SERVICING PRECAUTIONS
CAUTION: Before servicing receivers covered by this serviceprevent potential shock reasons prior to applying power to the
manual and its supplements and addenda, read and follow theunit under test.
SAFETY PRECAUTIONS on page 3 of this publication.2. After removing an electrical assembly equipped with ES
NOTE: If unforeseen circumstances create conflict between thedevices, place the assembly on a conductive surface such as
following servicing precautions and any of the safety precautions onaluminum foil, to prevent electrostatic charge buildup or
page 3 of this publication, always follow the safety precautions.exposure of the assembly.
Remember: Safety First.3. Use only a grounded-tip soldering iron to solder or unsolder ES
devices.
General Servicing Precautions4. Use only an anti-static type solder removal device. Some solder
1. Always unplug the receiver AC power cord from the AC powerremoval devices not classified as "anti-static" can generate
source before;electrical charges sufficient to damage ES devices.
a. Removing or reinstalling any component, circuit board5. Do not use freon-propelled chemicals. These can generate
module or any other receiver assembly.electrical charges sufficient to damage ES devices.
b. Disconnecting or reconnecting any receiver electrical plug or6. Do not remove a replacement ES device from its protective
other electrical connection.package until immediately before you are ready to install it.
c. Connecting a test substitute in parallel with an electrolytic(Most replacement ES devices are packaged with leads
capacitor in the receiver.electrically shorted together by conductive foam, aluminum foil
CAUTION: A wrong part substitution or incorrect polarityor comparable conductive material).
installation of electrolytic capacitors may result in an7. Immediately before removing the protective material from the
explosion hazard.leads of a replacement ES device, touch the protective material
to the chassis or circuit assembly into which the device will be
2. Test high voltage only by measuring it with an appropriate highinstalled.
voltage meter or other voltage measuring device (DVM,CAUTION: Be sure no power is applied to the chassis or circuit,
FETVOM, etc) equipped with a suitable high voltage probe.and observe all other safety precautions.
Do not test high voltage by "drawing an arc".8. Minimize bodily motions when handling unpackaged
3. Do not spray chemicals on or near this receiver or any of itsreplacement ES devices. (Otherwise harmless motion such as
assemblies.the brushing together of your clothes fabric or the lifting of your
4. Unless specified otherwise in this service manual, cleanfoot from a carpeted floor can generate static electricity
electrical contacts only by applying the following mixture to thesufficient to damage an ES device.)
contacts with a pipe cleaner, cotton-tipped stick or comparable
non-abrasive applicator; 10% (by volume) Acetone and 90% (byGeneral Soldering Guidelines
volume) isopropyl alcohol (90%-99% strength)1. Use a grounded-tip, low-wattage soldering iron and appropriate
CAUTION: This is a flammable mixture.tip size and shape that will maintain tip temperature within the
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Unless specified otherwise in this service manual, lubrication ofrange or 500F to 600F.
contacts in not required.2. Use an appropriate gauge of RMA resin-core solder composed
5. Do not defeat any plug/socket B+ voltage interlocks with whichof 60 parts tin/40 parts lead.
receivers covered by this service manual might be equipped.3. Keep the soldering iron tip clean and well tinned.
6. Do not apply AC power to this instrument and/or any of its4. Thoroughly clean the surfaces to be soldered. Use a mall wire-
electrical assemblies unless all solid-state device heat sinks arebristle (0.5 inch, or 1.25cm) brush with a metal handle.
correctly installed.Do not use freon-propelled spray-on cleaners.
7. Always connect the test receiver ground lead to the receiver5. Use the following unsoldering technique
chassis ground before connecting the test receiver positivea. Allow the soldering iron tip to reach normal temperature.
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lead.(500F to 600F)
Always remove the test receiver ground lead last.b. Heat the component lead until the solder melts.
8. Use with this receiver only the test fixtures specified in thisc. Quickly draw the melted solder with an anti-static, suction-
service manual.type solder removal device or with solder braid.
CAUTION: Do not connect the test fixture ground strap to anyCAUTION: Work quickly to avoid overheating the
heat sink in this receiver.circuitboard printed foil.
6. Use the following soldering technique.
Electrostatically Sensitive (ES) Devicesa. Allow the soldering iron tip to reach a normal temperature
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Some semiconductor (solid-state) devices can be damaged easily(500F to 600F)
by static electricity. Such components commonly are calledb. First, hold the soldering iron tip and solder the strand against
Electrostatically Sensitive (ES) Devices. Examples of typical ESthe component lead until the solder melts.
devices are integrated circuits and some field-effect transistors andc. Quickly move the soldering iron tip to the junction of the
semiconductor "chip" components. The following techniquescomponent lead and the printed circuit foil, and hold it there
should be used to help reduce the incidence of componentonly until the solder flows onto and around both the
damage caused by static by static electricity.component lead and the foil.
1. Immediately before handling any semiconductor component orCAUTION: Work quickly to avoid overheating the circuit
semiconductor-equipped assembly, drain off any electrostaticboard printed foil.
charge on your body by touching a known earth ground.d. Closely inspect the solder area and remove any excess or
Alternatively, obtain and wear a commercially availablesplashed solder with a small wire-bristle brush.
discharging wrist strap device, which should be removed to
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ACEC
