Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 18
TC5.1U CA
9.
9.
Circuit Descriptions, Abbreviation List, and IC Data Sheets
9.1
Brief Introduction of the Chassis
9.1.1
Chassis block diagram
Figure 9-1 Chassis block diagram
9.1.2
Power Supply Section
This section mainly consists of
•
IC STR-W6735 (IC801).
•
Transformer (T803).
•
Bridge rectifier (DB801).
•
Accessory circuits.
The supply voltage for this chassis should be AC 110V. The
allowed voltage range is 90V to 140V, the frequency range is
50/60Hz.
The AC power with high/low frequency interference goes
through an RC filter, consisting of C801, T801, C802, R801,
and T802. The filter removes the high/low frequency
interference. Then DB801 transforms the AC power to DC
power. T803 and IC 801 work in standby state. T803 will
provide a power voltage to IC101. IC101 scans for the "KEY IN"
signal (Pin 3 of IC101) from the ON/OFF switch on the
keyboard. If "KEY IN" = "power on" signal, pin 64 (IC101) will
generate a signal to drive the photo coupler (IC8021). It acts as
a feed back circuit (feed back to Pin 6 of IC801) for controlling
IC801 to adjust MOSFET.
Transformer T803 provides the following voltages:
•
+13V voltage from Pin16.
•
+130V (B+) voltage from Pin1.
•
+12V from Pin 15.
•
Pin 15 is also connected to two Positive Voltage
Regulators (IC201, IC202) in-series. The outputs of these
regulators are +9V and +5V respectively.
The picture below shows IC201 and IC202:
Figure 9-2 IC 201/202
G_16340_010.eps
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G_16340_022.eps
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