Philips GM 5605 Manual page 30

Circuit description 31
voltage. This voltage variation is passed to the control grid of valve
B1001 via the voltage divider RI009//R1012-R10! 1. The voltage applied
to the control grid is considerably amplified owing to the large anode
resistor (R1005).
From the anode of valve BI001' the amplified signal, which is opposed in
phase to the original voltage variation, is applied to the control grid of
series regulator B100I. As a result this valve, dependent upon a positive or
negative voltage variation of the +280-V voltage, will carry less or more
current, so that the original voltage variation is compensated for. The
ripple voltage on the +280-V voltage is also fed back. The feedback
factor for the ripple voltage is, however, much greater than that for the
d.c. voltage, due to the use of capacitor CI003 in parallel with R1009.
The current which must be supplied by the -f 280-V supply part is larger
than that supplied by the series regulator. Resistor R1003 is, therefore,
connected in parallel with B1001.
Voltage divider R1003-R1004 is provided for hum compensation.
2. +160 V
This voltage is derived from the -f 280-V supply voltage by means of
voltage divider R1019-R1020.
3. -150V
This is the full-wave rectified and smoothed a.c. voltage supplied by
winding S3 of the supply transformer.
The voltage of —150 V is among others applied to the Wehnelt cylinder
of the cathode ray tube via R1.
The brightness of the picture can thus be adjusted by means of potentio-
meter RI.
4. +1610 V
The a.c. voltage taken from winding S7 of the supply transformer is
halfwave rectified by means of valve B1003. The rectified voltage is
applied to the post-acceleration anode of the cathode ray tube.
5. Heater voltage
The heater voltages for the various valves are derived from windings S4,
S5, S6 and S8.
The windings S5 and S6 are brought at a d.c. voltage potential.
This prevents breakdown in case the maximum permissible voltage
difference between heater and cathode is exceeded.