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This service manual describes the latest service information for connect the transceiver to an AC outlet or to a DC the IC-2800H FM TRANSCEIVER at the time of publication. power supply that uses more than 16 V. Such a connection could cause a fire hazard and/or electric shock.
SECTION 2 INSIDE VIEWS • CONTROL UNIT * : Located underside of this point SUB CPU (IC10: HD6433032SK) CFL drive (Q14, Q15, Q19*, Q20*) CPU reset IC* (IC11: S-80945ANMP-DD9) LCD controller (IC8: SED1354F0A) R-data buffer amplifier* (Q13: 2SA1576) T-data buffer amplifier* (Q12: 2SC4081) •...
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SECTION 3 DISASSEMBLY INSTRUCTIONS • Removing the MAIN unit • Removing the CONTROL unit q Unscrew 1 screw, q Unscrew 4 screws, , and remove the cover. , and remove the cover. w Unplug J4 to separate the fan motor from the MAIN unit. w Unplug J5 to separate the speaker and front panel.
SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS The tunable bandpass filters (D11–D13, D15) employ varac- tor diodes to tune the center frequency of the RF passband 4-1-1 DUPLEXER CIRCUIT for wide bandwidth receiving and good image response The transceiver has a duplexer (low-pass and high-pass fil- rejection.
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The 1st IF signal from the 2nd IF amplifier is applied to the 4-1-9 VHF SQUELCH CIRCUIT 2nd mixer section of IC28 (pin 16), and is mixed with a 15.2 • NOISE SQUELCH MHz 2nd LO signal generated by the reference oscillator cir- A noise squelch circuit cuts out AF signals when no RF sig- cuit (X1, IC2) to produce a 450 kHz VHF 2nd IF signal.
4-1-10 UHF RF CIRCUIT 4-2 TRANSMITTER CIRCUITS The UHF RF signals are passed through part of a duplexer 4-2-1 MICROPHONE AMPLIFIER CIRCUIT (high-pass filter; L44, L45, L82, C189, C190, C493). The sig- The microphone amplifier circuit amplifies audio signals from nals are then passed through the low-pass filter (L42, L43, the microphone to a level needed at the modulation circuit.
4-2-5 VHF APC CIRCUIT 4-2-9 UHF APC CIRCUIT The APC circuit protects the power amplifier from a mis- The APC detector circuit (D25 and D26) detects forward sig- matched output load and stabilizes transmit output power. nals and refrection signals respectively. The combined volt- age is at a minimum level when the antenna is matched at 50 Ω...
4-3-3 UHF LOOP 4-4 POWER SUPPLY CIRCUITS The generated signal at the U-VCO (Q20, Q21, D20, D21) • VOLTAGE LINE enters the PLL IC (IC2, pin 15) via buffer-amplifiers (Q22, Line Description Q23) and is divided at the programmable divider section and is then applied to the phase detector section.
4-5 PORT ALLOCATIONS 4-5-1 CPU (MAIN UNIT; IC19) Port Port Description Description number name number name Input port for the decoded CTCSS sig- Outputs transmit signal for VHF band. TONEIN nals. High : While transmitting on VHF band. OSC1, Input ports for the CPU system clock 7, 8 OSC2 oscillator (X4: 10.000 MHz).
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SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION All adjustments in this section must be performed on wide bandwidth condition unless specified otherwise. (Narrow bandwidth is selectable for Europe and Italy vertions only.) ‘ ‘ REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE Output voltage...
5-2 PLL AND TRANSMITTER ADJUSTMENTS ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST PLL LOCK • VHF displayed freq. : MAIN Connect a digital 1.65 V MAIN VOLTAGE 145.000 MHz multi-meter or oscil- • Receiving loscope check point CP-LV. •...
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DC power supply 13.8 V / 20 A R119 R119 UHF output power VHF output power adjustment adjustment CP-LV PLL lock voltage check point Reference frequency adjustment PLL lock voltage adjustment VHF deviation adjustment UHF deviation adjustment Controller 5 - 3...
