CAUTION: Before servicing instruments covered by this
service data 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 Guidelines
1.Always unplug the instrument AC power cord from the AC power source before:
a.Removing or reinstalling any component, circuit board, module, or any other instrument assembly.
b.Disconnecting or reconnecting any instrument electrical plug or other electrical connection.
c.Connecting a test substitute in parallel with an electrolytic capacitor in the instrument.
CAUTION: A wrong part substitution or incorrect
polarity installation of electrolytic
capacitors may result in an explosion hazard.
d.Discharging the picture tube anode.
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.” The H.V. Distribution Box has an internal 400M0
resistor (bleeder resistor) connected from the high voltage to ground. After power is removed from the instrument the high voltage will discharge through the high voltage bleeder resistor. If the tubes have high voltage after power is removed, then the bleeder resistor is defective or the bleeder ground is disconnected.
3.Discharge the picture tube’s anode at any of the R, G, or B outputs on the H.V. Distribution Box only by (a) first
connecting one end of an insulated clip lead to the degaussing or kine aquadag grounding system shield at the point where the picture tube socket ground lead is
connected, and then (b) touch the other end of the insulated clip lead to the picture tube high voltage distribution box R, G, or B output, using an insulated handle to avoid personal contact with high voltage.
4.Do not spray chemicals on or near this instrument or any of its assemblies.
5.Unless specified otherwise in these service data, clean electrical contracts by applying the following mixture to
the contacts with a pipe cleaner, cotton-tipped stick or
comparable nonabrasive applicator: 10% (by volume) Acetone and 90% (by volume) isopropyl alcohol (90%- 99% strength).
CAUTION: This is a flammable mixture. Unless specified otherwise in these service data, lubrication of contacts is not required.
6.Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service data 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 instrument ground lead to the appropriate instrument chassis ground before connecting the test instrument positive lead. Always remove the test instrument ground lead last.
9.Use with this instrument only the test fixtures specified in this service data.
CAUTION: Do not connect the test fixture ground strap to any heatsink in this instrument.
Electrostatically | Sensitive | (ES) | Devices | | | | |
Some | semiconductor | | (solid | state) | devices | can | be | damaged |
easily | by | static | electricity. Such components | commonly | are |
called | Electrostatically | | Sensitive | (ES) Devices. | Examples | of |
typical | ES | devices | are integrated | circuits | and | some field- |
effect transistors | and | semiconductor | “chip” | components. | The |
following | | techniques | | should | be | used | to | help | reduce | the |
incidence | of component | damage | caused | by static | electricity. |
1. Immediately before handling any semiconductor
component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a
known earth ground. Alternatively, obtain and wear a
commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test.
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 exposure of the assembly.
3.Use only a grounded-tip soldering iron to solder or desolder ES devices.
4.Use only can anti-static type solder removal device. Some solder removal devices not classified as “anti-
static” can generate electrical charges sufficient to damage ES device.
5.Do not use freon-propelled chemicals. These can
generate electrical charges sufficient to damage ES devices.
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 electrically 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
replacement 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 sufficient to damage an ES device.)
