Icom IC-775 User manual

o
ICOM
SERVICE
MANUAL
Icbm Inc.

INTRODUCTION DANGER
This service manual describes the latest service information for
the IC-775/DSP HF ALL BAND TRANSCEIVER at the time of
publication.
5versions of the IC-775DSP and 5versions of the IC-775 have
been designed. This service manual covers each version.
MODEL VERSION NO. VERSION SYMBOL
IC-775DSP
#02 Other OTH
#03 Spain ESP
#04 France FRA
#05 Germany FRG
#07 Europe EUR
IC-775
#12 Other OTH-1
#13 Spain ESP-1
#14 France FRA-1
#15 Germany FRG-1
#17 Europe EUR-1
To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.
Use ONLY the specified AC voltage described on the AC
power socket. Other voltage may cause the transceiver
damage or personal injury.
DO NOT touch the REG unit after the transceiver is connected
to an AC outlet. An insulated tool must be used at all time.
DO NOT expose the transceiver to rain, snow or any liquids.
DO NOT apply an RF signal of more than 20 dBm (100 mW)
to the antenna connector. This could damage the
transceiver's front end.
Danger of explosion if alithium battery is incorrectly replaced.
Replace only with the same or equivalent type recommended
by the battery manufacturer.
Dispose of used batteries according to the manufacturer's
instructions.
Explosionsqefahr bei unsachgemaBen Austaush der Batterie.
Ersatz nur durch denselben oder einen vom Hersteller
empfohlenen ahniichen Typ. Entsorgung gebrauchter
Batterein mach Angaben des Herstellers.
ORDERING PARTS REPAIR NOTES
Be sure to include the following four points when ordering 1
.
replacement parts:
2
1.10-diglt order numbers
2. Component part number and name ^
3. Equipment model name and unit name
4. Quantity required ^
<SAMPLE ORDER>
1110003140 S.IC NJM4558M(T1) IC-775 MAIN UNIT Spieces 5.
8810004620 Screw PHM4x8ZK IC-775 Topcover 10 pieces
Addresses are provided on the inside back cover for your 6.
convenience.
7.
8.
Make sure aproblem is internal before disassembling the
transceiver.
DO NOT open the transceiver until the transceiver is
disconnected from its power source.
DO NOT force any of the variable components. Turn them
slowly and smoothly.
DO NOT short any circuits or electronic parts. An insulated
tuning tool MUST be used for all adjustments.
DO NOT keep power ON for along time when the
transceiver is defective.
DO NOT transmit power into asignal generator or asweep
generator.
ALWAYS connect a50 dB to 60 dB attenuator between
the transceiver and adeviation meter or spectrum analyzer
when using such test equipment.
READ the instructions of test equipment thoroughly before
connecting equipment to the transceiver.

TABLE OF CONTENTS
SECTION 1SPECIFICATIONS 1-1
SECTION 2DISASSEMBLY AND OPTION INSTALLATIONS 2-1to 5
2-1DISASSEMBLY INSTRUCTIONS 2-
1
2-2OPTION INSTALLATIONS 2-2
SECTION 3INSIDE VIEWS 3-1 to 2
SECTION 4CIRCUIT DESCRIPTION 4-1to 13
4-1 RECEIVER CIRCUITS 4-1
4-2TRANSMITTER CIRCUITS 4-5
4-3 PLL CIRCUITS 4-8
4-4ANTENNA TUNER CIRCUITS 4-9
4-5 LOGIC CIRCUITS 4-11
4-
6DSP CIRCUITS 4-13
SECTION 5ADJUSTMENT PROCEDURES 5-1 to 14
5-
1
PREPARATION BEFORE SERVICING 5-
1
5-
2PLL ADJUSTMENT 5-2
5-3 RECEIVER ADJUSTMENT 5-4
5-4TRANSMITTER ADJUSTMENT 5-8
5-5TUNER UNIT ADJUSTMENT 5-14
SECTION 6PARTS LIST 6-1to 35
SECTION 7MECHANICAL PARTS 7-1to 7
SECTION 8SEMI-CONDUCTOR INFORMATION 8-
1
SECTION 9BOARD LAYOUTS 9-1to 13
9-1DSP UNIT (IC-775DSP only) 9-
1
9-2SW-A UNIT 9-2
9-3SW-B AND DISPLAY UNITS 9-4
9-4 VR-AUNIT 9-5
9-5 MAIN UNIT 9-6
9-6 RFUNIT 9-7
9-7 IF UNIT 9-8
9-8 PLL UNIT 9-9
9-9 PA UNIT 9-10
9-10 FILTER UNIT 9-11
9-11 CTRL UNIT 9-12
9-12 RELAY UNIT 9-13
SECTION 10 VOLTAGE DIAGRAM /BLOCK DIAGRAM 10-1 to 6

