Secondary Power Supply; Start Up; Regulation; Testing - Sony KV-32XBR400 Training Manual

Secondary Power Supply

The Primary and Secondary power supplies are similar because they use
the same IC and driver/output stage. They differ in start up and output
voltages.

Start UP

Although IC6501 is identical to IC6001 in the Primary power supply, IC6501/
pin 18 in this supply is not connected to 340Vdc. This makes VC1 at pin
8 the primary source of power to start this IC after pin 1 senses voltage.
The start up sequence is listed as follows:
1. 340Vdc (B+) is applied to this stage from bridge rectifier D6530.
2. Pri Pre 15V voltage from the Primary power supply is applied to IC6501/
pin 8. It must be at least 15.6Vdc to enable IC6501's internal oscilla-
tor.
3. Main Relay signal from Main uCom IC701/pin 72 (HIGH at CN6501/
pin 5) turns ON Q6531, PH6503 and Q6528. Q6528 turns OFF Q6503,
enabling voltage to appear at IC6501/pin 1.
4. R6646 and R6513 deliver at least 1.3Vdc to IC6501/pin 1.
5. IC6501 turns ON using voltage from pin 8 to run the oscillator.
6. An internal diode connected between pin 8 and 10 supplies voltage to
VC2.
7. Oscillator pulses from VC2 pass blocking diode D6502 to make a
("pump up") voltage for the internal predriver amplifier stage.
8. Oscillator signal outputs IC6501/pins 12 and 16.
In summary, these items are necessary to run the Secondary Supply:
Three Items needed to run the Secondary Power Supply
Item
340Vdc (B+) Bridge Rectifier D6530 Powers the Driver/Output
(CN6501/pin 1)
Pri Pre 15V Primary Power Supply
voltage
secondary
(CN6501/pin 5)
Main Relay Main uCom IC701
(normally HIGH
at CN6504/pin 2)
From Purpose
Starts the oscillator when
more than 15.6Vdc.
Enables IC6501 when
HIGH
35

Regulation

The +135V line to the Horizontal Output stage is fed back to IC6501 for
regulation of the secondary power supply. Error Control IC6503 and Optical
Isolator PH6502 control regulation. If the +135V output rises, the voltage
at IC6501/pin 2 lowers to correct. A reduced voltage increases the oscil-
lator frequency and decreases the output voltages of T6501.

Testing

The typical error correction feedback voltage at IC6501/pin 2 is 2Vdc. By
measuring the +135V B+ at R6598 and the feedback at IC6501/pin 2, you
can determine if the problem is in the basic oscillator stage or the error
regulator stage.
1. Measure B+ at
R6598 (0.27 ohms
at 1W)
B+ is LOW or 0V Higher than 2V
Lower than 2Vdc
B+ is HIGH
Higher than 2V
(shutdown Stby
light blinks 3 times)
Lower than 2Vdc
IC V l (P
IC6501 Voltages (Power ON, Video 1 input, Dark screen)
1. 2. 3. 4.
2.5V 1.8V 2.2V 2.5V
10. 11. 12. 13.
10V 0V 4.7V 0 V
Hot ground is at CN6501/pin 6 (black wire).
2. Measure 3. Problem area
IC6501/pin 2
Voltage
Oscillator stage IC6501
Error regulating stage
IC6503/PH6502
Error regulating stage
IC6503/PH6502
Oscillator/Driver Stage
IC6501
ON Vid i D k
5. 6. 7.
0V 0V 4.0V
14. 15. 16.
-15V -19V -19V
)
8. 9.
18.3V 0V
17. 18.
0V 1.5V