Sharp 37GQ-20FP, Service Manual

3

37GQ-20FP

SERVICING OF HIGH VOLTAGE SYSTEM AND PICTURE TUBE

Maintenance and repair of this receiver should be done by qualified service personnel only.

When servicing the high voltage system, remove static charge from it by connecting a 10K ohm resistor in
series with an insulated wire (such as test probe) between picture tube ground tag and high voltage lead.
(AC line cord should be disconnected from AC outlet).

1. The Picture tube in this receiver employs Integral Implosion protection.
2. Replace with tube of the same type number for continued safety.
3. Do not lift picture tube by the neck.
4. Handle the picture tube only when wearing shatterproof goggles and after discharging the high
    voltage completely.

X-RAY

This receiver is designed so that any X-Ray radiation is kept to an absolute minimum. Since certain malfunctions
and servicing may produce potentially hazardous radiation with prolonged exposure at close range, the following
precautions should be observed:

1. When repairing  the circuit, be sure not to increase the high voltage to more than 25.5 KV, (at beam
    1000

µΑ)

 for the set.

2. To keep the set in a normal operation, be sure to make it function on 22.4KV

±

1.5KV (at beam

   800

µΑ) 

 in the case of the set. The set has been factory - adjusted to the above mentioned high

   voltage. Always check the high voltage if there is any possibility that it might have changed as a
    result of the repair.
3. Do not substitute a picture tube with unauthorized types and/or brands which may cause excess
    X-Ray radiation.

BEFORE RETURNING THE RECEIVER

In addition to the above checks, the following safety checks should also be carried out before  returning the
unit to the user.

1. Inspect all leads and dress to make certain that the leads are not pinched or that hardware is not
   logged between the chassis and other metal parts.
2. Inspect all protective devices such as non-metallic control knobs, insulating fish papers, cabinet
   backs, adjustment and compartment covers or shields, insolation resistor-capacity networks,
   mechanical insulators etc.

IMPORTANT SERVICE NOTES