SECTION 1SPECIFICATIONS
GENERAL
•Frequency coverage:
Receive 100 kHz -29.990 MHz
Transmit 1.800- 1.999999 MHz*'
3.500- 3.999999 MHz*'
7.000-
7.300 MHz*'
10.100 -10.150 MHz
14.000
-
14.350 MHz
18.068 -18.168 MHz
21.000-
21.450 MHz
24.890 -24.990 MHz
28.000 -29.700 MHz
*' 1.830-1 .850 for Spain version;
1.81 0-1 .850 for France version;
1.81 5-1 .835/1 .850-1 .890 for
Germany version
*' 3.500-3.800 for Spain, France and
Germany versions
*'7.000-7.100 for Spain, France and
Germany versions
•Mode :SSB, CW, RTTY, AM, FM
•Number of memory :101 (99 regular, 2scan edges)
channels
•Antenna impedance :50 Qnominal
•Usable temperature :-10°C to +60°C
;
range +14°F to +140T
•Frequency stability :Less than ±200 Hz from 1min, to
60 min, after power ON.
After that, rate of stability change is less
than ±30 Hz/hr. at +25t!: +77T.
Temperature fluctuations (OTD to
+50X:; +32T to +122 ”F) less than
±350 Hz.
•Power supply requirement:
120Vtype 100-120VAC
230 Vtype 220 -240 VAC
•Power consumption :
Transmit max. power 760 VA
Receive squelched 140VA
max. audio output 150 VA
•Dimensions :424(W) x150(H) x390(D) mm
1611/16(W) x5M/32(H) X1511/32(0)'
(projections not included)
•Weight :16.5 kg; 36.4 lb (without DSP unit)
16.7 kg; 36.8 lb (with DSP unit)
TRANSMITTER
•Output power :SSB, CW, RTTY, FM 5-200 W
AM 5-50 W
(continuously adjustable)
•Spurious emissions :Less than -60 dB
•Carrier suppression :More than 40 dB
•Unwanted sideband :More than 55 dB
•Microphone :600 Q
impedance
RECEIVER
•Receive system
SSB, CW, RTTY, Quadruple-conversion
AM superheterodyne
FM Triple-conversion superheterodyne
•Intermediate frequencies: (Unit: MHz)
MODE SSB CW, RTTY AM FM
1st 69.0100
2nd 9.0115 9.0106 9.0100
3rd 0.455 0.455 0.455 0.455
4th 10.6950 10.6950 10.6950 -
•Sensitivity (Preamp 1ON):
SSB, CW, RTTY 100 -500 kHz Less than 2.0 pV
(lOdBS/N) 1.8 -29.99 MHz Less than 0.16 pV
AM(l 0dBS/N) 0.5 -1.8 MHz Less than 13.0 pV
1.8 -29.99 MHz Less than 2.0 pV
FM (12 dB SINAD) 28 -29.99 MHz Less than 0.5 pV
•Squelch sensitivity (Preamp 1ON):
SSB, CW, RTTY, Less than 3.2 pV at threshold
AM
FM Less than 0.32 pV at threshold
•Selectivity (Normal filter selection):
SSB More than 2.4 kHz/ -6dB
Less than 4.0 kHz/ -60 dB
CW, RTTY More than 500 Hz/ -6dB
Less than 1.0 kHz/ -60 dB
AM More than 6.0 kHz/ -6dB
Less than 20.0 kHz/ -60 dB
FM More than 15.0 kHz/- 6dB
Less than 30.0 kHz/ -60 dB
•Spurious and image :More than 70 dB
rejection ratio
•Audio output power :More than 2.6 Wat 10% distortion
with an 8Qload
•RIT/ZITX :±9.999 kHz
variable range
ANTENNA TUNER
•Matching impedance range:
16.7-150Q unbalanced
(Less than VSWR 3:1)
•Minimum operating :8W
input power
•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.
1-1

