9600 Service Manual - gmecorp-usa.com

Image System 31
CCD Thermo-Electric Cooling Circuit (TEC)
The CCD sensor is cooled by a thermo-electric cooling (TEC) and heat sinking
apparatus. The cooling module attempts to maintain the CCD temperature at the same
temperature as the image intensifier housing. Poor image quality may indicate that the
TEC circuit is not working properly.
The heat sinking apparatus is turned off and on periodically by firmware located on the
Image Function PCB. The ON and OFF cycle times depend on how long the processor
has been running.
A +5 VDC is applied to R4 on the Image Function PCB. Current flows through R4 to the
thermo-electric cooler, back into the Image Function PCB and through transistor Q3 to
DC common ground. Micro-controller U16 pin 19 controls the base of transistor Q3. A
high on pin 19 turns the cooler ON and a low turns the cooler OFF. These times have
been determined experimentally and are stored in a look-up table (LUT) on the Image
Function PCB. To determine proper operation of the TEC circuit, measure TP3 on the
Image Function PCB for a drop to +2.4 VDC ± 0.75 V. The E9 jumpers are not used at
this time.
SYNCHRONIZATION STANDARDS
A 60 Hz and 50 Hz model CCD Camera is available.
Domestic Models - RS-170A Video Waveform Standard, 60 Hz.
International Models - CCIR or PAL compatible with 576 lines centered in the
unblanked area of the CCIR standard, 50 Hz.