Icom Ic-r75 Communications Receiver Service Manual
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Page 11
3 - 6 The CPU has the clock function. Thus, the CPU and the clock function have the crystal separately. The CPU has the 9.8304 MHz crystal (X112) for the CPU clock, and then the oscillated 9.8304 MHz signal is applied to the IC101, pin 7 and 8. The clock function has the 32.768 kHz crystal (X111). The oscillated 32.768 kHz signal is applied to the CPU (IC101, pin 4 and 5). When the power is “OFF”, the EEPROM (IC231) is used for keep on saving the data of memory channels, and so on. 3-3-2 RESET CIRCUIT...
Page 12
![Page 12
3 - 7
3-5 PORT ALLOCATIONS
3-5-1 CPU (LOGIC UNIT; IC101)
Pin
number
1
9
11
12
14
15
16
17
18
19
21
22
23
24
25
26
36
37
38
39
40
41
42
43
44
45
46
47
48Port
name
KEY6
CRES
PWRK
DUD
DAST
RSTB
ISTB
ASTB
ECS
MCK
MDAT
PCK
PST1
PDAT
PST2
PST3
SSBK
CWK
AMK
FMK
FILK
TSK
PREK
ATTK
NRK
ANFK
NBK
AGCK
VMKDescription
Input port for [0] and [ENT] switch
from the 10-key.
Input port for the reset signal.
Low : While the reset switch is
pushed.
Input for the [POWER] switch.
Low : While [POWER] switch is
pushed.
Input...](http://img.usermanuals.tech/thumb/2452/82817/w300_icom_r75-hf-comms-reciever_manual_d-11.png "Page 12
3 - 7
3-5 PORT ALLOCATIONS
3-5-1 CPU (LOGIC UNIT; IC101)
Pin
number
1
9
11
12
14
15
16
17
18
19
21
22
23
24
25
26
36
37
38
39
40
41
42
43
44
45
46
47
48Port
name
KEY6
CRES
PWRK
DUD
DAST
RSTB
ISTB
ASTB
ECS
MCK
MDAT
PCK
PST1
PDAT
PST2
PST3
SSBK
CWK
AMK
FMK
FILK
TSK
PREK
ATTK
NRK
ANFK
NBK
AGCK
VMKDescription
Input port for [0] and [ENT] switch
from the 10-key.
Input port for the reset signal.
Low : While the reset switch is
pushed.
Input for the [POWER] switch.
Low : While [POWER] switch is
pushed.
Input...")
3 - 7 3-5 PORT ALLOCATIONS 3-5-1 CPU (LOGIC UNIT; IC101) Pin number 1 9 11 12 14 15 16 17 18 19 21 22 23 24 25 26 36 37 38 39 40 41 42 43 44 45 46 47 48Port name KEY6 CRES PWRK DUD DAST RSTB ISTB ASTB ECS MCK MDAT PCK PST1 PDAT PST2 PST3 SSBK CWK AMK FMK FILK TSK PREK ATTK NRK ANFK NBK AGCK VMKDescription Input port for [0] and [ENT] switch from the 10-key. Input port for the reset signal. Low : While the reset switch is pushed. Input for the [POWER] switch. Low : While [POWER] switch is pushed. Input...
Page 13
4 - 1 SECTION 4 ADJUSTMENT PROCEDURES 4-1 PREPARATION Ô Ô REQUIRED TEST EQUIPMENT Ô Ô CONNECTION EQUIPMENT DC power supply Frequency counter Audio generator DC Voltmeter GRADE AND RANGE Output voltage : 13.8 V DC Current capacity : 2 A or more Frequency range : 0.1–60 MHz Frequency accuracy : ±1 ppm or better Sensitivity : 100 mV or better Frequency range : 0.1–60 Hz Measuring range : 0.01–10 mV Input impedance : 50 k½/V DC or better EQUIPMENT Oscilloscope AC millivoltmeter External speaker Standard...
Page 14
4 - 2 4-2 PLL ADJUSTMENT REFERENCE FREQUENCY VCO VOLTAGE 1ST LO VOLTAGE 3RD LO VOLTAGE 3RD LO FREQUENCY BFO VOLTAGE ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITIONMEASUREMENT VALUEPOINT UNIT LOCATION UNIT ADJUST 1 2 1 2 3 4 1 1 1 1 2• Displayed frequency : 29.99999 MHz • Mode : USB • Displayed frequency : 29.99999 MHz • Mode : USB • Displayed frequency : 0.03000 MHz • Mode : USB • Displayed frequency : 60.00000 MHz • Mode : USB • Displayed frequency : 30.00000 MHz • Mode: USB • Displayed frequency :...
