1
Introduction
This manual provides technical information necessary for ser-
vicing the VX-424A (LTR
®
) Series FM Transceiver.
Servicing this equipment requires expertise in handling surface-
mount chip components. Attempts by non-qualified persons to
service this equipment may result in permanent damage not cov-
ered by the warranty, and may be illegal in some countries.
Two PCB layout diagrams are provided for each double-sided
circuit board in the transceiver. Each side of is referred to by the
type of the majority of components installed on that side (“lead-
ed” or “chip-only”). In most cases one side has only chip com-
ponents, and the other has either a mixture of both chip and lead-
ed components (trimmers, coils, electrolytic capacitors, ICs, etc.),
or leaded components only.
While we believe the technical information in this manual to be
correct, VERTEX STANDARD assumes no liability for dam-
age that may occur as a result of typographical or other errors
that may be present. Your cooperation in pointing out any in-
consistencies in the technical information would be appreciated.
LTR
®
is a registered trademark of E.F Johnson Company.
©
2009 VERTEX STANDARD CO., LTD. EC071N95C
Service Manual
VX-424A (LTR
®
) Series
VHF FM Transceiver
Specifications ..........................................................2
Exploded View & Miscellaneous Parts ..............3
Block Diagram .........................................................5
Circuit Description ................................................7
Alignment ................................................................9
Contents
Board Unit (
Schematics, Layouts & Parts
)
MAIN-2 Unit ............................................................ 25
DUMMY Unit .......................................................... 47
Optional Units (
Schematics, Layouts & Parts
)
FVP-25 Encryption / DTMF Pager Unit .............. 48
VERTEX STANDARD CO., LTD.
4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan
VERTEX STANDARD
US Headquarters
10900 Walker Street, Cypress, CA 90630, U.S.A.
YAESU UK LTD.
Unit 12, Sun Valley Business Park, Winnall Close
Winchester, Hampshire, SO23 0LB, U.K.
VERTEX STANDARD HK LTD.
Unit 5, 20/F., Seaview Centre, 139-141 Hoi Bun Road,
Kwun Tong, Kowloon, Hong Kong
VERTEX STANDARD
(
AUSTRALIA
)
PTY., LTD.
Normanby Business Park, Unit 14/45 Normanby Road
Notting Hill 3168, Victoria, Australia
16 key Version 4 key Version
Important Note
This transceiver was assembled using Pb (lead) free solder, based on the RoHS specification.
Only lead-free solder (Alloy Composition: Sn-3.0Ag-0.5Cu) should be used for repairs performed on this appara-
tus. The solder stated above utilizes the alloy composition required for compliance with the lead-free specification,
and any solder with the above alloy composition may be used.
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