Toshiba TDP-TW300U Service Manual page 59

d) Over Voltage Limit
Output voltage is detected by winding voltage of B1-B2 (T101). This voltage is same as Vcc of IC101
(pin 6).
If output voltage becomes over voltage condition, pin 8 of IC102 to be pulled up through zener diode
ZD102, then power supply is shut down .
e) Over Heat Protection
Over heat protection is detected Heatsink temperature of Q102,Q103,Q104,D103,Q108 by TH102
and temperature of winding of T101 by thermo-fuse.
At abnormal condition (ex. Over-load or fan-lock ) when over temperature from setting temperature,
power supply shall be shut down.
The thermo-fuse becomes open in order to protect other parts.
5) Secondary rectifier circuit
The cathode voltage of D203 is pulsating. D203 and C211, which smooth out the pulsation to give a low
ripple DC output.
6) Time Sharing Multi-output Control Circuit
This is one of output control methods, and 3.4V output is controlled by this method.
Charged primary energy is sent to secondary by transformer T101. Normally, one winding power is used
for one output only.
But this circuit is added the switching device (D204 and Q202) on secondary, it controls switch timing for
sharing primary power by MC201.
The voltage of Q202 source is pulsating. D204,Q202,C207 and C216 which smooth out the pulsation to
give a low ripple DC output. L201 and C210 are LC filter, which reduce ripple voltage.
6-27
Chapter 6