15. Precautions before Servicing
15.1. Precautions for measuring of the output waveforms
1. The waveform was measured with a “National Digital Storage
Oscilloscope VP-5730A”. Therefore the waveforms of musical tone
signals shown may differ somewhat due to the difference in the
timing of triggering.
2. Since the 1/10 test probe is used, the indicated voltage value on
the bottom part of each waveform illustration is 1/10 of the actual
value (e.g. 0.2 V/cm should be 2.0 V/cm).
3. To measure the waveforms, first set this unit to the service
diagnostic mode (refer to “WAVE ROM test ”). The WAVE ROM
output will then be output as a sine wave to facilitate the
servicingcheck.
15.2. Important safety notice
- Components identified by a mark have special characteristics
impotant for safety.
- When replacing any of these components, use only manufacture’s
specified parts.
15.3. Symbolic Marks
The symbolic marks for resistors and capacitors which used in this circuits are classified as
following Table-1 and Table-2 .
15.3.1. RESISTORS
- Resistors without symbolic mark are FIXED CARBON FILM
RESISTORS (ERD-type).
- All resistors are 1/4 WATT, ±5 % TOLERANCE unless otherwise
designated in schematic diagrams.
Table-1
27
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