Sony DTV-01, Manual

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63
P M 3 3 9 4 , F L U K E & P H I L I P S
ch4
ch3
ch2
ch1
CH1!20.0 V=
CH2! 100 V=
CH3!10.0 V= STOP
CH4!50.0 V= ALT MTB5.00us- 1.06dv ch2-
1
2
3
4
T
Waveform Conv – IC5003 In/Out
Name Location Voltage/div
Channel 1 Input drive IC5003/pin 10 12Vp-p
Channel 2 High drive Q5012/gate 160Vp-p
Channel 3 Low drive Q5013/gate 12Vp-p
Channel 4 Output Q5013/drain 150Vp-p
Time base 5usec/div
Regulation
+5V is returned to the oscillator stage for regulation. The +5V output is
applied to error regulator IC5008/pin 1. Internally the +5V input is com-
pared to a reference and its difference (error) is output from IC5008/pin 4
to PH5003/pin 2. This photocoupler couples the error voltage signal from
the cold to hot ground into IC5004/pins 1 and 6.
At IC5004, an increase in control voltage results in a decrease in oscillator
frequency. The oscillator signal is amplified by IC5003, Q5012, and Q5013
and is applied to a LC circuit consisting mainly of C5040/T5003. The
oscillator frequency is positioned above (higher than) the resonate fre-
quency of C5040/T5003. Therefore, an increase in the oscillating frequency
results in a reduced output from the T5003 transformer (L). Conversely, a
decrease in oscillator frequency results in a higher secondary voltage.
Regulation Effects
+5V @
D5041
IC5008/pin
4
PH5003/pin
4
Oscillator
frequency
+5V
corrective
Output
Effects of increased AC line voltage on Converter 2
AC input PH5003/pin 4 Oscillator frequency
100V 3.2V 56.2kHz
120V 3V 63.54kHz
130V 2.91V 68.57kHz
Power OFF Detector
Q5015, Q5010, Q5011 and D5021 are the major parts that comprise the
power off detector. When the AC relay is turned OFF, this circuit detects
a loss of +164V and grounds PH5003/pin 4. This increases the oscillator
frequency, which decreases the Converter 2 output voltages during power
loss. The connection to Converter 1 from this stage performs the same
function, but is not shown.