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VOLTAGE
SELECTOR
PLUG
& FUSE
REPLACEMENT
1.
ACLINE FUSE
When the unit does not function due to a blown fuse, remove the power cord and replace the old fuse on the fuse
holder with a new once. Use a 1.0A fuse for 220V, 240V; 2.0A fuse for 110V.
NOTE: When replacing the fuse, never use a copper wire or other fuse of improper capacity.
2.
CIRCUIT PROTECTION FUSE
Provied on the chassis near the Power Transformer. If sound through speakers are cut, the protection fuse has
been blown. Turn the power switch off immediately remove the cabinet by loosing the screws on the side of the
set, and check for a short on the connections between speaker enclosures and amplifier.
If short circuited repair it and replace the protection fuse.(0.5A).
3.
VOLTAGE CHANGING
Be sure to check the pre-set voltage before operating the set. If the voltage, is different from your local voltage
according to the voltage selector plug as follows:
1)
Disconnect the AC power cord from the outlet in order to prevent an electric shock.
2)
Remove the plug cover by unscrewing screw on it. (See Fig.9)
3)
Pull out the selector plug cover and reinsert it with the desired voltage coming upward. (See Fig. 10)
4)
Replace the plug cover in its original position.
The desired voltage now appears in the plug cover opening. (See Fig. 9)
Figure 9
POWER
TRANSISTOR
REPLACEMENT
The power
transistors used in the output stages are
matched pairs. They have been selected so that they have very
similar current gain and trans-conductance characteristics. This
matching is necessary in order to assure optimum perfor-
mance, but is such that if a transistor fails in either channel,
another transistor in that channel
must
also be replaced.
Transistors are supplied only in matched pairs for replacement.
The transistors diffuse a large amount
of heat which
must
be carried
off in order to prevent damage
to the
transistors the collectors of which are thermally connected to
the heat sink by means
of electrical insulators to avoid
grounding. The insulator is a very thin plastic film mounted
between the transistor case (collector) and the heat sink. A
layer of silicon grease which is a good conductor of heat is
applied to both sides of the insulator in order to improve heat
sink operation. When the power transistors are replaced the
spacer film must be re-installed and a new layer of grease
applied to both sides. Care should be taken, lest conductive
dust such as metal particles should break through the insulator
films. Q401 and Q403,Q402 and Q404 are matched pairs.
=
Figure 10
SCREW___ >
(X3P+10S)
TRANSISTOR
eS
<-— (2SC789©)
SPACER
(AC301)
LUG
(3HW)
SPRING WASHER
(3SW)
NUT
(X3ND)
Figure 11 POWER TRANSISTOR REPLACEMENT
Figure
12 EQUIVA
CIRCUIT
OF INTEGR
CIRCUIT
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