Toshiba TDP-TW100B, Service Manual

Page: 52 / 90

Chpater 6
6–20
d) Over Voltage Limit
Output voltage is detected by winding voltage of Bl-82 (T101).This voltage is same as Vcc of IC101
(pin6).If output voltage becomes over voltage condition, pin 8 of IC101 to be pulled up
through zener diode ZD102,then power supply is shut down.
e) Over Heat Protection
Over heat protection is detected Soldering parts temperature of Ql,Q2(MC102)
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 downed.
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 method, and 3.4V output is controlled by this method.
Charged primary energy is sent to secondary by transformer T101.Normal1y, 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 and C207 which smooth out the pulsation to
give a low ripple DC output.L201 and C210 are LC filter, which reduce ripple voltage.