Q
The Remote Control PCB houses the:
| CONTROL | DESCRIPTION | CIRCUIT |
1. | H SIZE | Horizontal raster size | Diode modulator |
2. | V SIZE | Vertical raster size | Vertical control |
3. | V RAS. POS. | Vertical raster position | DC current to V. yoke |
4. | H POS | Horizontal picture position | H. sync delay |
5. | M GAIN | Master gain | Video interface |
R
The Horizontal Size Control circuit has four inputs:
# | SIGNAL | FUNCTION |
1. | Horizontal size | Horizontal size control |
2. | Beam current | Blooming control |
3. | Vertical linear ramp | |
4. | Vertical parabolic + V. linear ramp | |
|
| (Pincushion) |
The horizontal size control circuit sums the four signals at one node plus the feedback from the diode modulator to drive a switching mode power driver. The output of the power driver is then connected to the diode modulator through an inductor to complete the control loop.
S
The Diode Modulator is a series element of the horizontal tuned circuit. It forms a node between GND and the normal yoke return circuit. If this node is shorted to GND, the result is maximum horizontal size. Forward current in the diode modulator, at the start of retrace, keeps the node voltage clamped to ground until enough current flows from the horizontal tuned circuit to exceed this forward current. The horizontal size, therefore, is controlled by controlling the current to this diode via the horizontal size control circuit.
T
A Voltage Doubler is used in the power supply for two reasons:
1.To improve the efficiency of the power supply.
2.To permit 120 volt and 230 volt operation. For the 230 volt operation the voltage doubler is replaced with a bridge rectifier.
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