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1、HF/50MHz ALL MODE TRANSCEIVER i756PRO SERVICE MANUAL VERSION U.S.A. Europe France Italy Korea Spain SYMBOL USA EUR FRA ITR KOR ESP INTRODUCTION This service manual describes the latest service information for the IC-756PROII HF/50MHz ALL MODE TRANSCEIVER. DANGER NEVER connect the transceiver to an A
2、C outlet or to a DC power supply that uses more than 16 V. This will ruin the transceiver. DO NOT expose the transceiver to rain, snow or any liquids. DO NOT reverse the polarities of the power supply when connecting the transceiver. DO NOT apply an RF signal of more than 20 dBm (100 mW) to the ante
3、nna connector. This could damage the transceiv- ers front end. ORDERING PARTS Be sure to include the following four points when ordering replacement parts: 1. 10-digit order numbers 2. Component part number and name 3. Equipment model name and unit name 4. Quantity required 1110000960S.ICNJM4558MIC-
4、756PROII MAIN-A UNIT 5 pieces 8810005770 Screw BiH M38 ZK IC-756PROII Top cover10 pieces Addresses are provided on the inside back cover for your convenience. REPAIR NOTES 1. Make sure a problem is internal before disassembling the transceiver. 2. DO NOT open the transceiver until the transceiver is
5、 disconnected from its power source. 3. DO NOT force any of the variable components. Turn them slowly and smoothly. 4. DO NOT short any circuits or electronic parts. An insu- lated tuning tool MUST be used for all adjustments. 5. DO NOT keep power ON for a long time when the trans- ceiver is defecti
6、ve. 6. DO NOT transmit power into a signal generator or a sweep generator. 7. ALWAYS connect a 50 dB to 60 dB attenuator between the transceiver and a deviation meter or spectrum ana- lyzer when using such test equipment. 8. READ the instructions of test equipment thoroughly before connecting equipm
7、ent to the transceiver. VER. NO. #22 #23 #24 #28 #29 #30 To upgrade quality, any electrical or mechanical parts and internal circuits are subject to change without notice or obligation. TABLE OF CONTENTS SECTION 1SPECIFICATIONS SECTION 2INSIDE VIEWS SECTION 3CIRCUIT DESCRIPTION 3 - 1RECEIVER CIRCUIT
8、S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1 3 - 2TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 - 4 3 - 3PLL CIRCUITS . . . . . . .
9、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 6 3 - 4ANTENNA TUNER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 8 3 - 5SCOPE CIRCUIT . . . . . . . . .
10、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 9 3 - 6POWER SUPPLY CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 9 3 - 7LOGIC CIRCUITS . . . . . . . . . . . . .
11、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 10 SECTION 4ADJUSTMENT PROCEDURES 4 - 1PREPARATION BEFORE SERVICING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 1 4 - 2PLL ADJUSTMENT . . . . .
12、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2 4 - 3TRANSMITTER ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 4 4 - 4RECEIVER ADJUSTMENT . . . . . . . . .
13、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 8 4 - 5TUNER ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 12 4 - 6METER ADJUSTMENT . . . . . . . . . . . . . . . . .
14、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 13 SECTION 5PARTS LIST SECTION 6MECHANICAL PARTS SECTION 7SEMI-CONDUCTOR INFORMATION SECTION 8BOARD LAYOUTS 8 - 1PBT, RIT AND MIC BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、. . . . . . . . . . . . . . . . 8 - 1 8 - 2DISPLAY BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 2 8 - 3MODE, PHONE, KEY AND TEN-KEY BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、. . . . . 8 - 4 8 - 4RF-A UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 6 8 - 5PLL UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . . . . . . . . . 8 - 8 8 - 6MAIN-A UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 10 8 - 7DSP-A, MEMORY AND BPF BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . 8 - 12 8 - 8PA UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 14 8 - 9FILTER UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、 . . . . . . . . . . . 8 - 16 8 - 10 TUNER BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 18 8 - 11 CTRL UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . 