Toshiba 13A21 Service Manual page 42

D2005(zener diode) connect
between 12V and SCR2001, if
Power 12V voltage over 16.42V typ.
supply (16.05~16.79V) the SCR will
OVP turn on then cut off the VCC of
power IC cause power supply
shutdown.
The power IC(IC1001, IC1003,
IC1005) have a input pin for
Power
current sense function, the
supply
current sense function are for
short circuit
error amplifier feedback loop
protection
and short circuit protection
function.
Thermal
protection
TH1: 100~110 degree C (105
function on
degree C typ)
ballast
board
Over
voltage
VL=150V(typ), range
protection
140V~160V; VL=220V(typ)
function on
LPS mode.
ballast
board
Short
circuit
protection
VL<10V
function on
ballast
board
Normal 12V output
Condition <16.42V (typ)
Abnormal 12V output
condition >16.42V(typ)
Transformer
Normal secondary
Condition components are
no failure.
Any transformer
secondary
Abnormal components are
condition failure (winding,
diode,
capacitor).
Normal <105 degree C
Condition (typical)
Abnormal >105 degree
condition C(typical)
Normal
<150V(typ)
Condition
Abnormal
>150V(typ)
condition
Normal
>10V
Condition
Abnormal
VL<10V
condition
42
Power IC no VCC, Power supply
shutdown immediately.
(12V-->D2005 (zener diode)
/R2018/D2006-->SCR2001-->D201
4/IC2004 (photo coupler)-->Q1006/
Q1005 (VCC control for Power ICs
IC1001/IC1002/IC1005); SCR hold
up current:
5VSB-->Q2004-->R2043-->SCR20
01.
Power supply into to protection
state. (Power IC detect the current
sense voltage at each re-start up
cycle, and will auto recovery
immediately after the short circuit
condition remove)
Ballast shutdown.
Ballast shutdown.
Ballast shutdown.
AC off/on to re-start
up (AC off-->5VSB
off-->SCR2001 off)
AC off-->remove
short circuit-->AC on
AC off --> Check fan
status --> AC on