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SERVICING PRECAUTIONS
CAUTION: Before servicing receivers covered by this service manual and its supplements and addenda, read and follow the SAFETY PRECAUTIONS on page 3 of this publication.
NOTE: If 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 unplug the receiver AC power cord from the AC power source before;
a.Removing or reinstalling any component, circuit board mod- ule 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 electrolytic capacitor in the receiver.
CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explo- sion hazard.
2.Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM, etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc".
3.Do not spray chemicals on or near this receiver or any of its assemblies.
4.Unless specified otherwise in this service manual, clean electrical contacts only by applying the following mixture to the contacts with a pipe cleaner,
Unless specified otherwise in this service manual, lubrication of contacts in not required.
5.Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be equipped.
6.Do not apply AC power to this instrument and/or any of its electrical assemblies unless all
7.Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead.
Always remove the test receiver ground lead last.
8.Use with this receiver only the test fixtures specified in this service manual.
CAUTION: Do not connect the test fixture ground strap to any heat sink in this receiver.
Electrostatically Sensitive (ES) Devices
Some semiconductor
1.Immediately before handling any semiconductor component or
2.After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or expo- sure of the assembly.
3.Use only a
4.Use only an
5.Do not use
6.Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electri- cally shorted together by conductive foam, aluminum foil or comparable conductive material).
7.Immediately before removing the protective material from the leads of a replacement ES device, touch the protective 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.Minimize bodily motions when handling unpackaged replace- ment ES devices. (Otherwise harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity suf- ficient to damage an ES device.)
General Soldering Guidelines
1.Use a
2.Use an appropriate gauge of RMA
3.Keep the soldering iron tip clean and well tinned.
4.Thoroughly clean the surfaces to be soldered. Use a mall wire- bristle (0.5 inch, or 1.25 cm) brush with a metal handle.
Do not use
5.Use the following unsoldering technique
a.Allow the soldering iron tip to reach normal temperature.
(500 °F to 600 °F)
b.Heat the component lead until the solder melts.
c.Quickly draw the melted solder with an
6.Use the following soldering technique.
a.Allow the soldering iron tip to reach a normal temperature (500 °F to 600 °F)
b.First, hold the soldering iron tip and solder the strand against the component lead until the solder melts.
c.Quickly move the soldering iron tip to the junction of the component lead and the printed circuit foil, and hold it there only until the solder flows onto and around both the compo- nent lead and the foil.
CAUTION: Work quickly to avoid overheating the circuit board printed foil.
d.Closely inspect the solder area and remove any excess or splashed solder with a small
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