Page 15
4 - 3 P201BFO voltage check point P1513rd LO frequency check point P1Reference frequency check point P911st and 3rd LO voltage check point C76VCO voltage adjustment L2Reference frequency adjustment (for output frequency is 60.0000 MHz) HCP71VCO voltage check point C86 L5 Reference frequency adjustment (for output voltage is maximum)L4 • PLL UNIT
Page 16
4-3 RECEIVER ADJUSTMENTS 4 - 4 RECEIVER SENSITIVITY 1ST MIXER BALANCE ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITIONMEASUREMENT VALUEPOINT UNIT LOCATION UNIT ADJUST 1 2 1• Displayed frequency : 14.10000 MHz • Mode : USB • PREAMP1 : ON • ANT select : ANT1 • AGC : FAST • NOISE BLANKER: OFF • RF/SQL : CENTER • PBT1/PBT2 : CENTER • IF FILTER1 : 2.4 kHz • IF FILTER2 : 2.4 kHz • Connect an SSG to the antenna connector1 and set as: Frequency : 14.10150 MHz Level : 22 µV* (–13 dBµ) Modulation : OFF • Receiving •...
Page 17
RECEIVER ADJUSTMENTS (continued) 1ST IF FILTER RECEIVER TOTAL GAIN ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITIONMEASUREMENT VALUEPOINT UNIT LOCATION UNIT ADJUST 1 1 2• Displayed frequency : 14.10000 MHz • Mode : FM • PREAMP1 : ON • IF FILTER1 : 15 kHz • IF FILTER2 : 6 kHz • set an SSG as Frequency : 14.10000 MHz Level : 0.32 µV* (–10 dBµ) Deviation : ±3.5 kHz Modulation : 1 kHz • Receiving • Displayed frequency : 14.10000 MHz • Mode : USB • PREAMP1 : OFF • IF FILTER1 : 2.4 kHz • IF FILTER2 : 2.4 kHz • Set...
Page 18
4 - 6 EXT SP JACK Noise blanker check point after apply the noise signal Noise blanker adjustment before apply the noise signal R736 • MAIN UNIT CP731Noise blanker check point before apply the noise signal • Noise blanker adjustment after apply the noise signal • Pre-set to center before apply the noise signal L731 L732 RECEIVER ADJUSTMENTS (CONTINUED) NOISE BLANKER ADJUSTMENT ADJUSTMENT ADJUSTMENT CONDITIONMEASUREMENT VALUEPOINT UNIT LOCATION UNIT ADJUST 1 2• Displayed frequency : 14.10000 MHz • Mode :...
Page 19
![Page 19
4 - 7
4-4 SET MODE ADJUSTMENT
ENTERING
ADJUSTMENT
SET MODE
PBT
VOLUME
S-METER
FILTER
CALIBRATION
ADJUSTMENT ADJUSTMENT CONDITION DISPLAY OPERATION
1
1
2
3
4
1
2• Turn power OFF
• Connect a terminator to the
[REMOTE] connector on the rear
panel.
• While pushing “SET[ANT] and
“CLOCK” keys, and turn power
ON.
• Connect an SSG to the antenna
connector1 and set as:
Frequency : 14.15150 MHz
Level : 50 mV*
(–13 dBm)
Modulation : OFF
• Preset both the inner and outer
“TWIN PBT” controls to 12
o’clock position....](http://img.usermanuals.tech/thumb/2452/82817/w300_icom_r75-hf-comms-reciever_manual_d-18.png "Page 19
4 - 7
4-4 SET MODE ADJUSTMENT
ENTERING
ADJUSTMENT
SET MODE
PBT
VOLUME
S-METER
FILTER
CALIBRATION
ADJUSTMENT ADJUSTMENT CONDITION DISPLAY OPERATION
1
1
2
3
4
1
2• Turn power OFF
• Connect a terminator to the
[REMOTE] connector on the rear
panel.
• While pushing “SET[ANT] and
“CLOCK” keys, and turn power
ON.
• Connect an SSG to the antenna
connector1 and set as:
Frequency : 14.15150 MHz
Level : 50 mV*
(–13 dBm)
Modulation : OFF
• Preset both the inner and outer
“TWIN PBT” controls to 12
o’clock position....")
4 - 7 4-4 SET MODE ADJUSTMENT ENTERING ADJUSTMENT SET MODE PBT VOLUME S-METER FILTER CALIBRATION ADJUSTMENT ADJUSTMENT CONDITION DISPLAY OPERATION 1 1 2 3 4 1 2• Turn power OFF • Connect a terminator to the [REMOTE] connector on the rear panel. • While pushing “SET[ANT] and “CLOCK” keys, and turn power ON. • Connect an SSG to the antenna connector1 and set as: Frequency : 14.15150 MHz Level : 50 mV* (–13 dBm) Modulation : OFF • Preset both the inner and outer “TWIN PBT” controls to 12 o’clock position....
Page 20
S.=Surface mount R131 7210003040 VARIABLE TP96D26-22F-10KBX2-2240 R141 7210003030 VARIABLE TP96D00-22F-10KBX2-2240 R143 7030003540 S.RESISTOR ERJ3GEYJ 682 V (6.8 k½) J101 6510020710 S.CONNECTOR 52793-1090 EP1 0910051172 PCB B 5271B L121 6200003950 S.COIL HF50ACC 322513-T R121 7030006070 S.RESISTOR ERJ12YJ101H (100 ½) R122 7030006070 S.RESISTOR ERJ12YJ101H (100 ½) C121 4030006880 S.CERAMIC C1608 JB 1H 472K-T-A C122 4030006880 S.CERAMIC C1608 JB 1H 472K-T-A C123 4030006880 S.CERAMIC C1608 JB 1H...