Toshiba TW40F80 manual V Output, Circuit Operation

2-3. V Output

2-3-1. Circuit Operation

The V output circuit consists of a V driver circuit Q302, Pump-up circuit and output circuit Q301, and external circuit components.

(1)Q2 amplifies its input fed from pin 4 of Q301, Q3, Q4 output stage connected in a SEPP amplifies the cur- rent and supplies a sawtooth waveform current to a deflection yoke.

Q3 turns on for first half of the scanning period and allows a positive current to flow into the deflection yoke (Q3 ® DY ® C306 ® R305 ® GND), and Q4 turns on for last half of the scanning period and allows a negative current to flow into the deflection yoke (R305 ® C306 ® DY ® Q4). These operations are shown in Fig. 8-5.

+35V
D301	C308			63V
	D308		V 3	35V
Q301
6	3			GND
	D309	R308	V 7
Q3	7			35V
BIAS			V 2	GND
CIRCUIT	2			63V
Q2
4	Q4	DY
		+
		C306		GND
		R305		Q3 ON
				GND
1
				Q4 ON
	Fig. 8-5

(2)In Fig. 8-6 (a), the power Vcc is expressed as a fixed level, and the positive and negative current flowing into the deflection yoke is a current (d) = current (b) +

(c) in Fig. 8-6, and the emitter voltage of Q3 and Q4 is expressed as (e).

Power Vcc

Q3

i1 Vce 1

Q4

Q2

i2

(a) Basic circuit

(3)Q3 collector loss is i1 x Vce1 and the value is equal to multiplication of Fig. 8-6 (b) and slanted section of Fig. 8-6 (e), and Q4 collector loss is equal to multipli- cation of Fig. 8-6 (c) and dotted section of Fig. 8-6

(e).

GND (b) Q3 Collector current i1

GND (c) Q4 Collector current i2

GND (d) Deflection yoke current i1+i2

Vp

Vcc (e)

1/2 Vcc

GND

Fig. 8-6

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