Daewoo 901D, Service Manual

Page: 5 / 67

SERVICING PRECAUTIONS
3
General Servicing Precautions
1. Always unplug the 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 electrical plug or other electrical connection.
c. Connecting a test substitute in parallel with an electrolytic capacitor in the instrument.
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”.
3. Discharge the picture tube anode only by: (a) first connecting one end of an insulated clip lead to the
degaussing or line grounding system shield at the point where the picture tube socket ground lead is
connected, and then (b) touching the other end of the insulated clip lead to the picture tube anode button, using
an insulating handle to avoid personal contact with high voltage.
4. Do not any spray chemicals on or near this instrument or any or its assemblies.
5. Unless specified otherwise in this service manual, clean electrical contacts 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).
6. Do not defeat any plug/socket B+ voltage interlocks with which instruments 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 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 only the test fixtures specified in this service manual with this instrument.
CAUTION: Before servicing instruments covered by this service manual, its supplements and addendum,
read and follow the SAFETY PRECAUTIONS of this manual.
NOTE: If unforeseen circumstances create conflict between the following servicing precautions and any of the
safety precautions on page 1 of this manual, always follow the safety precautions.
Remember: Safety First.
CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in
a explosion hazard.
CAUTION: This is a flammable mixture. Unless specified otherwise in this service manual, lubrication of
contacts is not required.
CAUTION: Do not connect the test fixture ground strap to any heatsink in this instrument.