Yamaha T3n Service Manual page 56

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T5n/T4n/T3n
3-2 Repair Flowchart
Check the primary side circuit.
Note: Check and repair must be done carefully, otherwise the electrical shock may be caused.
Discharge
1 Check R129, R172 and R174 resistor value.
2 Check Q106 and Q107 C-E resistance.
3 Check Q113 and Q114 C-E resistance.
4 Check R140, R141, R142 and R143
resistor value.
5 Check R138 and R139 resistor value.
6 Check R166 and R167 resistor value.
(Secondary)
56
START
Turn the power switch off.
(Disconnect AC plug from the wall outlet.)
• Between ± terminals of C124 and C125
• Between ± terminals of C126 and C127
• Between CN105 – CN107
• Between CN108 – CN110
• Between terminals of C10
R129, R172, R174 = 6.8 ohms ?
YES
Q106, Q107 C-E
Resistance = 0 to several
ohms ?
NO
Q113, Q114 C-E
Resistance = 0 to several
ohms ?
NO
R140, R141, R142, R143 =
10 ohms ?
YES
R138, R139 = 4.7 ohms ?
YES
R166, R167 = 2.2 ohms ?
YES
A
CAUTION:
To prevent the electrical shock, be sure to discharge
electricity from the capacitor.
Discharge is not necessary if you have left the unit
for 10 minutes or more after turning the power off.
NO
Replace R129, R172 and R174.
YES
Replace Q106 and Q107.
Replace IC103.
YES
Replace Q113 and Q114.
Replace IC104.
NO
Replace R140, R141, R142
and R143.
NO
Replace R138 and R139.
NO
Replace R166 and R167.
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