Sony KV-13FS100 Product & Training Manual page 14

IC600 Startup Sequence
1) Turn ON voltage: The 293Vdc from the filter circuit is voltage divided by R630, R629, R627 and R626
down to 2.7Vdc. This voltage is applied to IC600/pin 1 (Vsense) and IC600 turns ON. IC600/pin 1
(Vsense) is also used for OVP protection (IC001/pin 1 > 8 volts will trigger OVP).
2) Internal circuit Start Voltage: The 293Vdc also passes through voltage dropping resistors R615 and
R640, and 291Vdc is applied to IC600/pin 18. This voltage is used to initially power the internal circuits
and begin oscillations. Note that the 293Vdc from R615 is connected directly to the Drain of Q600 and
serves as the High-side FET power source.
Internal circuits initially power by IC600/pin 18
•
Internal drive transistors for High-side output FET Q600.
•
Oscillator
•
Control circuit
•
10V regulator (IC600/pin 10)
Note: The 10V output at IC600/pin 10 passes through D618 and supplies power to the internal
driver transistor for the Low-side output FET Q601
3) Output Oscillations: At this point, initial square-wave oscillations of approximately 125KHz are output at
IC600/ pins 16 and 12. Normal operation frequency is approximately 85KHz.
4) Regulator Feedback: The feedback line is connected to the +135V secondary output. Once IC600 is
turned ON and oscillations begin, the secondary winding at T603/pin 17 and associated circuitry produces
+135. The +135V is applied to Error Amp. IC604/pin 1.
IC604 outputs an error voltage, which controls the current output of the optic-coupler PH602. The amount
of current supplied to IC600/pin 2 depends on how hard PH602 is turned ON. In normal operation, a
voltage of 1.9Vdc (which is proportional to the amount of current) is present at IC600/pin 2. The feedback
loop is now complete.
5) IC600 normal operating power supply (VC1): Produced simultaneously with the oscillator feedback is
the operating power source VC1.
IC600/pin 8 (VC1) is produced using a primary winding on T603/pin 6. The AC is rectified, filtered and a
DC voltage of 24V is applied to IC600/pin 8. Once the 24V is stable, IC600's internal control circuit
disconnects (internally) the power source at IC600/pin 18. All IC600 internal circuits are now powered
from IC600/pin 8.
Over Current Protection (OCP): ref. Figure 3-3
The current flowing through the switching FETS (Q600 & Q601) also passes through R671. The voltage
drop across R671 is directly proportional to the current through the switching FETS. The voltage across
R671 is voltage divided by R647 and R632, and applied to IC600/pin 9. The OCP is activated when the
voltage at IC600/pin 9 exceeds 0.2V. The self-diagnostic indicator will flash four times, pause and then
repeat.
Over Voltage Protection (OVP) and Under Voltage Protection (UVP): The voltage at IC600/pin 8 (VC1) is
monitored by circuitry inside IC600 for Under-voltage and Over-voltage conditions. The two conditions are as
follows:
OVP – greater then 33V
UVP – less then 8V
If either of these two conditions occur at IC600/pin 8, the unit will go into protection mode. The self-diagnostic
indicator will flash four time times, pause and then repeat.
Troubleshooting Tips (ref. Figure 3-3)
NOTE: Follow previously discussed "IC600 Startup Sequence". The five steps are in order of occurrence.
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3.Power Supply Block