Technics RS-B105 Service Manual page 3

RS-B105 RS-B105
& SAFETY PRECAUTION (This "safety precaution" is applied only in U.S.A.)
OP WNHN >
. Before servicing, unplug the power cord to prevent an electric shock.
. When replacing parts, use only manufacturer's recommended components for safety.
. Check the condition of the power cord. Replace if wear or damage is evident.
. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc.
. Before returning the serviced equipment to the customer, be sure to make the following insulation resistance test to
prevent the customer from being exposed to a shock hazard.
e INSULATION RESISTANCE TEST
1.
2.
3:
Unplug the power cord and short the two prongs of the plug with a jumper wire.
Turn on the power switch.
Measure the resistance value with ohmmeter between the jumpered AC plug and each exposed metal cabinet part, such as
screwheads antenna, control shafts, handle brackets, etc. Equipment with antenna terminals should read between 3MQ
and 5.2MQ to all exposed parts. (Fig. A) Equipment without antenna terminals should read approximately infinity to
all exposed parts. (Fig. B)
Note: Some exposed parts may be isolated from the chassis by design. These will read infinity.
4.
Antenna
terminal
Exposed Exposed
metal metal
part part
Ohmmeter Ohmmeter
(Fig. A) (Fig. 8)
Resistance = 3MQ—5.2MQ Resistance = Approx oo
If the measurement is outside the specified limits, there is a possibility of a shock hazard. The equipment should be
repaired and rechecked before it is returned to the customer.
@ OPERATION
Dolby noise-reduction system
Noise-reduction systems are designed to reduce the annoying
characteristic "hiss" noise during playback by recording on
systems
the tape by the noise-reduction system.
When the recording is made, the level of high frequency
signals is raised, and then this level is lowered during
playback, thus effectively reducing high-frequency noise and
Dolby B system
the conventional Dolby noise-reduction system.
expanding the dynamic range.
This unit uses the Dolby B-type of noise-reduction systems.
¢ The B-type Dolby noise-reduction performs this function in
the high frequency range.
M@ Examples of uses of the noise-reduction
Use this system for playback of tapes which were recorded by
m@ DISASSEMBLY INSTRUCTIONS
How to remove the cabinet a How to remove the mechanism unit
Procedure Procedure
1>2
1. Push the eject button (see fig. 1).
2. Remove the 4 screws (@~@).
3. Remove the counter belt.
«Remove the 4 screws (@~@).
Cabinet
1.Remove the 2 screws (@, @).
2.Remove the 4 tabs aside.
Front Panel
1. Remove the 2 screws (@, @).
2. Pull out the volume knob.
Procedure
1-3
: Volume P.C.B.
Fig. 3 Fig. 4
How to remove the front panel ae How to remove the main P.C.B.
co. be 1. Remove the 2 screws (@, @).
2. Open the 2 tabs aside, and then
pull down the back chassis.
Back chassis
0
g Serial Number
Plate
Procedure
1-2-3
4-5
* Serial No. Indication
¢ The serial number plate of this product is attached to the back chassis (shown in fig. 6).
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