Sony DTV-01, Руководство пользователя

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123
P M 3 3 9 4 , F L U K E & P H I L I P S
c h 4
c h 3
c h 2
c h 1
C H 1 ! 5 . 0 0 V =
C H 2 ! 2 . 0 0 V =
C H 3 ! 1 0 . 0 V =
C H 4 ! 1 2 2 V = C H P M T B 1 0 . 0 u s c h 1 +
1
2
3
4
T
Power MOSET D
TO 220 case
P or N channel
G D S
Summary
The following waveforms show the operation of the entire stage from pulse
manufacture (ch 2), through inversion (ch 3), to the final dynamic focus
signal at Q7012/drain (ch 4). Note that the width of the final dynamic focus
signal at Q7012’s drain (ch 3) is now extended beyond the horizontal re-
trace interval.
This is a normal and planned characteristic of the resonate output stage
consisting of T7001, C7040 and C7023. When Q7012 is off, the output
stage rings at the resonate frequency. However, when Q7012 is on, L7004
and L7005 are added to the tank circuit, lowering the frequency. The re-
sult is that the negative portion of the resonate sine wave is longer than the
top. The longer negative portion keeps the pulse at Q7012/drain low for a
longer period than the input gate signal. This is why the drain signal is
extended beyond the horizontal retrace interval.
The output pulse width (ch 3) extends beyond the FBT retrace interval (ch
1) to mark the left side of the TV screen for focus correction. This means
the final dynamic focus correction signal (Q7012/drain) starts before the
FBT retrace signal and ends after it. This corresponds to the left and right
side of the TV picture where dynamic focus correction is needed. This
signal is coupled by DFT T7001/pin 4 to the static focus voltage (FBT
T7002/pin 16) for dynamic focus correction.
W a v e f o r m D F g - S i g n a l A m p l if ic a t i o n
N a m e L o c a t io n V o lt a g e / d iv
C h a n n e l 1 F B T s i g n a l F B T N / A
C h a n n e l 2 D e la y e d . p u ls e I C 1 5 0 2 / p in 2 1 . 4 V p - p
C h a n n e l 3 D F - D r i v e C N 1 3 0 3 / p i n 3 1 2 V p - p
C h a n n e l 4 D y n a m i c f o c u s
s i g n a l Q 7 0 1 2 / d r a in 1 7 8 V p - p
( N o r m )
2 7 3 V p - p ( w i d e )
T i m e b a s e 1 0 u s e c / d iv
Static MOSFET Resistance Tests
S ta t ic M O S F E T R e s is t a n c e T e s ts
+ / - - / +
G a te – S o u r c e I n fin it y I n fin it y
G a te - D r a in I n fin it y I n fin it y
D r a in - S o u r c e T h e r e is a z e n e r d io d e c o n n e c t e d in te r n a lly
a c r o s s t h e s e te r m in a ls
Operational test
To prove the device is functional:
1. Connect the negative lead of the ohmmeter to the SOURCE lead.
2. Touch the ohmmeter positive lead to the gate to pre-charge it.
3. Connect the ohmmeter positive lead to the DRAIN.
If the device is good you will get a resistance reading of about 400-1k
ohms.