1 Safety Precautions
1.1. General Guidelines
1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or
damaged by the short circuit.
2. After servicing, ensure that all the protective devices such as insulation barriers and insulation papers shields are properly
installed.
3. After servicing, check for leakage current checks to prevent from being exposed to shock hazards.
(This “Safety Precaution” is applied only in U.S.A.)
1. Before servicing, unplug the power cord to prevent an electric shock.
2. When replacing parts, use only manufacturer’s recommended components for safety.
3. Check the condition of the power cord. Replace if wear or damage is evident.
4. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc.
5. 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.
1.1.1. Leakage Current Cold Check
1. Unplug the AC cord and connect a jumper between the two prongs on the plug.
2. Using an ohmmeter measure the resistance value, between the jumpered AC plug and each exposed metallic cabinet part on
the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to the
chassis, the reading should be between 1M
Ω
and 5.2M
Ω
.
When the exposed metal does not have a return path to the chassis, the reading must be
.
1.1.2. Leakage Current Hot Check (See Figure 1)
1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check.
2. Connect a 1.5k
Ω
, 10 watts resistor, in parallel with a 0.15µF capacitor, between each exposed metallic part on the set and a
good earth ground such as a water pipe, as shown in Figure 1.
3. Use an AC voltmeter, with 1000 ohms/volt or more sensitivity, to measure the potential across the resistor.
4. Check each exposed metallic part, and measure the voltage at each point.
5. Reverse the AC plug in the AC outlet and repeat each of the above measurements.
6. The potential at any point should not exceed 0.75 volts RMS. A leakage current tester (Simpson Model 229 or equivalent) may
be used to make the hot checks, leakage current must not exceed 1/2 milliamp. Should the measurement is out of the limits
specified, there is a possibility of a shock hazard, and the equipment should be repaired and rechecked before it is returned to
the customer.
Fig. 1
1.2. Before repair and adjustment
Disconnect AC power, discharge Power Capacitors C5101, C5104, C5171, C5172, C5920, C5940 and C5950 through a 10
Ω
, 5W
resistor to ground.
DO NOT SHORT-CIRCUIT DIRECTLY (with a screwdriver blade, for instance), as this may destroy solid state devices.
After repairs are completed, restore power gradually using a variac, to avoid overcurrent.
Current consumption at AC 120V, 60 Hz in NO SIGNAL mode (volume min at CD mode) should be ~ 500mA.
4
SA-AK750P / SA-AK750PC
Summary of Contents for SA-AK750P
Page 8: ...8 SA AK750P SA AK750PC ...
Page 13: ...13 SA AK750P SA AK750PC ...
Page 16: ...With reference to page 13 of the operating instruction manual 16 SA AK750P SA AK750PC ...
Page 18: ...With reference to page 17 of the operating instruction manual 18 SA AK750P SA AK750PC ...
Page 29: ...10 3 Main Parts Location 29 SA AK750P SA AK750PC ...
Page 40: ...10 16 1 Replacement of Pinch Roller and Head Block 40 SA AK750P SA AK750PC ...
Page 47: ...12 4 Checking and Repairing of Power P C B 47 SA AK750P SA AK750PC ...
Page 49: ...Fig 7 49 SA AK750P SA AK750PC ...
Page 53: ...15 2 Power P C B Transformer P C B 15 3 Panel P C B 53 SA AK750P SA AK750PC ...
Page 54: ...15 4 Main P C B 54 SA AK750P SA AK750PC ...
Page 55: ...15 5 XM P C B 15 6 Deck P C B 55 SA AK750P SA AK750PC ...
Page 56: ...15 7 Waveform Chart 56 SA AK750P SA AK750PC ...
Page 58: ...58 SA AK750P SA AK750PC ...
Page 66: ...SA AK750P SA AK750PC 66 ...
Page 68: ...68 SA AK750P SA AK750PC ...
Page 88: ...SA AK750P SA AK750PC 88 ...
Page 93: ...23 Exploded Views 23 1 Cabinet Parts Location SA AK750P SA AK750PC 93 ...
Page 94: ...SA AK750P SA AK750PC 94 ...
Page 95: ...23 2 Deck Mechanism Parts Locations RAA4403 S SA AK750P SA AK750PC 95 ...