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DP-4X LED (Visual Trouble Detection) CIRCUIT EXPLANATION
This explains the LEDs used in the Deflection Power Supply used for Visual Trouble Shooting Circuit Dia-
gram explanation:
(See the LED (Visual Troubleshooting) for the Deflection Power Supply Diagram on the next page for details)
2 GREEN LEDS
In the DP-4X chassis, there are 2 Green LEDs that can be used for Visual Trouble shooting. The Service Techni-
cian can use these LEDs to determine if the set is experiencing a problem within these two Power Supplies..
The LEDs can be used in the following ways.
OFF:
If the LED is off, then the power supply that is being monitored is unavailable. (Excluding the possibil-
ity that the LED itself is malfunctioning). NOTE: If DP40 LED opens, then the set will be in shut down
condition because of its current flow explained below.
If the LED turns on but then quickly goes off before the others, then the power supply that is being
monitored can be suspected.
ON:
If the LED is on, then the power supply that is being monitored is working normal. (There is the possi-
bility that the power supply being monitored may in fact be present but low. If after making visual in-
spection and all seems OK, but there's still a problem, be sure to check the accuracy of the power supply
in question.
GREEN LEDs DP50 and DP40.
DP50 (SW + & - 28V)
•
Monitors the SW +28V output from TP01 pin 16 and rectifier DP30. Filtered by CP32 and CP34.
•
Note: This LED requires the SW –28V power supply to be functioning to operate. Current flow for light-
ing DP50 is from the SW+28V through RP46, DP50, RP47 to the SW-28V. If the LED opens, or the
negative SW –28V is missing, this LED will not illuminate. If the SW –28V is missing, the set will shut
down.
DP40 (SW +115V)
•
Monitors the SW +115V output from TP01 pins 10 and 11. Rectified by DP34, filtered by CP45.
•
This power supply is used for Deflection and High Voltage generation.
NOTE: Both of the Green LEDs are also involved in the Shut Down Circuit.
•
DP50 supplies SW+28V to the Cathode of DP46 if the negative SW-28V is missing. This action will
cause the zener to fire and supply a high through DP47 to the PROT_OVP shut down Circuit.
(See the Deflection Power Supply Shutdown Output Diagram Explanation Page 01-08 for details).
•
DP40 supplies the Ground return path for the Voltage divider comprised of RP38 and RP39. These in
turn are connected to the SW +115V deflection B+. If the voltage on the cathode of DP39 goes too high,
the zener will fire and supply a high to the PROT_OVP shut down Circuit.
(See the Deflection Power Supply Shutdown Output Diagram Explanation Page 01-08 for details).
There are additional components in the Shut Down circuit that are not shown in this diagram. Please see the De-
flection Power Supply Shutdown Output Diagram Explanation Page 01-08 for details.
PAGE 01-21
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