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CAUTION:Before servicing receivers covered by this ser-
vice manual its supplements and addenda,read and follow
the SAFETY PRECAUTIONS on page 3 of this publication.
NOTE:lf unforeseen circumstances create conflict between
the following servicing precautions and any of the safety
precautions on page 3 of this publication, always follow
the safety precautions. Remember:Safety First.
General Servicing precautions
1.Always unplg the receiver AC power cord from the AC
power source before:
a.Removing or reinstalling any component,circuit board
module or any other receiver assembly.
b.Disconnecting or reconnecting any receiver electrical
plug or other electrical connection.
c.Connecting a test substitute in parallel with an electro
lytic capacitor in the receiver.
CAUTION: A wrong part substitution or incorrect polarigy
installation of electroiytic capacitors may result in an
expiosison hazard.
d. Discharging the picture tube anode.
2. Test high voltage only by measuring it with an appropri
ate high voltage meter or other voltage measuring de
vice (DVM,FETVOM,etc)equipped with a suitable high
voltage probe.
Do not test high voltage by “drawing an arc”.
3. Discharge the picture tube anode only by (a)first con
necting one end of an insulated clip lead to the degauss
ing or kine aquadag grounding system shield at the point
where the picture tube socket ground lead is connected,
and then (b)otuch the other end of the insulated dip lead
to the picture tube anode button, using an insulating
handie to avoid personal contact with high voltage.
4. Do not spray chemicals on or near this receiver or any of
its assemblies.
5. Unless specified otherwise in this service manual,clean
electrical contacts only by applying the following mixture
to the contacts with a pipe cleaner,cotton-topped stick
or comparable nonabrasive applicator:10%(by volume)
Acetone and 90%(by volume)isopropyl alcohol(90%-90%
strength)CAUTION:This is a flammable mixture.
Uniess specified otherwise in this service manual,lubri
cation of contacts in not require
6. Do not defeat any plug/socket B+voltage interlocks with
which receivers covered by this service manual might be
equipped.
7.Do not apply AC power to this instrument and/or any of
its electrical assemblies unless all solid-state device heat
sinks are correctly installed.
8.Always connect the test receiver ground lead to the re
ceiver chassis ground before connecting the test receiver
positive lead.
Always remove the test receiver ground lead last.
9.Use with this receiver only the test fixtures specified in
this service manusl.
CAITION:Do not connect the test fixture ground strap to
any heatsink in this receiver.
Electrostatically Sensitive(ES)Devices
some semiconductor(solid state)devices can be damaged
SERVICING PRECAUTIONS
easily called Electrostatically Sensitive(ES)Devices.Ex-
amples of typical ES devices are integrated circuits and
some field effect traansistors and semicounductor
“chip”components.The following techniques should be used
to help reduce the incidence of component damage caused
by static by static electricity.
1.lmmediately before handing any semiconductor com-
ponent or semiconducotr-equipped assembly.drain off any
electostatic charge on your body by touching a known earth
ground.Alematively.
Obtain and wear a commercially available discharging
wrisl strap device.which should be removed to prevent po-
tential shock reasons prior to applying power to the unit
under test.
2.After removing an electrical assembly epuipped with
ESdevice.place the assembly on a conductive surtace such
as aluminum foil.to prevent electrostatic charge buildup or
exposure of the assembly.
3.Use only a grounded-tip soldering iron to solder or
unsolder ES devices.
4.Use only an anti-static type solder removal device.
Some solder removal devices not classified as “anti-
static”can generate electrecal charges sufficent to demage
ES devices.
5.Do not use freon-propelled chemicals.These can gen-
erate electrical charges srffient to damage ES devices.
6.Do not remove a repalcement ES device from its pro-
tective package until immediately before you are ready to
install it.(Most replacement ES devices are package with
leads electricall shorted together by conductive foam,
aluminumfoil or comparable conductive material).
7.lmmediately befor removing the protective material
from the ieads of a replacement ES device touch the pro-
tective material to the chassis or circuit assembly into which
the device will be installed.
CAUTION:Be sure no power is applied to the chassis or
circuit and observe all other safety precautions.
8.Minmize bodily motions when handling unpackaged
replacement ES devices.(Otherwise harmless motion
such as the bruching together of your clothes fabric or the
lifting of your foot from a carpeted floor can generate static
electricity sufficient to damage an ES device.)
General Soldering Guidelines
1.Use a grounded-tip.low-wattage soldering iron and
appropriate tip size and shape that will maintan tip
temperture withen the range or 500k to 600k.
2.Use an appropriate gauge of RMA resin-core solder
composed of 60parts tin/40parts lead.
3.Keep the soldering iron tip clean and well tinned.
4.Thorohly clean the surfaces to be soldered Use a mall
wirebristle(0.5inch.or 1.25cm)brush with a metal handle.
Do not use freon- propelled spray-on cleaners.
5.Use the following unsoldering technique
a.Allow the soldering iron tip to reach normal temperature
(500k to 600k)
b.Heat the component lead until tne solder melts.
c.Quickly draw the melted solder with an anti-statlc,suc tion-
