TC- 446 Service Manual
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40
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VI. Power Supply
:
Fail to power on (no response while rotating power knob after plugging in power supply)
N
Y
Plug positive end of power cable into
positive connector while negative end
into aluminum chassis or ground
around PCB;
Turn off radio; 6.0V
output at L15
Upper
?
Check L15, C149,
C120; Replace faulty
components.
Switch on power;
6.0V at IC4 IN?
Check power switch,
D20, IC4; Replace
faulty components.
5V at IC4
OUT?
Check if short circuit
occurs when IC4, C80,
C79, branch circuit are
grounded; Replace
faulty components.
Check IC11 pin 71/ 72;
5V at IC9 pin 5 (RESET)?
Check if no-solder at
IC11 and branch
components; Replace
faulty components.
Start
Check IC11, X3 (7.3728
MHz crystal), peripheral
R&C; Replace faulty
components;
Y
N
N
N
Y
Y
Содержание TC-446
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