Sony DTV-01 Manual Download

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D Board Protection Block

Protection

The protection circuitry on the G and D boards monitor the following items
and shuts the TV off if there is a problem:

G Board:

Vertical deflection loss (self diagnostics - light indication)

+5V OCP monitored (self diagnostics - light indication)

+5V OVP monitored (self diagnostics - light indication)

+135V OCP monitored (self diagnostics - light indication)

+135V OVP monitored (self diagnostics - light indication)

+15V OVP

Surge relay RY5502 not energized.

D Board:

Driver supply voltage OVP

H. Output OVP

H. Output OCP

FBT Output OVP

H Centering IC4003 OCP

Horizontal Drive Signal Flow

The D board contains power handling deflection components. The H
drive signal is amplified by the horizontal driver, Q4011 and Q4018 output
devices on this board. The resultant output signal is used to develop
flyback voltages and yoke deflection current. Major power handling cir-
cuits on the D board are monitored for excessive voltage or/and current.
TV shutdown will occur if there is a danger of this.

Driver supply voltage OVP

H. Output OVP

Both the driver and output devices (Q4011 and Q4018) need B+. The B+
is supplied and regulated by PWM circuits, Q4003 & Q4022. The voltage
from both of these PWM stages is monitored by over voltage protection
sensing circuits (OVP) and connected via D4003 and D4060 to the shut-
down latch located on the G board.

H. Output OCP

The current to the H. output and centering stages is also monitored by the
protection sensing circuits on the D board. Q7003 watches the current
flowing from the +135V supply through the following sections before arriv-
ing at the Horizontal Output device, Q4018:

+135V – source voltage from converter 1

Q7003 – Current sensing

Q4022 - PWM

T7002 - FBT

Q4018 – H Output

Leakage or shorts in any component in the above path will permit voltage
to pass through D7102 into the G board’s protection latch.

FBT Output OVP

If a resonate capacitor in the H. output stage opened, or if Q4022 shorted,
the high voltage from the T7002 FBT could go dangerously high. To
prevent this danger, a flyback winding is monitored for excessive voltage.
Reference Module PM26 detects this danger and applies voltage through
D4060 into the protection latch on the G board. This will shut down the
TV set.

H Centering IC4003 OCP

A shorted horizontal centering driver IC4003 could damage the FBT and
the horizontal output transistor. To detect this failure, Q4013 monitors
the current consumed by the centering IC4003. After the failure, Q4013
applies voltage through D4011 into the protection latch on the G board.
This will shut down the TV set, preventing further damage.

Troubleshooting Concept

A failure in any one of the stages being monitored will apply a voltage
through a blocking diode across the CN5002/CN4001/pin 9 board junc-
tion and trip the protection latch on the G board. You can determine
which section has failed by measuring the anode of each blocking diode
as the set shuts down. Normally there is no voltage. A voltage indication
identifies the problem block connected to that diode.