Converter Voltage Outputs - Sony CTV-25R1 Manual

Converter Voltage Outputs

Once the converter oscillator is running, current is induced into the sec-
ondary windings to power the set. Three voltages are derived from this
converter power supply:
· Audio Vcc = +13Vdc
· B+
· +12 Vdc Source
Audio Vcc
This fused +13Vdc is applied to power amplifier ICs. The 27" TV uses
one stereo power amplifier IC because all the 27" TVs are stereo.
Audio Vcc Destination
TV Type Audio Output Package 1
13" and 20" Monaural IC400
13" and 20" Stereo IC400 (right)
27" IC401 (stereo pkg)
B+
Two different T603 Power Input Transformers are used:
Power Input Transformers (USA models)
TV Type T603 part number
13" & 20" 1-431-674-11
27" 1-431-837-11
D610 is a 150Vdc-zener diode placed on the B+ line to guard against
excessive B+ voltage. D610 will short to prevent the horizontal output
transistor and transformer load from seeing the excessive B+ voltage.
Unfortunately, a prolonged short on the B+ line will load down the con-
verter stage. In the converter stage, IC601 will short (fail) trying to supply
current to maintain the B+ voltage. Therefore if you find a shorted con-
verter IC601, check the D610 zener as well. After parts replacement,
test the converter stage by following the steps outlined in the Converter
section of this book.
Audio Output Package 2
IC401 (left)
B+ Voltage Output
115-116Vdc
135Vdc
29
+12 Vdc Source
+12Vdc is applied to several stages at plug in
Stage
Q604, Q605, switched +9V
regulator.
RY601, Degaussing Relay.
Q203, Audio mute.
IC002, Standby +5Volt regulator.
IC001 Vcc Power
At plug in, Micro IC001 is powered and reset using IC002. When +12Vdc
is applied to IC002/pin 4, a regulated +5Vdc leaves pin 5. This is the
Standby +5Vdc used to power the Micro IC001, Memory IC003, and the
remote infrared receiver IC004.
IC001 Reset
IC001 also needs to be reset when standby power is applied. IC001/pin
30 is connected to IC002/pin 2. IC002 performs the reset operation by
keeping its pin 2 LOW for 60msec at AC plug in. After 60 msec., reset
ends when this line goes HIGH. The HIGH permits the Micro to operate
beginning with memory data retrieval.
This reset operation is shown in the following waveforms. The top chan-
nel 1 is the standby +5Vdc at plug in. The middle waveform is the reset
signal from IC002 and the bottom waveform (channel 3) is the reset sig-
nal at IC001/pin 30 after a pi-filter network. The pi-filter network insures
no voltage spikes pass into the Micro.
Plug Into 120Volts AC
Channel 1 – IC002/pin 5; 2V/div.
Channel 2 – IC002/pin 2; 2V/div.
Channel 3 – IC001/pin 30; 2V/div.
Time Base = 20msec/div.
Capacitor C690 connected to IC002/pin 3 is used to extend the reset
time to 60msec. Without it, the reset time is only 20msec.
Purpose
Applies +9Vdc to the Jungle IC to power ON
the TV.
Permits the degaussing relay to operate at plug
in (TV power is OFF).
Insures audio mute at power OFF.
Powers and resets Micro IC001.
See below.