System Safety Loop - Barco F70 Service Manual

GP7 system functional description
firmware on a USB memory stick and inserting it in the system's USB port. When system powers up, it will
automatically detect and load the upgrade without more intervention by the user.
System firmware consists of the following parameters, and will load a combination of pre-sets, based on the
part number it is named with, as well as the color wheel cassette ID it is currently equipped with.
New features and updated functionality will be released and posted on the web. It is recommended that the
system is kept updated with the latest firmware release.
INPUTS FPGA DLP TI LOOP
SW
Image 5-5
CW Algorithms
Different color wheels require different timing algorithms to synchronize the DMD against the color wheel.
These algorithms are stored in the system. The correct algorithm is automatically selected by the system
based on the ID of the colorwheel cassette in use. Please observe that the system has no automatic facilities
to detect the index timing as this is individual for each and every colorwheel. Consequently, after replacing the
colorwheel, index adjustment must be performed in the service menu.

5.6 System Safety Loop

About
The projector is equipped with an internal safety loop ensuring that the system is not damaged if the internal
temperature exceeds normal temperature range. The safety loop was introduced as an additional Hardware
safety requirement in new projectors around 2010.
The safety loop in GP7 is primarily build up by a combination of bimetallic switches, mechanical switches and
NTC thermistors.
This system is also known as thermal loop, designated to monitor each corresponding light path. A total of 3
bimetallic switches are connected in serial within the system. There are two bimetallic switches for each light
path and one on the DMD Heatsink (cold plate).
Bimetal switches are normally closed while in operation, but will open when temperature exceeds threshold
temperature (90°C). This loop of bimetallic switches is controlled from the DC Power supply, and if one switch
releases the system will power down.
There are also four mechanical switches included in this loop, two at the bottom cover and two by each Laser
cluster detecting they are in correct position.
Finally there are 12 NTCs, one at each laser bank adjusting the input effect to the lasers, dependent of
temperature. If the measured temperature exceeds 84°C lasers will be shut down by the laser drivers.
Each loop can be measured with a multimeter in order to detect an open circuit in the loop. This must be
performed with the projector switched off / disconnected from the power source.
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