Section
IV
Figure
4-1
Model 456A
SERVICI N G ETCHED CIRCUIT BOARDS
Exces s ive heat or pressure can lift th e copper strip from the boa rd. Avoid damage by us ing a low power
soldering iron (50 watts ma ximum) and following these instruc tions. Copper that lifts off the board should
be cemented in place with a quick drying acetate base cement having good electrical insula ting properties.
A break in the copper should be repaired by soldering a short length of tinned copper wire across the break.
Use only high qua lity rosin core solder when repa iring etched circuit boa rds .
NEVER
USE
PASTE
FLUX.
After soldering. clea n off any excess flu x and coat [he repaired area with a high quality electrica l varnish
or lacquer.
When replacing components with multiple mounting pins such as tube sockets, electrolytic capacitors , and
potentiometers, it will be neces sa ry to lift each pin slightly, working around the components severa l times
u ntil it is free.
WARNING:
If
the specific instructions ou tlined in the steps below regarding etched circuit boards without
eyelets are not followed, e xtensive damage to the etched c ircuit board will result.
1.
Apply heat sparingly to lead of component to be
replaced. If lead of component passes through
an eyelet in the circuit boa rd. apply hea t on com
ponent side of board . If lead of component does
not pass through an eyelet. a pply heat to con
dUctor side of board .
3.
Bend clea n tinned leads on new part a nd care
fu lly insert through eyelets o r holes in board .
2. Reheat solder in vacant eyelet a nd quickly in
sert a small awl to clean inside of hole. If hole
does not have an eyelet. insert awl or a
#57
drill from conductor side of boa rd.
4.
Hold part against board (avoid overheating) and
solder lea ds. Apply heat to component leads on
correct side of boa rd as explained in step 1.
In the event that either the circu it board ha s been damaged or the convenrional method is impractical, use
method shown below. This is especially applicable for circuit boards without eyelets.
I.
Clip lead a s shown below.
2. Bend protruding leads upward. Bend lead of
new component around protruding lead . Apply
solder using a pair of long nose pliers a s a
heat sink.
s�����
This procedure is u s ed in the field only as an a lterna te means of repair. It is not used within the fac tory.
Figure
4-1.
Servicing Etched Circuit Boards
4
-0
00395-1