8 - 20 SECTION 9BLOCK DIAGRAM SECTION 10VOLTAGE DIAGRAMS 10 - 1 FRONT UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 1 10 - 2 DSP-A BOARD . . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 2 10 - 3 TUNER, MEMORY BOARDS AND CTRL UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 3 10 - 4 MAIN-A UNIT (1) . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 4 10 - 5 MAIN-A UNIT (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5 10 - 6 PLL UNIT . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 6 10 - 7 PAAND FILTER UNITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 7 10 - 8 RF-A UNIT AND BPF BOARD . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 8 SECTION 1SPECIFICATIONS 1 - 1 I GENERAL Frequency coverage: Receive0.03060.000 MHz*1, *2 Transmit1.8001.999 MHz*23.5003.999 MHz*2 7.0007.300 MHz*210.10010.150 MHz*2 14.00014.350 MHz*218.06818.168 MHz*2 21.00021.450
25、 MHz*224.89024.990 MHz*2 28.00029.700 MHz*250.00054.000 MHz*2 *1Some frequency bands are not guaranteed. *2Depending on version. Mode: USB, LSB, CW, RTTY, AM, FM Number of memory channels : 101 (99 regular, 2 scan edges) Antenna connector : SO-239 2 and phono (RCA); 50 Usable temp. range: 10C to +50
26、C (14F to 122F) Frequency stability : Less than 0.5 ppm from 1 min. after power ON. Freq. resolution: 1 Hz Power supply: 13.8 V DC 15 % (negative ground) requirement Current consumption: Transmitmax. power23 A Receivestand-by3.0 A (typical) max. audio3.3 A (typical) Dimensions: 340 (W) 111(H) 285(D)
27、 mm 1338(W) 438(H) 11732(D) in Weight: 9.6 kg (21 lb 1 oz) ACC 1 connector: 8-pin DIN connector ACC 2 connector: 7-pin DIN connector CI-V connector: 2-conductor 3.5(d) mm (18) Display: 5-inch (diagonal) TFT color LCD I TRANSMITTER Output power: SSB/CW/RTTY/FM5100 W AM540 W Modulation system : SSBPSN
28、 modulation AMLow power modulation FMPhase modulation Spurious emission : Less than 50 dB (HF bands) Less than 60 dB (50 MHz band) Carrier suppression: More than 40 dB Unwanted sideband suppression: More than 55 dB TX variable range : 9.999 kHz Mic. connector: 8-pin connector (600 ) ELE-KEY connecto
29、r: 3-conductor 6.35(d) mm (14) KEY connector: 3-conductor 6.35(d) mm (14) SEND connector: Phono (RCA) ALC connector: Phono (RCA) I RECEIVER Receive system: Triple-conversion superheterodyne Intermediate frequencies: 1st IF frequency64.455 MHz 2nd IF frequency455 kHz 3rd IF frequency36 kHz Sensitivit
30、y: SSB, CW, RTTY (at 2.4 kHz bandwidth) 1.829.99 MHz*10.16 V (10 dB S/N) 50.054.0 MHz*20.13 V (10 dB S/N) AM (at 6.0 kHz bandwidth) 0.51.799 MHz13 V (10 dB S/N) 1.829.99 MHz*12.0 V (10 dB S/N) 50.054.0 MHz*21.0 V (10 dB S/N) FM (at 15 kHz bandwidth) 28.029.99 MHz*10.5 V (12 dB SINAD) 50.054.0 MHz*20
31、.32 V (12 dB SINAD) *1Pre-amp 1 ON *2Pre-amp 2 ON Squelch sensitivity : (Pre-amp OFF) SSB/CW/RTTYLess than 5.6 V FMLess than 1.0 V Selectivity: SSB/RTTY (at 2.4 kHz bandwidth) More than 2.4 kHz/6 dB Less than 3.6 kHz/60 dB CW (at 500 Hz bandwidth) More than 500 Hz/6 dB Less than 700 Hz/60 dB AM (at
32、6 kHz bandwidth) More than 6.0 kHz/6 dB Less than 15.0 kHz/60 dB FM (at 15 kHz bandwidth) More than 12 kHz/6 dB Less than 20 kHz/60 dB Spurious and image: More than 70 dB rejection ratio(except IF through in 50 MHz band) RIT variable range : 9.999 kHz Audio output power: More than 2.0 W at 10 % dist
33、ortion (at 13.8 V DC)with an 8 load PHONES connector: 3-conductor 6.35 (d) mm (14) EXT SP connector : 2-conductor 3.5 (d) mm (18) 8 I ANTENNA TUNER Matching impedance range: HF bands16.7 to 150 unbalanced*1 50 MHz band20 to 125 unbalanced*2 *1Less than VSWR 3:1; *2Less than VSWR 2.5:1 Minimum operat
34、ing input power: HF bands: 8 W 50 MHz band: 15 W Tuning accuracy: VSWR 1.5:1 or less Insertion loss: Less than 1.0 dB (after tuning) All stated specifications are subject to change without notice or obligation. 2 - 1 FILTER unit Current transformer (L1: LR-364) C-MOS IC (IC14: TC74AC04F) FAN TUNER u
35、nit Fan control circuit Antenna tuner CPU (IC5: M38022M2-138FP) CTRL unit Common filter (L501, L502: LR-386) PA unit Drive amplifier TOP VIEW SECTION 2INSIDE VIEWS 2 - 2 BOTTOM VIEW VCO-B circuit YGR amplifier (IC151: PC1678G) BPF board Pre amplifier (IC451: PC1658G) FM IF IC (IC841: TA31136FN) RF-A
36、 unit Optional unit UT-102 2nd IF filter (FI111: CFK455E10) 3rd mixer (IC151: TC4W53FU) MAIN-A unit PLL unit MEMORY board DSP-A board VCO-A circuit Ceramic filter (FI842: CFJ455K8) SECTION 3CIRCUIT DESCRIPTION 3 - 1 3-1 RECEIVER CIRCUITS 3-1-1 RF SWITCHING CIRCUIT (CTRL AND RF-A UNITS) The RF switch
