Nobel Tv Circuit Diagram Manual

Search service manual

General Guidance An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line.

Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks. It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation.

If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified.

When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10mm away from PCB.

Keep wires away from high voltage or high temperature parts.

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
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 electrolytic
capacitor in the receiver.
CAUTION: A wrong part substitution or incorrect polarity
installation of electrolytic capacitors may result in an
explosion 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, cotton-tipped stick or comparable
non-abrasive applicator; 10% (by volume) Acetone and 90% (by
volume) isopropyl alcohol (90%-99% strength)
CAUTION: This is a flammable mixture.
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 solid-state device heat sinks are
correctly installed.

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.