SECTION 2DISASSEMBLY AND OPTION INSTALLATIONS
2-1 DISASSEMBLY INSTRUCTIONS
•TOP AND BOTTOM COVERS •PA UNIT
©Remove 6screws from the transceiver’s top and 40Disconnect the piug (P1) from J8 on the RF unit (bottom
screws from the sides, then remove the top cover. side).
®Turn the transceiver upside down. @Disconnect the plug (W1 )and flat cables (W4, W7) from
@Remove 8screws from the bottom cover, then remove the TUNER unit.
the bottom cover. (D Remove 2screws [e] and 1screw [f] to remove the PA
•REG UNIT •TUNER UNIT
©Remove 2screws [U to remove the speaker.
@Remove 2screws B, 2screws ®and 2screws B.
©Push the position “A” and pull the position “B” to release
2hooks.
©Disconnect 2connectors from the REG unit’s front and 1
connector (cable from the REG unit) from the front block,
then remove the REG unit.
©Disconnect the connector (P1) from J24 on the IF unit
(bottom side).
@Remove 1screw S] and 1screw El to remove the
TUNER unit.
2-1

•FRONT BLOCK
©Remove 3screws Q].
®Remove 2screws Q] and 2screws B, then remove the
right and left angles.
@Separate the front block and main chassis.
2-2 OPTION INSTALLATIONS
•UI-100 DSP UNIT
The UI-100 DSP UNIT provides noise reduction, DSP
modulation/demodulation, DSP filters, auto notch, auto
APF, etc. for the IC-775. The IC-775DSP has aDSP unit
as standard.
Install the DSP unit as follows:
©Remove the top cover as described on p. 2-1
.
©Connect the 3plugs (attached to the backside of the
front panel) to the appropriate connectors as shown
below.
m
(D Insert the DSP unit into the slots at the backside of the
main and sub dials.
0Tighten the 2supplied screws as shown below.
(D Replace the top cover.
I
After installation, read the instruction manual as for a
“DSP-equipped type” transceiver. The [AF LPF] switch
functions as the auto notch switch in SSB mode and the
auto APF switch in CW mode.
2-2

•OPTIONAL FILTER
After installing optional filters, the transceiver has 3* kinds
of selectivity for 2nd and 3rd IF filters to provide better S/N
(signal-to-noise ratio), or to reject nearby interference.
*FM mode: 2kinds of selectivity
Following optional filters are available.
IF Filter Passband width Used selectivity
2nd
FL-101 250 Hz/-6dB CW nar.
FL-102 6.0 kHz/-6dB SSB wide,
AM med., FM nar.
FL-223 1.9 kHz/-6 dB SSB nar.
3rd FL-53A 250 Hz/-6dB CW nar.
FL-222 1.9 kHz/-6 dB SSB nar.
When only 1filter is installed for selectivity, such as a
FL-101 installed but no FL-53A installed, optimum perform-
ance cannot be obtained for the selectivity and the twin
PBT function does not operate correctly. Both filters, such
as FL-101 and FL-53A, should be installed.
FILTER SELECTION
After the filter(s) are installed, activate the optional
mfilter(s) in H-set mode. If this is not correctly set, the
^installed filter(s) cannot be selected.
I
®Remove the top and bottom covers as described on
p. 2-1.
@Insert the filter(s) to the proper position. The locations
are shown in the figures below.
-The FL-53A and FL-222 must be installed in the proper
direction.
-The FL-101, FL-102 or FL-223 work regardless of the
direction they are installed in.
d) Replace the top and bottom covers.
FL-102 (or FL-101, FL-223) Installation
•UT-66 VOICE SYNTHESIZER UNIT
The UT-66 announces the operating frequency or selected
mode in aclear, electronically-generated voice (in English
or Japanese).
®Remove the top cover as described on p. 2-1
.
(D Plug the UT-66 into J1 on the MAIN unit (backside of
the S/RF meter) as shown in the figure at right.
@Replace the top cover.
0Set the language and speech speed in H-set mode.
2-3

