Icom IC-746PRO Manual

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 1 of 7
Technical Information
To : ICOM Distributors
From : ICOM Inc. / Export Department
Ref No.: SEN-015-03
Date : December 17, 2003
Re. Improvement of the PA Driver for the IC-746PRO/ 7400 series.
Thank you very much for your continuous strong promotion for our products in your market.
The following is the information for the improvement of the PA driver for the IC-746PRO/ 7400 series.
Model:
All versions of the IC-746PRO/ 7400 series.
Symptom:
No RF power output.
Cause:
The driver transistor on the PA stage will be damaged when the transceiver is used in a high
temperature environment and transmits continuously.
Procedure of this improvement:
For solution of this problem, we have reduced the current drain of the circuitry on the PA stage.
The following is the procedures for this improvement.
(1) Replace the parts as shown in the parts list and parts location.
(2) Replace the MP34 screws which is fixed to the DRV board.
(3) Adjust PA idling current to 1.5A from 2.5A.
Service handling necessary:
[ ] Yes [X] No

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 2 of 7
Replace following parts.
Board
Parts
Number Parts Number (Old) QTY Parts Number(New) QTY
Action
Taken Version
CHASSIS MP34 8810003170 2 8810003370 2 Replaced All versions
SCREW(A) 3X8 SCREW(C) 3X8
PA L2 620003260 1 6200001830 1 Replaced All versions
NL322522T 101J 100U NL322522T 100J 10U
PA L6 2040000490 1 6140002220 1 Replaced All versions
EXC-ELDR25C LR-270
PA R41 7030010660 1 0 Removed #01 only
6.8 ERJ1TY None
PA R41 7030010570 1 0 Removed #02, 03, 04, 05, 08, 09
4.7 ERJ1TY None and 10 only
PA R41 0 7030010660 1 Added All versions
None 6.8 ERJ1TY
PA R42 7030010660 1 0 Removed #01 only
6.8 ERJ1TY None
PA R42 7030010570 1 0 Removed #02, 03, 04, 05, 08, 09
4.7 ERJ1TY None and 10 only
PA R42 0 7030010660 1 Added All versions
None 6.8 ERJ1TY
CTRL D25 0 1750000810 1 Added All versions
None UM9957
CTRL D26 0 1750000810 1 Added All versions
None UM9957
CTRL R154 7030003480 1 7030003440 1 Replaced All versions
2.2K ERJ3GE 1K ERJ3GE
DRV R11 7030000280 1 0 Removed All versions
150 MCR10 None

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 3 of 7
Parts Location on the PA board. (L6, L2, R41 and R42)
Schematic Diagram of the PA board. (L6)

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 4 of 7
Parts Location on the CTRL board. (D25, D26 and R154)
Schematic Diagram of the CTRL board. (D25 and D26)

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 5 of 7
Parts Location on the DRV board. (R11)
Schematic Diagram of the DRV board. (R11)

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 6 of 7
Replace the MP34 screws on the CHASSIS board which is fixed to the DRV board.
Adjust PA Idling current to 1.5A from 2.5A.

Icom Inc.
1-1-32, Kamiminami, Hirano-ku, Osaka, 547-0003
JAPAN
Phone : [phone] Fax : [phone]
URL : http://www.icom.co.jp/
Page. 7 of 7
Updated Serial Number:
This modification has not yet been applied in production units.
However, the serial number of improved units will be announced later.