Circuit Description Of Teuliu Pwb - Sharp UX-2200CM Service Manual

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FD-215OCMu/CMc
[3] Circuit description of TEULIU PWB
(1) TEL/LlU block operational description
1) Block
diagram
Fig. 6
3)
Block description
1. Surge Protection circuit
This circuit protects the circuit from the surge voltage occurring on the
t818phOn8 line.
l
The AR1 protects the circuit from the 390V or higher line StQ8
voltages.
l
The VA1 and VA2 protect the circuit from the 470V or higher VeIti-
cal surge voltages.
2) Circuit description
The TEULIU PWB is composed of the following 10 blocks.
1. Surge protection circuit
2. On-hook status detection circuit
3. Dial pulse generation circuit
4. CMLrelay
5. Matching transfomer
6. Hybrid circuit
7. Signal selection
8. Sensor circuit
9. Cl detection circuit
10. Power supply and bias circuit
5-11