Service manual

In this chassis, a 'one-point' cut-off control is used:
A current of 8A (for cut-off) is fed to pin 44 of the HOP. This is done with a
measurement pulse during the frame flyback. During the first frame, three pulses are
generated to adjust the cut-off voltage at a current of 8A. With this measurement the
black level at the RGB-outputs is adjusted. So at start-up there is no monitor pulse
anymore.
At start-up, the HOP measures the pulses, which come back via pin 44. The RGB-
outputs have to be between 1.5V and 3.5V. If one of the outputs is higher than 3.5V or
one of them lower than 1.5V, the RGB-outputs will be blanked.
Geometry Control
All geometry control is done via I2C and the data is stored in the NVM (IC7012) of the
SSB.
Line Drive (LINEDRIVE1).
Line drive is derived from an internal VCO. As a reference an external resonator is used
(1301). The internal VCO is locked with the HD100-pulse, which comes from the
PICNIC. The 'PHI-2' part in the HOP receives the HFB_X-RAY_PROT (pin 13) to correct
the phase of the line drive. The EHT-info is supplied to pin 14 (DYN-PHASE-CORR) to
compensate picture breathing depending on the beam current.
Frame Drive (FRAMEDRIVE+).
Triggered by Frame+ output of HOP-IC (pin 1), the FRAMEDRIVE+ signal is extended
to 530uSec (flyback time) by the circuit around TS7309 and 7311. (Vsync signal is used
to vertically sync the painter)
Note: The Frame outputs (pins 1/2) of the HOP are not used!