Yamaha T3n Service Manual page 57

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7 Check the AC voltage between
the test point B and C.
8 Check the waveform.
Remove F101 and F102.
Turn the power switch on.
Test point B – C
AC voltage = power supply
voltage ?
Note: Do not connect the oscilloscope chassis with the chassis of this unit when checking the waveform.
When measuring the waveform, short-circuited the PR101.
Check the waveform between pin 1 (LO) and pin 2 (COM) of IC103
Waveform check OK ?
Note: Do not connect the oscilloscope chassis with the chassis of this unit when checking the waveform.
When measuring the waveform, short-circuited the PR102.
Check the waveform between pin 1 (LO) and pin 2 (COM) of IC104
A
NO
YES
B
NO
YES
B
C B
D
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Replace PST circuit board.
Check the square wave.
• Period: approx. 14.3 µS (approx. 70kHz)
• Amplitude: approx. 15 Vp-p
Test point
12 pin of IC101 – D DC voltage =
approx. +16 V ?
YES
Replace IC103.
If IC103 has been replaced, replace IC101.
Check the square wave.
• Period: approx. 14.3 µS (approx. 70kHz)
• Amplitude: approx. 15 Vp-p
T5n/T4n/T3n
NO
57