Servicing Precautions - RCA SelectaVision VideoDisc SFT 100 Service Data

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SERVICING PRECAUTIONS
General
The Solid State devices utilized by this player are selected to рег-
form efficiently in their specific circuit function.
Order replacement items by stock number from your Authorized
RCA Distributor.
General precautions to observe when servicing this player
follows. More specitic information is outlined under those special
sections associated with this instrument.
1. When servicing this instrument always use an isolation
transformer.
2. Do not remove or insert any component with AC power ap-
plied to this instrument.
3. Do not bridge electrolytic capacitors with AC power applied
to player since resultant surges may damage the solid state
devices.
4. When a solid state device is equipped with a heatsink, do not
operate the instrument with that heatsink removed.
5. Soldering irons utilized where transistors and integrated cir-
cuits are concerned should be rated at no more than 35
watts. They should be grounded in such а manner that no
voltage will be applied to the device during the soldering or
desoldering operation. These precautions are necessary to
prevent any possible damage to the device due to excessive
heat and/or voltage.
6. Donot use spray type chemicals (especially circuit coolants)
as trouble-shooting aids in the vicinity of component con-
nectors.
To Clean Connector Contacts apply the following described mix-
ture.
Use a mixture of 10% (by volume) Acetone and 90% (by volume)
isopropyl Alcohol (strength of 90 to 99%).
Use a pipe cleaner soaked with the above solution to clean plug
contacts. Further lubrication of contacts is not required.
7. Always connect the ground lead of a test instrument to the
ground point before connecting the positive lead: conver-
sely, always remove the ground lead of a test instrument last.
Handling Integrated Circuits
Thoughtful handling procedures and some inexpensive equip-
ment can go a long way towards reducing static electricity
damage to integrated circuits. Basic principles include steps to
prevent the frequent discharging of static electricity from the
human body (and other objects) and avoiding the use of static
producing accessories. The following procedures are effective in
reducing the possibility of integrated circuit damage due to static
electricity:
1. Just before touching any component or circuit board, touch
the metal chassis (observe line isolation precautions) to en-
sure your body is not statically charged.
2. When removing circuit boards from the instrument. place
them on a conductive surface such as aluminum foil. Do not
place them directly on the floor, carpet or workbench.
3. Touch the metal chassis (observe line isolation precautions)
just before picking up a circuit board or component for inser-
tion.
4. When removing or replacing integrated circuits, grounded-tip
solder irons are absolutely essential.
5. Some "solder suckers" generate up to 20,000 volts of charge
when triggered and should not be used. Even when the !C
being removed is known to be bad, a solder sucker can gener-
ate enough static to damage other components on the board.
Anti-static solder suckers are available and are essential tor
IC work.
6. Replacement integrated circuits are packaged in conductive
foam or with aluminum foil. Do not remove the IC from its pro-
tective package until it is ready to be used. Just before remov-
ing the IC, touch the conductive foam to the chassis or circuit
board into which it will be inserted. This can be done by
touching the board with one hand and the conductive
package with the other.
7. Tryto minimize motion when handling unpackaged integrated
circuits. When seated, the simple action of lifting your feet
from the floor can generate static electricity. Clothes readily
generate static electricity when brushed against other ob-
jects.
8. Do not use freon propelled sprays on the circuit boards or
chassis. Freon sprays can generate more than 5,000 volts of
static electricity. Even when an IC is in a protective package
or soldered into a circuit board, a freon propelled spray can
generate static electricity which could damage internal com-
ponents not directly connected to the IC pins. A short bristle
brush (1/2 inch or 1.25 centimeters) with a metal handle is a
safer method о! clearing debris.
NOTE: In situations where the above guidelines аге in conflict
with safe servicing procedures, the safety rules come
first.
Printed Circuit Board Soldering Rules — General
1. Use a low-wattage soldering iron rated at no more than 35
watts.
2. Keep the soldering iron tip well-tinned and clean at all times.
3. Keep the surface to be soldered clean.
4. Tounsolder, heat the component leads until the solder melts.
Draw solder away from the component joints using a
grounded solder sucker, solder braid or gravity method. Do
not overheat the circuit board printed foil.
5. То resolder, heat the component lead first to melt the solder;
then hold the iron to the junction of the component lead and
the printed circuit foil until the solder blends. Do not overheat.
6. Inspect the serviced area and remove excess or splashed
solder.
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