MG5.1E
5. SCAN CIRCUITS
25
5.1 Line Drive
Personal notes
Line Drive from the Small Signal panel is fed to connector 1509
Pin 1 and then to buffer transistor 7803. (Figure 5-1) Transistor
7803 then drives the Line driver transistor 7801. Line drive is
then fed to the Line output transistor 7802. Transistor 7802
drives the three Line Yokes and the Scan transformer 5801.
The Scan transformer produces a 240 volt supply for the CRT
drive circuits, a Filament drive for the CRT'S, a plus and minus
13 volt supply for the Frame drive circuit. It also produces a 28
volt supply for the beam limiter circuit in the High Voltage circuit.
The output of the Line Output transistor 7802 is also fed to
buffer transistors 7800 and 7804 to produce a Line Sync pulse
(HPUL) and Line feedback pulses to the Small Signal panel (H-
PUL and HFB). The output of transistor 7804 also produces a
Line Blanking pulse (HPUL-BLNK).
Drive for geometry correction from the Small Signal panel on
the E-W line drives transistors 7553, 7551, and 7552. This
circuit drives the return side of the Line Yokes to provide
Horizontal corrections to the geometry. Geometry correction
drive, E-W, is also fed to transistor 7830 which produces drive
for the Dynamic Focus, LV. The Line component to the
Dynamic Focus is added in transformer 5802.
The Line Sync (HPUL) is used to synchronize the High Voltage
drive. If this pulse is missing, the High Voltage circuit will shut
down. A loss of drive to the Line Yokes will cause the High
Voltage to shut down.
