Daewoo DSJ-6000LN, Руководство по обслуживанию

Страница: 17 / 39

- 16 -
(3-1) Power Supply for Vin
When Vin Terminal (No.4 pin) voltage that is charged to C821, C830 through the Starting
Resistance reaches 16V(Typ), the Control Circuit inside the F6656 starts to operate. Here,
the Circuit Current is limited to 100 A(MAX) before F6656 operates, so the high Starting
Resistance (47K
,2W) is used. After F6656 operated, the voltage coming out of D
winding of TRANS (T802, T803) is rectified and smoothed, supplying the stable voltage
to the Vin terminal. Here, dl winding is rectified and smoothed via D812, D816, C821,
and C830, and about 16V is supplied to the Vin terminal (No.4 pin) of F6656.
(3-2) OCP/F.B Terminal (Oscillator, Electrostatic Voltage Control Circuit)
Inside the F6656, there is the Oscillator that generates Pulse signal for controlling
electrostatic voltage in the secondary side by turning ON/OFF the MOSFET using the
charging/discharging of C . When AC input is high or Load Current is low, the inflow of
the current of F/B terminal increases, and ON time decreases. The Oscillator has the
Transient Current Protection Circuit (O.C.P. circuit) of Pulse by Pulse type that controls
the oscillator s output by detecting MOSFET Drain current s peak value per every pulse.
(3-3) D/S Terminal (Driver Circuit)
This Circuit is the circuit that charges/discharges the capacity between Gate-Sources of
Power MOSFET by receiving Pulse signal.
(3-4) Latch Circuit
This Circuit is the circuit that stops Power Circuit by keeping the output of the Oscillator
to LOW when the Over Voltage Protection Circuit (OVP) and Overheat Protection Circuit
(TSD) operate. The Sustaining Current of the Latch Circuit is 400 A(MAX) when Vin
terminal voltage is 8.5V, so if the current over 400 A is made to flow to the Vin terminal,
the Power Circuit keeps normal. This circuit activates the Latch Circuit only when OVP,
TSD Circuit operates or when external signal input is kept over 10 sec, by setting the
delay time in accordance with C inside F6656 in order to prevent erroneous operation
due to Noise, etc. Besides, even though Latch Circuit operates, it is operated in
electrostatic power circuit in the Control Circuit so the Circuit Current gets elevated,
decreasing the Vin terminal voltage dramatically. When Vin terminal voltage gets below
Termination Voltage (10V TYP), the Circuit Current increases again, so Vin terminal
oltage decreases. That is, Vin terminal voltage increases or decreases between 10V and 6V
when Latch Circuit operates, it is possible to prevent Vin terminal voltage rising
bnormally. To cancel the Latch Circuit, Vin terminal voltage should be decreased to below
6.5V. Generally, it can be cancelled by turning off the AC power.
(3-5) Overheat Protection Circuit (TSD)
This Circuit is the circuit that operates the Latch Circuit when the Frame
temperature exceeds 150 degrees (TYP). In this circuit, the real temperature detection is