Insulation Resistance Test - Technics SH-8055 Service Manual

Mi SAFETY PRECAUTIONS
AR ONS
. 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
i,
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. B)
Resistance = 3MQ2—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.
lH BLOCK DIAGRAM OF FUNCTION
Tape deck 1 ''playback'"' O———O
Tape deck 2 "'playback"' ote 2 fF
Tape deck 1 ''Rec out"
Tape deck 2 ''Rec out" O
Rch. = (display mode)
Pink noise generator
For detail, refer to Block Diagram on page 28.
Line input O
tape1
Equalizer
(mic attenuator)
—20dB OdB
mic
Mic jack switch
Reh a
Las}, (display
level)
Line output O