Technics SU-A80 - Safety Precautions; Insulation Resistance Test

Mi CONTENTS
Page Page
SAFETY::PRECAUTION®. .. ai. ee Se ee ee ae 2 SERVICING PARTS FOR EQUALIZER
LOCATION OF CONTROLS ..............-0--0- 3 DIFFERENTIAL TRANSISTORS (Q101 ~ Q108).... 13
RECORDING ois. 5: oie aes Gag nS Be aw ee wha 4 BLOCK DIAGRAM ........ 2... 2. cece ee eee 14,15
DISASSEMBLY INSTRUCTIONS. ................. 5 SCHEMATIC DIAGRAM ...............-0.205 16 ~ 21
ADJUSTMENT PROCEDURE................+2.. 6 RESISTORS & CAPACITORS ...........-..2.008. 22
PRINTED CIRCUIT BOARDS ................ 11 REPLACEMENT PARTS LIST ................04. 23
WIRING CONNECTION DIAGRAM ............. 11,12 EXPLODED VIEWS... jibe ieee eee ea neas 24,25
BASIC OPERATION OF INPUT SELECTOR
CONTROL CIRCUIT...................2-. 13
li SAFETY PRECAUTION
. 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.
arPWN —
e INSULATION RESISTANCE TEST
1. Unplug the power cord and short the two prongs of the plug with a jumper wire.
2. Turn on the power switch.
3. 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 3M{Q2
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.
Antenna
terminal
Exposed Exposed
metal metal
part part
Ohmmeter Ohmmeter
(Fig. A) (Fig. B)
Resistance
=
3M2—5.2MQ
Resistance
=
Approx
oo
4. 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.