Heathkit SB-401 Assembly Manual page 141

117
HEATHKl:T®
NOTE: In an extreme case where you are
unable to resolve a difficulty, refer to the
Service and Warranty section of the "Kit
Builders GUide", and to the "Factory Repair
Service" information on Page 120of this Manual.
6. Check for bits of solder, wire ends or other
foreign matter which may be lodged in the
wiring or bridging a foil on the circuit
board.
5. Check the values of the parts. Be sure that
the proper part has been wired into the cir-
cuit' as shown in the pictorial diagrams and
as called out in the wiring instructions.
Breaks in the foil of the circuit boards can easily
be detected by placing a bright light under the
foil side of the board and looking through the
board from the lettered side. A break wil ·l
appear as a hair-line crack in the foil.
4. Check the tubes with a tube tester or by
substitution of tubes of the same types and
known to be good.
NOTE: To aid in servicing or troubleshooting the
Transmitter, refer to the Resistance and Volt-
age Charts (fold-out from Pages 145 and 146),
the Circuit Board X-Ray Views on Page 139,
and the Chassis Photographs shown in Figures
6-21 through 6-27 on Pages 141 through 144.
3. Check to be sure that all tubes are in their
proper locations. Make sure that all tubes
light up properly.
9. Retighten all hardware.
2. About 90% of the kits that are returned for
repair, do not function properly due to poor
connections and soldering. Therefore, many
troubles can be eliminated by reheating all
connections to make sure that they are sol-
dered as described in the Soldering section
of the Kit Builders GUide.
8. Check the antenna and coaxial cable for an
open or shorted connection.
7. A review of the Circuit Description will
prove helpful in indicating where to look
for trouble.
1. Recheck the wiring. Trace each lead in
colored pencil on the Pictorial as it is
checked. It is frequently helpful to have
a friend check your work. Someone who is
not familiar with the unit may notice some-
thing consistently overlooked by the builder.
DIFFICULTY
CASE
IN