Note For Printed Wiring Boards And Schematic Diagrams - Sony SPP-935 Service Manual

5-3. NOTE FOR PRINTED WIRING BOARDS AND SCHEMATIC DIAGRAMS

Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ω and
1 / W or less unless otherwise
4
specified.
• 2 : nonflammable resistor.
• 4 : micro-strip line.
• C : panel designation.
Note: The components identified by mark ! or dotted line
with mark ! are critical for safety.
Replace only with part number specified.
• U : B+ Line.
• Power voltage is dc 9 V and fed with regulated dc power
supply from external power voltage jack (J8).
• Power voltage is dc 12 V and fed with regulated dc power
supply from modular jack (J7).
• Voltages and waveforms are dc with respect to ground in
test mode.
• Voltages are taken with a VOM (Input impedance 10 MΩ).
Voltage variations may be noted due to normal produc-
tion tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
• Circled numbers refer to waveforms.
• Signal path.
N
: RX (TELEPHONE)
O
: TX (TELEPHONE)
F
: RX (INTERCOM)
f
: TX (INTERCOM)
P
: bell
Note on Printed Wiring Boards:
• X : parts extracted from the component side.
• Y : parts extracted from the conductor side.
• : Through hole.
r
• b : Pattern from the side which enables seeing.
(The other layers' patterns are not indicated.)
Caution:
Pattern face side: Parts on the pattern face side seen from
(Side B) the pattern face are indicated.
Parts face side: Parts on the parts face side seen from
(Side A) the parts face are indicated.
– 23 –
• Waveforms
– BASE UNIT Section –
1 U2 !¡ (XIN)
550 m Vp-p
30.8 ms
2 U3 #¶ (OSC1)
6.6 Vp-p
250 ns
3 U17 6 (OSC_IN)
(Press dial button at dial signal is tone)
1.7 Vp-p
280 ns
– HANDSET Section –
1 U2 !¡ (XIN)
340 m Vp-p
250 ns
2 U3 #¶ (OSC1)
3.8 Vp-p
250 ns
– 24 –