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14.
TROUBLESHOOTING
TROUBLE
FAULTY
BLOCK
CHECKPOINT
No Power
Power Circuit
Checkpoints' voltages in accordance
with the schematic diagram
Power Switch
Switch contacts and switch spring
tension
Reset Circuit
Waveform (1)
Power ON Detector
Waveform Q)
CPU (MSM6293)
|
Pulse Generator
Waveform ©
ROM (uPD23C256EAC)
No sound at all
Power Circuit
Voltages VA, VX .
Reset Circuit
i
Е
Waveform
0
Pulse Generator -
|
Waveform (3)
CPU (MSM6293)
|
ROM (uPD23C256E AC)
|
I
Mixing Amp.
Emitter of transistor T11
|
Power Amp. (LA4138)
Pin2
Speaker
Speaker terminal (red wire)
ET
|
д
No melody, chord, bass, and
CA91A02
obbligato (percussion sounds)
| Filter
Emitters of T14 and T15
CPU (М5М6293)
No chord, bass, and obbligato
CA91A02
Gain Controller
Pin 11 of TC4066
CPU (uPD23C256EAC)
ROM (uPD23C256EAC)
No percussions
Percussion Generator (MSM6294)
Pin 19
Clock Pulse Generator
Waveform (4) i
Percussion Filter
Emitter of T12
CPU (М5М6293)
ROM (uPD23C256EAC)
Demo music cannot be played
Demo Music ROM (MSM5268)
RAM (uPD43256C)
CPU (MSM6293)
ROM (uPD23C256EAC)
|
Certain keys or switches do
not respond
1
Dirty contacts
Sampling impossible
Microphone
E
Sampling Circuit
Collectors of T28 and T29
CPU (MSM6293)
RAM (uPD43256C)
= 18—
pe.
е -----
3
μπας
| T TT T T
0| 0 0 0 0 0 μ η η
τ a ˆ
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