CR-282 HIGH-STABILITY CRYSTAL UNIT
By replacing the original crystal unit with this unit, the total
frequency stability of the transceiver will be improved.
CR-282 frequency stability:
±0.5 ppm (-30°C to -i-60°C: -22T to -M40T)
®Remove the top and bottom covers as described on
p. 2-1.
(D Remove 10 screws from the PLL unit and the ribbon
cabie from J11; then turn over the PLL unit to see the
reverse side. (Fig. 1)
d) Unsoider the leads of the installed crystal, then remove
the crystal.
-Use adesoldering braid.
@Unsolder the 4positions on the PLL unit where the
CR-282 will be installed.
(D Install the CR-282 in the PLL unit, paying attention to
orientation.
-Symbols on the bottom of the CR-282 must be identically
matched with symbols on the P.C. board.
(D Bend the leads of the CR-282 at the foil side of the P.C.
board and soider them as shown in figure 2at right.
®Trim the ieads even with the soider points.
(D Replace the PLL unit, ribbon cabie and covers.
After changing the crystal unit, frequency adjustment is
necessary with L4 on the PLL unit.
-Refer to p. 5-2 for adjustment details.
NOTE: The CR-282 is an oven-heat-type crystal unit, and
the specified frequency stability described above is guar-
anteed 1min. after power ON.
Ribbon cable
(Fig. 1)
Solder points
(Fig. 2)
2-4

•AC VOLTAGE SELECTION
iAWARNING: DISCONNECT the AC power
Pcable from the transceiver and wait afew minutes
^before seiecting an AC power voltage.
The regulator unit in the IC-775/DSP can be switched to
120 or 230 VAC.
®Remove the REG unit as described on p. 2-1
.
(2) Remove the 16 screws to remove the internal shield
cover of the regulator unit.
(D Unplug the cable as shown in the diagram below, then
connect it to the desired voltage position.
@Change the AC fuse to an appropriate one.
©Replace the internal shield cover and plug in the 3
power connectors. Replace the regulator unit, then
check the movement of the [POWER] switch. Replace
the remaining units, covers and screws.
AWARNING: DO NOT forget to change the
AC fuse when you change the AC input voltage. An
incorrect fuse may pose afire hazard.
-12 AFGMB fuse for 100-120 Vversions
-5Ahigh breaking capacity fuse for 220-240 Vversions
•BACKUP BATTERY REPLACEMENT
The transceiver has alithium backup battery on the inside
of the front panel (MAIN unit) for retaining operating
conditions. The usual life of the backup battery is approxi-
mately 5years.
When the backup battery is exhausted, the transceiver
transmits and receives normally but cannot retain oper-
ating conditions except for memory channels.
PCAUTION: If the lithium battery is incorrectly re-
Pplaced, it could explode. Replace with aCR-2032 or
pequivalent type.
®Remove the top and bottom covers as described on
p. 2-1.
®Remove 8screws from the front panel as shown in
figure 1at right.
@Remove the front panel.
®Replace the backup battery as shown in figure 2at
right.
®Reassemble the front panel.
-Check that the [POWER] switch works smoothly.
®Replace the top and bottom covers.
PCAUTION: After replacing the lithium battery, turn
Ppower ON and OFF, otherwise, the lithium battery will
pbecome exhausted rapidly.
Topside :©
Bottom side :©
(© terminal is visible after installation.)
(Fig. 2)
2-5

SECTION 3INSIDE VIEWS
•BOTTOM VIEW
3-1