G2 CONNECTOR
P1205
FOCUS
CONNECTOR
CRT DRIVE ADJUST
RP1
Figure 3 6 - CRT Drive Panel
CRT Drive Panel
There are three Drive Panels, all of which are
identical in circuitry and component layout,
Figure
36. The major components are: G2 and
Focus leads, Push Pull CRT Driver Q1/Q4, Video
Amplifiers Q2/Q3, and CRT Drive Adjust RP1.
After color signal decoding, the Sync and 2Vpp
R,
G, and B Video signals are fed to their respective
CRT PAnels. In
Figure
37, the Blue Video sig-
nal is shown coupled to J803 and amplified by
Q3/Q2 (Q2 serves as part of the Q3 collector
load). Q3/Q2 outputs 100Vpp inverted Video to
the Q1/Q4 push pull amplifiers, which drive the
cathode of the Blue CRT with 10OVpp
Sync-positive Video.
When the set is turned Off, or when ac power is
interrupted, or when Horizontal and Vertical
sweep voltages are removed because of a shut-
down condition, the CRT beam currents could
produce a high-intensity spot on the faceplate
and permanently damage the phosphor coating.
This possibility exists because 30KV anode
voltage is still present for a short period after
the power supplies have been turned Off. The
Spot Killer circuit protects the CRTs by cutting
Off beam current whenever one of these inter-
ruptions occurs.
When the set is turned On, 200Vdc is developed
by the power supply and fed to the CRT Panel
circuits through J801-1. In the Spot Killer
circuit, the negative end of the capacitor C4 is
grounded through conducting diode D2. C4
charges to the full 200Vdc supply. D2 remains
forward biased as long as the supply voltage is
Summary of Contents for 6810
Page 3: ...Figure 1 Signal Flow Block Diagram...
Page 15: ...Figure 14 TS10 Tuning System Block Diagram...
Page 20: ...Figure 20 Decoder Module Signal Flow Diagram...
Page 30: ...Figure 31 Comb Filter Module Figure 32 Comb Filter Circuit...
Page 35: ...Figure 37 CRT Drive Circuit 4...
Page 41: ...Figure 47 Keystone Trapezoid Generator o Figure 48 Side Pincushion Generator...