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Theory of Operation
3–6
SPG 422 Service Manual (B034000 and above)
Power Supply
The switching power supply generates 5 V for TTL and ECL devices. A stable
linear supply of 12 V is provided for powering the analog circuitry.
This type of power supply is called a current-mode-controlled, discontinuous,
flyback, switching power supply. The current output is distributed between the
four supplies as follows:
+ 12 V
0.8 Amps max
+5 V
7 Amps max
–5 V
6 Amps max
–12 V
0.8 Amps max
The maximum power is limited by the maximum current in the primary of the
power inductor. This is also the only current limit for the
±
5 V supplies, as they
have no secondary current limit. The
±
12 V supplies are current limited on the
secondaries by the
±
12 V linear regulators and the secondary
±
14.5 pulse width
modulator.
There is also circuitry to provide for operation from both 110 and 220 VAC
supplies, over-voltage protection (crowbar) on the +5 V supply, and shutdown
circuitry that forces a restart of the supply if it remains in current limit for more
than a short period of time (
≤
200 ms).
WARNING.
All primary voltages are referenced to a floating ground, not chassis
ground. Potentials to chassis ground can be much higher and the possibility
exists that you could electrocute yourself.
Option 1 Board
The SPG 422 Option 1 board contains four identical, separate dual-standard
black generators. Each generator runs on a 27 MHz master clock, with PAL and
NTSC frame resets to synchronize them and some microprocessor setup
information to program them.
The four black generators are controlled by the microprocessor and the Control-
ler PLD, which takes the video standard selection for each channel and selects
and processes the appropriate frame reset pulse for each generator. The Control-
ler PLD also generates the necessary microprocessor interface signals for each
Encoder.
Summary of Contents for SPG 422
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Page 14: ...Service Safety Summary x SPG 422 Service Manual B034000 and above ...
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Page 96: ...Performance Verification 4 4 SPG 422 Service Manual B034000 and above ...
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Page 158: ...Maintenance 6 14 SPG 422 Service Manual B034000 and above ...
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Page 223: ...9 3 SPG 422 Service Manual SPG 422 Component Digital Sync Generator FRONT PANEL 1 ...
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Page 226: ...SPG 422 Service Manual 9 6 A2 Digital Board Static Sensitive Devices See Maintenance Section ...
Page 227: ...9 7 SPG 422 Service Manual SPG 422 Component Digital Sync Generator CPU 1 ...
Page 228: ...SPG 422 Service Manual 9 8 A7 Serial Filter ...
Page 229: ...9 9 SPG 422 Service Manual SPG 422 Component Digital Sync Generator CPU I O 2 ...
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