So what will be my next steps in the diagnosis process ?
With the major IC's anonymised life becomes challenging. They will be placed under a microscope in an effort to find any remaining identifying marks but that may well be fruitless.
I have decided upon a two pronged attack. I will try to gather IC datasheets for the chipset but I will also jump to the probing stage of the investigation.
Those trained in fault tracing will be familiar with the 'half split method'. I use this to reduce the potential fault landscape and it often enables me to focus on a specific PCB, or part thereof. Other approaches include the standard data path testing front to back, or back to front. That is to say, you follow the Data from its origin, through any processing stages and to its eventual destination. The reverse is also possible where a lost data input along the chain is suspected. This is more suited to analogue circuits really as data is not always simple to trace through VLSI systems.
I know that the UL 03 16 2 microbolometer is the origin of the systems scene data. I also know that it requires certain specific inputs in order to operate and that it produces an analogue 'Video' signal output on one pin. The 'video' signal is RAW, it is not composite video, it has no sync information within it. It is the RAW output from the ROIC pixel readout. That video signal will only be present and correct if the microbolometer ROIC is 'happy'. To be 'happy' all inputs to the ROIC and configuration commands must be correct. The microbolometer video output is therefore a logical place to start the probing investigation. If there is an incorrect signal at that point, nothing else downstream will be correct and the investigation will move to the microbolometer inputs and configuration.
If all is well with the microbolometer video output the investigation moves to the various video signal processing stages in the system. The video signal is first converted from the analogue domain into the digital domain using a fast ADC. From there it enters the video processing stages and that is where things become complicated when it comes to probing and diagnostics. The identity and pinout of the VLSI IC's is very helpful here.
My current assessment of the situation is that the microbolometer MAY be functioning as the FFC events are present. It also could be that the Microbolometer is NOT functioning but video processing stages are carrying out their usual FFC routine and just 'seeing' a null input. The good news is that the core appears to have a functioning operating system so hopefully we are not looking at an OS fault or corruption.
There will be a video processor IC in the core that is responsible for the DSP on the video coming from the microbolometer video output. The video will be processed and then combined with the Overlay graphics for the display. The Overlay graphics and menu system all function correctly so it would appear that either the video processor has lost its input from the microbolometer signal path, or it is suffering a fault in its own realm. It would be great to identify the video processor so that signal probing can be carried out on its pins. In the half split method the input and output of that IC would be key check points.
Well this will have to wait as I am off to a Wedding. I shall start the microbolometer checks tomorrow.
Oh...... is anyone wondering how I will identify the various pins on the microbolometer ? An important question
I already have the 03 16 2 pin out and datasheet. Guide have also helpfully labelled the pins use on their microbolometer PCB
A quick Google search finds a datasheet for the UL 03 16 2 as well.
http://www.chronix.co.jp/chronixjp/products/picture/ulis/pdf/UL03162JP.pdfHow will I probe the core when it is a 'stack' design ? It is an arduous task involving destacking, soldering of fine wire taps to points of interest, restacking and testing. The core stack sits in the middle of a 'pin board' and the test point fine wires extend out from it to test points surrounding the core. The unit can end up looking like a flipping May Pole on the test bench
It is an arduous and time consuming process that I do not enjoy, but there is little choice as the stack must be complete to operate. The OEM has the benefit of either individual PCB test jigs or connector extender ribbons to 'explode' the core. Such is justifiable if dealing with a lot of one model of core. I did such when diagnosing and repairing the 21 ARGUS 2 thermal cameras and it saved a lot of time and effort.
What is a May Pole ? .... look here.....
http://projectbritain.com/mayday/index.htmlFraser