Service manual

There are several types of protections:
• I
2
C related protections (e.g., +5V supply check).
• HOP related protections (mainly for deflection items).
• Hardware errors which are not sensed by the Painter (e.g., BRIDGE_PROT)
I 2 C Related Protections
In normal operation some registers of the I
2
C controlled ICs will be refreshed every
200ms. During this sequence, the I
2
C busses and the I
2
C ICs as well will be checked.
The I
2
C protection will take place if the SDA and SCL are short-circuited to ground or
to each other. An I
2
C error can also occur if the power supply of the IC is missing (e.g.,
FBX_PROT: error 1).
HOP Related Protections
Every 200ms, the status register of the HOP is read by the Painter via I
2
C. If a
protection signal is detected on one of the inputs of the HOP, the relevant error bit in the
HOP register is set to 'high.' If the error bit is still 'high' after 1s, the Painter will store the
error code in the error buffer (NVM) and, depending on the relevance of the error bit, the
set will either go into the protection mode or not.
• HFB: Horizontal Flyback.
If the horizontal flyback is not present, then this is detected via the HOP (HFB_X-
RAY_PROT). One status bit is set to 'high.' The error code is stored in the error buffer
and the set will go into the protection mode.