Yamaha PSR-S770, Service Manual

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59
PSR-S770/PSR-S970
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PSR-S770■DMM■CIRCUIT■BOARD■CHECK■METHOD
The DMM Circuit Board is provided with test points for service check purposes.
Check the test points on the DMM Circuit Board if the following symptoms appear.
Symptoms and check items
(1) No LCD display with Power SW ON --> Check items ① to ⑦ sequentially.
(2) No sound or distorted sound --> Check items ① , ⑧ to ⑬ sequentially and OUTPUT check items.
Test■Point
NO. Test Point Circuit Judgment criteria Measured by Parts with possible defects
① PV
Power supply
for Power amplifier IC
More than 14.0V Multimeter
TH100 or FT100
(On AJACK circuit board)
② 16V
Power supply
for digital circuit
More than 14.0V Multimeter
TH100 or FT100
(On AJACK circuit board)
③ +5D 5V power for digital circuit 5.0V±0.5V Multimeter IC810
④ +3.3D 3.3V power for digital circuit 3.3V±0.3V Multimeter IC810
⑤ +1.3D 1.3V power for CPU 1.3V±0.1V Multimeter IC209
⑥ +1.0D 1.0V power for TG 1.0V±0.1V Multimeter IC606
⑦ RESET CPU & memory reset signal 3.3V±0.3V Multimeter IC004
⑧ 12A 12V power for analog circuit 12V±1V Multimeter
IC100
(On AJACK circuit board)
⑨ 5A 5V power for analog circuit 5.0V±0.5V Multimeter IC811
⑩ OUTL AUX output L channel
There shall be audio output
without distortion.
Signal Checker IC801 or IC807
⑪ OUTR AUX output R channel
There shall be audio output
without distortion.
Signal Checker IC801 or IC807
⑫
HPL HP output L channel
There shall be audio output
without distortion.
Signal Checker IC800 or IC807
⑬ HPR HP output R channel
There shall be audio output
without distortion.
Signal Checker IC800 or IC807
Note1: Use the standard AC adapter PA-300C for check operation.
Output■states
NO. SPEAKER PHONES OUTPUT Parts with possible defects
1 × × ×
IC001, IC002, IC007 or CPU Error
Detect Circuit
2 × ○ ○ IC802, SP-/MUTE Signal or HP JACK
3 ○ × × IC807 or IC805
4 ○ × ○
IC800, TR800 or
RY200 (On HP circuit board)
5 ○ ○ ×
IC801 or
TR103-TR106 (On AJACK circuit board)
Note: “ ○ ” mark expresses normalcy and “ × ” mark expresses a failed state.