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33
Troubleshooting
BMX board Side A
Troubleshooting Reference
8
13
19
23
24
R7739
R7736
R7736
R7739
R7738
R7738
5
IC775
1
Reference B
34
Troubleshooting
3-3-3. Main Board Power On Checking (for Main SP Lch & Rch) for BMX board only
No
Checking Item
OK
NG
If NG
If NG
1
Check
IC7751 side-terminal of
L7751,L7752,
L7753,L7754
Switching Freq = 384kHz or 768KHz
±20KHz
Vrms = don’t care
No switching
frequency at
either one of the
CL
Go to next checking.
2
Check F7751 MainSP
(for BMX XM-H board
only)
V(before fuse) = 12.5V ± 0.5V
V(after fuse) = 12.5V ± 0.5 V
No voltage.
Check fuse broken?
Check CN9000 Pin 16
&18 got 12.5V?
Change fuse (5A).
Check power supply
board audio VCC.
3
Check F7751 MainSP
(for BMX XM-A, XM-AT
and XM-DT only)
V(before fuse) = 19.5V ± 0.5V
V(after fuse) = 19.5V ± 0.5V
No voltage.
Check fuse broken?
Check CN9000 Pin 16
&18 got 19.5V?
Change fuse (5A).
Check power supply
board audio VCC.
4
Check IC7751 (Pin 5) at
R7879
(for BMX board only)
V(before R7879) = 3.3V ± 0.5V
V(after R7879) = 3.3V ± 0.5V
No voltage.
Check +3.3V_MAIN
supply.
5
Check R7876, R7877,
R7878
Vdc = 3.3V ± 0.3V
Vdc < 0.8V
R7877 NG,
Check IC7751
R7876, R7878 NG,
Check IC1000
6
Check R7736, R7738,
R7739, and R7740
R7738 = 12.288MHz
R7740 = 3.072MHz
R7739 = 48KHz
R7736 = moving CLK
All Vp-p ≈ 3.3V
If no frequency at
R7738, R7739,
and R7740,
Muffin IC
(IC1000) NG.
If no frequency
at R7736 make
sure sound
source OK.
If sound source OK, but
at R7736 = NG, Muffin IC
(IC1000) NG.
Note : Parts location refer BMX Board : Reference A and Reference B.
35
Troubleshooting
No Sound
HP / Lineout only
BMX Power On checking
This is for Main SP got sound, but HP / Lineout no
sound
3-3-4. No Sound: HP / Lineout Only for BMX board only
No
Checking Item
OK
NG
If NG
1
Insert HP Jack. Check R7705
Vdc = 3.3V ± 0.3V
Vdc = 0V or < 1V
Check HP_DET line
(R7705 – for BMX)
got short to GND? If short to GND
replace board
.
2
Check IC7701 Pin 5
(X_AUDIO_MUTE_ SPHP)
Vdc = 3.3V ± 0.3V
Vdc = 0V or < 1V
Check X_AUDIO_ MUTE_ SPHP
(Pin 5) short to GND. If short to
GND replace board.
3
Check JL7701 and JL7702.
(with audio signal input)
Can see audio signal
waveform
Cannot see audio signal
waveform
Go to below item No. 4 for
checking
4
Check IC7701 pin 9
Vdc = 3.3V ± 0.3V
No 3.3V supply.
5
Check R7707, R7708
(with audio signal input)
Can see audio signal
waveform
Cannot see audio signal
waveform
Muffin IC (IC1000) NG
GN1 Main Board Power On Checking
36
Troubleshooting
3-3-4. No Sound: HP / Lineout Only for BMX board only
BMX board Side A
Troubleshooting Reference
IC7701
5
9
R7707
R7708
6
7
8
1
14
C7702
R7705
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