Technics SU-Z55 Service Manual

@ CONTENTS
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SAFETY PRECAUTIONS ........-..--2+2 eee ee 2 PRINTED CIRCUIT BOARDS) ...... 2.2.22 ee eeee 7
BEFORE REPAIR AND ADJUSTMENT ......-.-..4.- 2 POWER AMPLIFIER PROTECTION...........-..6. 10
LOCATION OF CONTROLS ........022 22 tee eee 3 FLUORESCENT LEVEL METER .........220005 10
PROTECTION CIRCUITRY ........--2 020 eee eee 3 BLOCK DIAGRAM)... wf ee ee ee 11
DISASSEMBLY INSTRUCTIONS .........2+-2-055 4 SCHMATIC DIAGRAM... 1... ee ee ees 13
RESISTORS & CAPACITORS) ... 1... ee eee ee es 6 REPLACEMENT PARTS LIST ..........2020005 16
EXPLODED VIEW ww Le es 17
Wi SAFETY PRECAUTIONS
. 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.
OfhwWN —
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 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.
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.
lM BEFORE REPAIR AND ADJUSTMENT
1. Turn off the power supply and short-circuit of power supply capacitors ( C406, 6800HF and C407, G800 HF) at
resistance (about 102, 5W) in order to discharge the charged voltage. Do not short between C406 and C407 by
screwdriver. It may damage the componet.
2. Before turning on the power supply after completion of repair, slowly apply the primary voltage by using a power
supply voltage controller to make sure that the consumed current is free of abnormality. The consumed curremt at
60Hz/50Hz in no signal mode is shown below with respect to supply voltage 110V/120V/220V/240V.
Power supply voltage AC110V AC120V AC220V AC240V
200 ~ 400mA 180 ~ 355mA 100 ~ 200mA 90 ~ 180m
Cousumed current
185 ~ 370mA 160 ~ 320mA 95 ~ 190mA 85 ~ 165m

Technics SU-Z55 Specifications

General

Brand	Technics
Model	SU-Z55
Category	Amplifier
Language	English