPE A: FWD STOP for one second
3. TAPE A: FWD PLAY for three minutes
4. TAPE A: FWD FF to tape end
5. TAPE B: FWD PLAY for one minute
6. TAPE B: FWD REC PAUSE for one second
7. TAPE B: FWD REC for three minutes
8. TAPE B: FWD FF to tape end
9. TAPE B: REV PLAY for one minute
10. TAPE B: REV REC PAUSE for one second
11. TAPE B: REV REC for three minutes
12. TAPE B: REV FF to tape end.
CD service mode
STOP + OPEN/CLOSE The message “CD S - -” is displayed on the screen. The sled is moved to the outer circumference while the FF button is pressed. Also, the SLED is moved to the inner circumference while the REW button is pressed. After pressing the PLAY button, FOCUS is turned ON, CLV-S is set, TRACKING and SLED servos are turned OFF and ADDRESS 3 = 3F, 37 is set.
Display
STOP + DBFB All displays are turned ON.
Balance adjustment value
STOP + DISPLAY/DEMO The balance adjustment value is displayed.
Key check
STOP + FILE SELECT Function of the pressed key is displayed.
MECHANICAL ADJUSTMENTS
1. Clean the following parts with a denatured alcohol-moistened swab:
Record-playback head, pinch rollers, erase head rubber belts, capstan idlers.
2. Demagnetize the record/playback head with a head demagnetizer.
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, apply suitable locking compound to the parts adjusted.
5. The adjustments should be performed with the rated power supply voltage unless otherwise noted.
Torque Measurement
ELECTRICAL ADJUSTMENTS
DECK SECTION: 0 dB=0.775V
1. Demagnetize the record/playback head with a head demagnetizer.
2. Do not use a magnetized screwdriver for the adjustments.
3. After the adjustments, apply suitable locking compound to the parts adjusted.
4. The adjustments should be performed with the rated power supply voltage unless otherwise noted.
5. The adjustments should be performed in the order given in this service manual. (As a general rule, playback circuit adjustment should be completed before performing recording circuit adjustment.)
6. The adjustments should be performed for both L-CH and RCH.
Record/Playback Head Azimuth Adjustment (Deck A, Deck B)
[Perform these adjustments for both decks.]
AM Tuning Voltage Adjustment
1. Set the reception frequency of the unit to 530 kHz.
2. Adjust L105 for 1.2 ± 0.05 V reading on the DC voltmeter.
3. Set the reception frequency of the unit to 1,710 kHz.
4. Confirm that the voltage reading on the DC voltmeter is within 8.0 ± 0.5 V.
Adjustment Location: MAIN board.
AM Tracking Adjustment.
1. Tune the set to 600 kHz.
2. Set the output of AM RF SSG so that the input level of the set will become 60 dB (µV/m).
3. Adjust L104 so that when the waveform on the oscilloscope is maximum, no noise appears.
4. Tune the set to 1,400 kHz.
5. Adjust TC102 so that when the waveform on the oscilloscope is maximum, no noise appears.
Repeat the procedures in each adjustment several times, and the tracking adjustment should be finally done by the trimmer capacitors.
Adjustment Location: MAIN board.
FM Tuned Level Adjustment
1. Supply a 28 dB 98 MHz signal from the ANTENNA terminal.
2. Tune the set to 98 MHz.
3. Adjust SFR101 to the point (moment) when the TUNED indicator will change from going off to going on.
Adjustment Location: MAIN board
CD SECTION
1. CD Block is basically constructed 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 10MΩ 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.
5. Adjust the focus bias adjustment when optical block is replaced.
1. Connect oscilloscope to test point TP (RF) on CD DECODER board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Confirm that oscilloscope waveform is clear and check RF signal level is correct or not.
Note: Clear RF signal waveform means that the shape “◊” can be clearly distinguished at the center of the waveform.
Circuit diagrams
