Sony TMR-RF875R Service Manual
TMR-RF875R
SERVICE MANUAL
Ver 1.0 2000. 08
TMR-RF875R is the component model block one in the MDR-RF875RK.
COMPONENT MODEL NAME FOR MDR-RF875RK
Headphones MDR-RF875R
Transmitter TMR-RF875R
AEP Model
UK Model
SPECIFICATIONS
General
Carrier frequency
863.5 – 864.5 MHz
Channel Ch1, Ch2, Ch3
Modulation FM stereo
Frequency response
18 – 22,000 Hz
Transmitter
Power source DC 9 V: supplied AC power
adaptor
Audio input phono jacks/stereo mini jack
Dimensions Approx. 130 × 135 × 150 mm
(5 1/4 × 5 3/8 × 6 in.) (w/h/d)
Mass Approx. 200 g (7 oz.)
Design and specifications are subject to change without
notice.
TRANSMITTER
Setting up the
transmitter
1
Connect the transmitter to audio/video
equipment. Select one of the hookups
below depending on the jack type:
A To connect to a headphone jack
SECTION 1
GENERAL
This section is extracted
from instruction manual.
Transmitter
OFF ON
FILTERNOISE
Right channel
(red)
Connecting cord
(supplied)
Unimatch plug
adaptor
(supplied)
to headphones
jack (stereo
phone jack)
RBAL
AUDIO IN
CD Walkman,
MD Walkman,
WALKMAN*,
VCR, etc.
to AUDIO IN
A jacks
DC IN 9V
123
CHANNEL
Left channel
(white)
to headphones
jack (stereo
mini jack)
Flexible Circuit Board Repairing
• Keep the temperature of soldering iron around 270˚C
during repairing.
• Do not touch the soldering iron on the same conductor of the
circuit board (within 3 times).
• Be careful not to apply force on the conductor when soldering
or unsoldering.
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be
damaged by heat.
— 2 —
SECTION 2
)
)
DISASSEMBLY
Note : Follow the disassembly procedure in the numerical order given.
2-1. HOUSING (UPPER)
2
Housing (upper)
1
Four screws (P 2
× 8)
2-2. TX-BASE BOARD
Housing (upper)
Screw
3
TX-BASE board
2-3. CHG-NR BOARD
Housing (upper
2
2
CHG-NR board
1
Screw (P 2
× 6
— 3 —
1
Four screws (P 2
× 6)
SECTION 3
ELECTRICAL ADJUSTMENTS
Setting :
AF signal
generator
set
TMR-RF875R
L-CH / R-CH (J402)
Telescopic
antenna
Frequency counter
8 cm
set
TMR-RF875R
Transmission Frequency Check
1. Set the noise filter SW to OFF.
2. Input a signal of 1 kHz, 40 mVrms to only the L-CH (J402).
3. Connect a telescopic antenna to the frequency counter input
and extend the antenna to a length of approximately 8 cm.
4. Place TX-BASE board close to the frequency counter , then measure the frequencies of CH1, CH2 and CH3 and make sure the
values are as follows:
CH1 : 863.5 MHz ± 40 kHz
CH2 : 864.0 MHz ± 40 kHz
CH3 : 864.5 MHz ± 40 kHz
Pilot Signal and MPX Signal Modulation Check and
Adjustment
1. Set the channel to CH2.
2. No signal input (The operating time in this case is limited to 4
or 5 minutes.)
3. See the RV402 and RV403 to max. (clockwise)
4. Connect a digital voltmeter (AC range) to the mov able terminal
of RV403 (Fig.2).
5. Adjust the value of the digital voltmeter to minimum by R V401.
6. See the RV402 to minimum. (counter clock wise)
7. Adjust the value of the digital voltmeter to max by L407.
8. Adjust the value of the digital voltmerter to 1.7 mVrms ± 0.1
mV by RV403.
9. Connect a digital voltmeter (AC range) with LPF to movable
terminal of RV403 (Fig.2).
10. Input a signal of 1 kHz, 316 mVrms to only the L-CH.
11. Adjust the value of the digital voltmeter to 2.5 mVrms ± 0.2
mV by RV402.
Connection points and Adjustment Location :
CH3
L407
←
CH2 ←CH1
S402
RV403RV402
R464
(L-CH) (R-CH)
J402
VCO UNIT
CHG-NR board
When the frequency does not satisfy the specified value, exchange the vco unit. When completed with replacement, recheck
the frequecies of CH1, CH2 and CH3.
Compresser Output Check
1. Set the channel to CH2.
2. Input a signal of 1 kHz, 316 mVrms to L-CH and R-CH of J402.
3. Measure IC 601 pin 7 and IC 602 pin 7 on the CHG-NR board
using a digital voltmeter (AC range) and confirm the value is
100 mVrms ± 5mV (Fig.1).
4. Input a signal of 1 kHz, 31.6 mVtms to L-CH and R-CH of J402.
5. Measure IC 601 pin 7 and IC 602 pin 7 on the CHG-NR board
using a digital voltmeter (AC range) and confirm the value is
31.6 mVrms ± 5 mV (Fig.1).
6. When the frequency is not satisfied the specified value, exchange
TX- BASE board or CHG-NR board.
RV401
RV401-403,
L407
Modulation
check and
adjustment.
digital
voltmeter
(AC range)
R464
(Fig. 2)
IC 602
8
1
8
1
4
IC 601
digital
voltmeter
(AC range)
7 pin
+
–
(Fig. 1)
+
–
5
4
5
— 4 —
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