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DP-4X SIGNAL POWER SUPPLY SHUTDOWN CIRCUIT EXPLANATION
See the DP-4X Signal Power Supply Shutdown Circuit for details. This includes inputs (E) and (F).
There are a total of 20 individual Shutdown inputs to the Relay Inhibit transistor Q203 shown on the Signal
Power Supply Shutdown Circuit.
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There are 8 individual Shutdown detection circuits on the Signal Power Supply Circuit Diagram.
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There are a total of 5 individual Shutdown inputs from the Deflection PWB via PROT_OCP (active
Low). Input from the PPS1 connector pin 45
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There are a total of 7 shutdown inputs from PROT_OVP (active High) input from the PPS1 connector
pin 47.
SHUTDOWN INPUTS EXPLAINED:
Q204 and Q203 Relay Inhibit Activation. (SHUTDOWN) called COMMON ACTION CIRCUIT.
All Shutdown events will cause the main power relays to turn off. This action will stop all secondary power
supplies. The Low Voltage Signal Power Supply will Shutdown along with the Deflection Power Supply.
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Q203 CIRCUIT EXPLAINED:
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If any of the shutdown circuits activate, the base of Q203 will go High. This turns on Q203 and removes
the Power On Highs from PPS1 connector pins 9 (Power_Sig) and 11 (Power_Def) called Power_1 and
Power_3. With this, the main power supplies will STOP. Q204 operates as a "latch". This prevents
Q203 from turning off if the shutdown signal disappears after shutdown.
POWER ON/OFF RELAYS RY101 and RY102:
RY101 Explained:
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The Relay RY101 supplies AC to the Signal Power Supply bridge rectifier DS201. When this relay en-
gages, the Signal Power Supply starts up and supplies the voltages mentioned below.
SIGNAL (Low Voltage) POWER SUPPLY:
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The Signal Power supply is centered around the Switching Transformer T201 and the driver IC, IP01.
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This power supply creates voltages that are Switched on when the Set is turned on.
1. 38.5V or 29V
4. SW-5.6V
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Other supplies are generated from these 6 main voltages.
RY102 Explained:
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The Relay RY102 supplies AC to the Deflection Power Supply bridge rectifier DP01. When this relay
engages, the Deflection Power Supply starts up and supplies the voltages mentioned below.
DEFLECTION (High Voltage) POWER SUPPLY:
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The Deflection Power supply is centered around the Switching Transformer TP01 and the driver IC, IC201.
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This power supply creates voltages that are Switched on when the Set is turned on.
1. SW +115V
4. SW-28V
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Other supplies are generated from these 6 main voltages.
CIRCUITS ATTACHED TO THE BASE OF Q203:
This year, Hitachi is utilizing a three legged diode OR gate style of input device for feeding shutdown inputs
to the base of Q203. These diode OR gates and circuits attached are explained next.
2. +10.5V
5. +16V
2. +220V
5. +7V
3. +21V
6. SW +5.7V
3. +28V
6. SW +6.3V
(Continued on page 11)
PAGE 01-10
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