home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Libris Britannia 4
/
science library(b).zip
/
science library(b)
/
HAM_RAD
/
3176.ZIP
/
ICOM2.ZIP
/
IC761.3
< prev
next >
Wrap
Text File
|
1990-10-14
|
4KB
|
199 lines
Model: IC-761 Revised 11-9-89
Division: Amateur
Note: This service bulletin is meant for technical per-
sonnel with experience working on solid state com-
munications equipment. Damage caused by im-
properly installing this modification may cause
ICOM to charge for subsequent repairs to the
product. ICOM does not warrant this modification.
Bulletin #: 8988-001
Date: March 29, 1988
Subject: Poor sensitivity on all bands EXCEPT 14 MHz.
Information: On the main PLL Board VCO there is a shield under
the board. This shield has a small grounding
prong that may come in contact with the bottom of
J4.
Procedure
1. Gain access to the bottom side of the VCO on the PLL Board.
2. Re-position the grounding tab (prong) so that it does not
contact the bottom of J4.
3. Reassemble the radio and check sensitivity on all bands. It
should be normal.
Note: This condition has been noted on some units with serial
numbers close to 1239.
Bulletin #: 24287-001A
Subject: Larger relay for keying non-ICOM amplifiers
Procedure
1. Replace RL 2 (currently labeled OMR 109) on the PA Connector
Board with a SY-12 relay (ICOM P/N 921-04696). This relay
is larger but can be squeezed into place. Glue this relay
to the board with RTV.
Bulletin #: 24287-002
Date: August 29, 1987
Subject: Speed up rise time of CW transmit waveform when
the radio is in the full-break-in mode
Procedure
1. Remove the bottom cover from the radio.
2. Remove the main board from the radio.
3. Replace R32 (currently 180K) with a 82K 1/8 watt resistor
(ICOM P/N 915-01123).
Bulletin #: 24287-003
Subject: When the B VFO is being used the LED for the A VFO
flickers
Procedure
1. Replace the following parts on the Display Board
Reference Current New
Designation Value Value
C10 .0047 mf .68 mf
C11 .0047 mf .68 mf
C12 .0047 mf .68 mf
Bulletin #: 24287-003A
Subject: While receiving a strong signal the receiver may
oscillate due to AGC time constant delay
Procedure
1. Replace R34 (currently 12K) on the RF Board with a 56K
resistor.
2. Replace C30 (currently .47 mf) on the RF Board with a 2.2 mf
50V electrolytic capacitor.
Bulletin #: 24287-004
Subject: When using the IC-761 with other manufacturers
linear amplifiers the ALC may not be controlled
properly
Procedure
1. Add a 10K resistor on the main board from the base of Q92
(2SA 1048) to ground.
Bulletin #: 24387-001
Subject: CW rise and fall time are too steep
Procedure
Write ICOM's Customer Service Department for a copy of this
service bulletin.
Bulletin #: 24387-001A
Subject: Display malfunctions when power is turned on
Information: When the radio is turned off the response time of
the reset line is slower than the CPU 5V line.
Data in RAM is changed by timing delay on the
reset line.
Procedure
Write to ICOM's Customer Service Department for a copy of
this service bulletin.