5-3 RECEIVER ADJUSTMENTS The receiver adjustments must be performed after PLL ADJUSTMENTS. ADJUSTMENT ADJUSTMENT CONDITION OPERATION • Turn into sensitivity setting mode. • Connect a JIG1 to the [MIC] connector, then turn SENSITIVITY power ON. • Select an adjustment channel by pushing 1st or 2nd •...
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RECEIVER ADJUSTMENTS (continued) ADJUSTMENT MEASUREMENT POINT ADJUSTMENT ADJUSTMENT CONDITION VALUE UNIT LOCATION UNIT ADJUST SQUELCH • UHF displayed freq. : Speaker At the point where the MAIN R229 (UHF) 445.000 MHz [USA] signal just appears. 435.000 MHz other • Set the squelch level to 22 % using the HM-98 microphone.
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SECTION 6 PARTS LIST [CONTROL UNIT] [CONTROL UNIT] ORDER ORDER DESCRIPTION DESCRIPTION 1130009250 S.IC MN83951 7030003520 S.RESISTOR ERJ3GEYJ 472 V (4.7 kΩ) 1130008560 S.IC TC75S51F (TE85L) 7030003520 S.RESISTOR ERJ3GEYJ 472 V (4.7 kΩ) ERJ3GEYJ 101 V (100 Ω) 1180001830 S.IC M5291FP 7030003320 S.RESISTOR ERJ3GEYJ 101 V (100 Ω)
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[CONTROL UNIT] [CONTROL UNIT] ORDER ORDER DESCRIPTION DESCRIPTION R127 7030003440 S.RESISTOR ERJ3GEYJ 102 V (1 kΩ) R240 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ) ERJ3GEYJ 471 V (470 Ω) R128 7030003400 S.RESISTOR R241 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ) R129 7030003560 S.RESISTOR ERJ3GEYJ 103 V (10 kΩ)
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SECTION SECTION 8 PARTS LIST SEMI-CONDUCTOR INFORMATION 8 - 1 TRANSISTORS 8 - 2 DIODES NAME SYMBOL INSIDE VIEW NAME SYMBOL INSIDE VIEW NAME SYMBOL INSIDE VIEW NAME SYMBOL INSIDE VIEW 1SS355 2SA1362-GR DA114 2SJ144-GR MA728 2SA1576A R 2SB1201-S DA115 1SS254 yellow 3SK166A-2-T7...
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SECTION 9 BOARD LAYOUTS 9 - 1 CONTROL UNIT • TOP VIEW The combination of this page and the next page shows the unit layout in the same configuration as the actual from CFL BACK LIGHT P.C. Board. MP24 UVOL VVOL CFL+ NC NC CFL–...
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CONTROL UNIT • BOTTOM VIEW The combination of this page and the previous page from SPEAKER (SP1) shows the unit layout in the same configuration as the actual P.C. Board. VVOL R145 R151 UVOL R151 R145 from CFL BACK LIGHT (DS2) EXT.
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HV IN CLONE I/O EXT SP ANTENNA MAIN UNIT • TOP VIEW The combination of this page and the next page shows the unit layout in the same configuration as the actual P.C. Board. from FAN MOTOR FV 1 to OPTIONAL UNIT AFOUT PSQL MDATA E MIC MICE PTT EXTMIC MU/D M8V...
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from EXT SP CLONE I/O MAIN UNIT • BOTTOM VIEW The combination of this page and the previous page shows the unit layout in the same configuration as the actual P.C. Board. AFOUT PSQL M8V MU/D EXTMIC PTT MICE MIC E MDATA RDATA TDATA PTTP...
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INPUT POWER DC 13.8 V SECTION 10 BLOCK DIAGRAM — POWER SW CTRL 8V REG Q74 DTC143XU IC14 TA7808F Q75 2SB1201 FAN CONTROL 13.8V 2SC4081 2SB1132 MA8075 MF1 (CHASSIS) VR8V VT8V —15V 13.8V BACK LIGHT +5VA V BIAS SEL VT8V REG DC-DC Q34 UMG9N 1/2 Q9 2SC4081...
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