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PM3394, FLUKE & PHILIPS
ch1
1
ch2
T
ch3
2
ch4
3
CH1!20.0 V=
CH2! 100 V=
CH3!10.0 V=
4
CH4!50.0 V= ALT MTB5.00us- 1.06dv ch2-
Waveform Conv – IC5003 In/Out
Name
Channel 1
Input drive
Channel 2
High drive
Channel 3
Low drive
Channel 4
Output
Time base
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.
STOP
Location
Voltage/div
IC5003/pin 10
12Vp-p
Q5012/gate
160Vp-p
Q5013/gate
12Vp-p
Q5013/drain
150Vp-p
5usec/div
63
+5V @
IC5008/pin
D5041
4
Effects of increased AC line voltage on Converter 2
AC input
100V
3.2V
120V
3V
130V
2.91V
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.
Regulation Effects
PH5003/pin
Oscillator
4
frequency
PH5003/pin 4
Oscillator frequency
56.2kHz
63.54kHz
68.57kHz
+5V
corrective
Output
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