37、ing circuit leads receive signals to bandpass filters from an antenna connector while receiving. However, the circuit leads the signal from the RF power amplifier to the antenna connector while transmitting. RF signals from ANT 1 or ANT 2 pass through the anten- na selector (RL3), transmit/receive s
38、witching relays (RL1, RL2, RL4), and low-pass filter (L27, L28, C63C66, C105), and are then applied to the RF-A unit via J2. The signals from the CTRL unit either bypass or pass through the 6 dB (RF-A unit, RL121, R121) and/or 12 dB (RF-A unit, RL122, R123) attenuators via the antenna selec- tor (RL
39、101). By selecting the attenuators, 0 (bypass), 6, 12 and 18 dB attenuations are obtained. The signals are then applied to the RF filters. When the RX ANT is selected, the RF signals are passed through the low-pass filter (RF-A unit, L112, L111, C111C116), then applied to the antenna selector (RF-A
40、unit, RL101). 3-1-2 RF BANDPASS FILTER CIRCUIT (RF-A UNIT AND BPF BOARD) RF bandpass filters pass only the desired band signals and suppress any undesired band signals. The RF circuit has 11 bandpass filters and 1 low-pass filter. (1) 0.031.6 MHz (BPF BOARD) The signals pass through the low-pass fil
41、ter (L181L183, C181C185), attenuator (R181R183), and are then applied to the RF amplifiers (Q501, Q601). (2) 1.660 MHz (RF-A UNIT AND BPF BOARD) The signals pass through the high-pass filter (L171L174, C171C174) to suppress excessively strong signals below 1.6 MHz. The filtered signals are applied t
42、o one of 11 band- pass filters on the table at right above, and then applied to or bypassed the pre-amplifier circuit. 3-1-3 PRE-AMPLIFIER CIRCUITS (RF-A UNIT) The IC-756PROhas 2 gain levels of pre-amplifier circuits. One has 10 dB gain for the 1.821 MHz bands and the other one has 16 dB gain for th
43、e upper 24 MHz bands. When the P.AMP switch is set to P.AMP 1 or P.AMP 2, the signals are applied to the pre-amplifier 1 (Q441, Q442) or pre-amplifier 2 (IC451) circuit, respectively. Pre-amplified or bypassed signals are applied to the RF amplifier circuits (Q501, Q502 and Q601, Q602). 3-1-4 RF AMP
44、LIFIER AND 1ST MIXER CIRCUITS (RF-A UNIT) The 1st mixer circuit mixes the receive signals with the 1st LO signal to convert the receive signal frequencies into a 64.455 MHz 1st IF signal. The IC-756PROhas two 1st mixer circuits for the dualwatch function. The signals from the pre-amplifier circuit,
45、or signals which bypass the pre-amplifiers, are divided at L491. Each signal is applied to a 60 MHz cut-off low-pass filter, RF amplifier (Q501, Q502 and Q601, Q602) and then to a 1st mixer (Q511Q514 or Q611Q614). Each 1st LO signal (64.4850124.4550 MHz) enters the RF -A unit from the PLL unit via J
46、561 or J661. The LO signals are amplified at the LO amplifier (Q561 or Q661), filtered by a low-pass filter, and then applied to each 1st mixer. Used RF filter * : On the BPF board Receiver construction LPF or BPF 1st LO B 1st LO A 2nd LO 64.0 MHz Crystal filter FI711a/b 1st mixer A Q511Q514 1st mix
47、er B Q611Q614 2nd mixer Q941Q944 3rd LO 491 kHz 3rd mixer IC151 64.455 MHz 0.0360.0 MHz Ceramic filter FI132, FI111 455 kHz to squelch gate (IC301) 36 kHzDSP-A board RF-A UNITMAIN-A UNIT Band 0.031.6 MHz 1.62 MHz 23 MHz 34 MHz 46 MHz 68 MHz 811 MHz Band 1115 MHz 1522 MHz 2230 MHz 3050 MHz 5054 MHz 5
48、460 MHz Control signal B7 B8 B9 B10W B10 B10W Control signal B0 B1 B2 B3 B4 B5 B6 Input diode N/A *D2001 *D2021 *D2041 *D2061 *D2081 D261 Input diode D281 D301 D321 D341 D361 D341 3 - 2 3-1-5 1ST IF CIRCUIT (RF-A UNIT) The 1st IF circuit filters and amplifies the 1st IF signal. The 1st IF signal com
49、bined at L653 is applied to a pair of MCF (Monolithic Crystal Filter; FI711a/b) to suppress out-of-band signals. The level of converted 1st IF signal is adjusted at the PIN attenuators (D531D533, D535 or D631D633, D635) con- trolled by the BAL controller for the dualwatch function. The signal is applied to the 1st IF amplifier (Q551 or Q651) and then combined at L653. The combined signal passes through the 3 dB attenuator (R711R713) and MCFs (FI711a/b). The signal is amplified at the 1st IF amplifier (Q721). The amplified signal is th
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