Mitsubishi C-6919 Service Manual page 39

3.6.3 +6.3 Vdc Regulator
The +6.3 Vdc is used by the CRT heater.
The +6.3 Vdc regulator is supplied with ac power from
secondary of T991, is rectified by 0903, filtered by
C910 and applied to the collector of Q904.
Q904 serves as a series voltage regulator.
The base of Q904 is clamped at approximately 7 Vdc
by 0906 and R914.
Assume that the +6.3 Vdc; emitter of Q904 tries to
go
in the positive direction, decreases the conduction
of Q904.
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