Specification ………………………………………………………………………………………………………2-5
Block Diagram ………………………………………………………………………………………………………6
Alignment Instructions…………………………………………………………………………….………………7-11
Test Points Disgram…………………………………………………………………………….……….……………12
Main PCB Top View…………………………………………………………………………….……….……………13
Main PCB Bottom View.………………………………………………………………………….……..………..…..14
LCD PCB Top View……………………………………………………………………………….………….……15
LCD PCB Bottom View……………………………………………………………………………………………16
PCB Top View…………………………………………………………………………….……….……………17
PCB Bottom View…………………………………………………………………………….……….……………18
Wiring Diagram..….………………………………………….………………….….……………..……….19
Troubleshooting Flow Chart..….………………………………………….……………….….……………..……20-21
Electrical Parts List………………………………………………………………………………....……………22-25
Mechanical Parts List……………………………………………………………………….……….…………….26-27
Exploded Views.…………………………………………………………………………….…………….……………28
IC Circuit Block Diagram…………………………………………..…………….………………………………29-38
IC and Transistor Voltage Chart….……………………………..…………………………….…………………39-43
Semiconductor Lead Identifications……………………………………………………………………..……..…44
MAIN Schematic Diagram……………………………………………………………………………………………45
Image Rejection S/N=6dB 1404KHz36 30 dB
I.F. Rejection S/N=6dB 603KHz50 40 dB
Selectivity(±10KHz)
S/N=6dB 32 26 dB
Bandwidth(-6dB) S/N=6dB 6-11 KHz
T. H. D. 74dBu/m2 4 %
Lowest Batt. Volt. 74dBu/m6.3 6.7 V
Hum Modulation
Auto. Scan. Stop. Sens. 56 62
100dBu/m
dB
dBu/m
Current Consumption 74dBu/m160 180 mA
999KHz
Tone Action (3KHz) 74dBu/mdB
Freq. Response
(-6dB)
74dBu/m
100 200 Hz
25001800 Hz
Output Power 80% Mod. 10%T.H.D.1000700 mW
Over load capacity 80%mod. 10%T. H.D.100 90
(1) Press the power button to turn on the radio.
(2) Connect the input terminal of AM IF sweep generator in series with a resistor of 1.2KΩ
to the TP1 and TP2.
AM T1
c. Instrument Connection
(3) Connect the RF output terminal of AM IF sweep generator to another test point TP5.
(4) Connect a 100μF electrolytic capacitor to test point TP2 and TP4.
(5) Adjust T1 to have a max. output with a marker frequency of 450 kHz on the sweep
scope.
T1
TP4TP2
100uF
450KHz Marker
TP1
IN
TP2
1.2KΩ
RF
OUT
2.2KΩ
AM IF Sweep Generator
TP5
7
Page 8
2. ALIGNMENT FOR AM/LW TUNING VOLTAGE RANGE
a. Required Instruments:
DVM
b. Alignment Procedure
Mode Adjustment Procedure
(1) Turn on the radio.
L3
AM
c. Instrument Connection
TC1
(2) Connect the probe of DVM to the test point TP1 and TP2.
(3) Tune the AM frequency to 522 kHz.
(4) Adjust L3 to have a reading of 1.2 ±0.04V.
(5) Tune the AM frequency to 1629 kHz.
(6) Adjust TC1 to have a reading of 7.6 ±0.3V.
TC1
L3
DVM
TP1
TP2
8
Page 9
3. ALIGNMENT FOR FM TUNING VOLTAGE
a. Required Instruments
DVM
b. Alignment Procedure
Mode Adjustment Procedure
(1) Turn on the radio.
FM L4
c. Instrument Connection
(2) Connect the probe of DVM to the TP1 and TP2
(3) Tune the FM frequency to 108MHz.
(4) Adjust L4 to have a reading of 8.2V ±0.3V.
L4
TP1
TP2
DVM
9
Page 10
4. ALIGNMENT FOR AM/LW SENSITIVITY
a. Required Instruments
AM Signal Generator
SSVM
b. Alignment Procedure
Mode Adjustment Procedure
(1) Turn on the radio.
(2) Connect a SSVM to the speaker TP7 and TP8 terminals.
(3) Connect an AM signal generator together with standard loop dummy antenna and
feed 30% modulated signal to the AM ferrite bar antenna L12.
TC3
AM
L12
c. Instrument Connection
(4) Tune the generator frequency to 1404 kHz.
(5) Tune the AM frequency to 1404 kHz and adjust TC3 to have a max reading on
SSVM.
(6) Return the generator frequency to 603 kHz.
(7) Tune the AM frequency to 603 kHz and adjust L12 to have a max reading on
SSVM.
(8) Repeat (4) to (7) as necessary to minimize tracking error.
AM Signal Generator
Loop Antenna
60 cm
The radio is located
perpendicularly to
the Loop Antenna
TC3
L12
DVM
TP7
TP8
10
Page 11
5. ALIGNMENT FOR FM TUNING SENSITIVITY
a. Required Instruments
FM Signal Generator (frequency range up to 220 MHz)
SSVM
b. Alignment Procedure
Mode Adjustment Procedure
(1) Turn on radio.
(2) Connect a SSVM to speaker TP7 and TP8.
(3) Connect a FM signal generator to TP10 and TP11.
TC2
FM
c. Instrument Connection
L8
(4) Set the signal generator to 22.5 kHz deviation with 1 kHz modulation.
(5) Always tune the generator frequency to exactly same as the radio band frequency
before adjustment.
(6) Tune the FM frequency to 106MHz and adjust TC2 to have a max audio output.
(7) Tune the FM frequency to 90MHz and adjust L8 to have a max audio output.
(8) Repeat (6) to (7) as necessary to minimize tracking error.
TC2
L8
DVM
TP11
SSG
TP10
11
TP7
TP8
Page 12
TEST POINTS DIAGRAM
12
Page 13
MAIN PCB TOP VIEW
13
Page 14
MAIN PCB BOTTOM VIEW
14
Page 15
LCD PCB TOP VIEW
15
Page 16
LCD PCB BOTTOM VIEW
16
Page 17
PCB TOP VIEW
17
Page 18
PCB BOTTOM VIEW
18
Page 19
WIRING DIAGRAM
19
Page 20
TROUBLESHOOTING FLOW CHART
( 1 ) DAB can not be turned on
Check whether the pin 18 of DAB
MODULE
exceeds 3.3V DC.
Yes
Check whether the pin1 of DAB
MODULE exceeds 5V DC.
No Check the IC10 and Q14 circuit is
normal.
Then replace the abnormal parts.
No Check the IC13 and Q25 circuit is
normal.
Then replace the abnormal parts.
( 2 ) Weak sensitivity in DAB band
Check the C134, C135, L10, L11
circuit is normal.
Yes
Check the ANT circuit is normal.
No
Check the HPF circuit.
Then replace the abnormal parts.
20
Page 21
( 3 ) Weak sensitivity in FM
Check whether the sensitivity is Yes Check the antenna wire and BPF
recovered if antenna is directly circuit.
connected to the pin 2 of IC12.
Yes
Check whether the IF waveform is
normal.
Yes
Check whether the tuning voltage
is normal.
Then replace the abnormal parts.
No
No
Check the IC12 circuit.
Then replace the abnormal parts.
Check the L4 local oscillator circuit.
Then replace the abnormal parts.
Check whether L8 and TC2 the No
corresponding RF tank circuit are Then replace the abnormal parts.
normal.
Yes
( 4 ) PLL does not work
Check whether the C53 exceeds
15V DC.
Yes
Check whether the circuit of LPF
is normal.
No
No
Check the DC-DC converter circuit.
Then replace the abnormal parts.
Check Q2 and Q3.
Then replace the abnormal parts.
Yes
Check whether the local oscillator
circuit is normal.
Yes
21
Check C121 and D11.
Then replace the abnormal parts.
Page 22
DPR-25
Y
K
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