MadeforThat,
I have just had to call time on repairing a modern UNII-T UTi690B camera and I feel your pain. I hate giving up on a thermal camera and often spend way too much time on a 'patient' trying to revive it. I have had to learn to 'let it go' when it becomes a "time gobbler"
With regard to your BST camera.... it is a very interesting design that I have not seen before. A very boxy format that is clearly designed for utility rather than good looks ! I have several BST technology fire fighting cameras in my collection and E2V/MARCONI ARGUS remain my favourites. The Argus 2 is a bit of a 'Beast' in terms of size but it is well suited to the intended gloved use and very robust. You will not be surprised to hear that some have been sold to film prop companies for use as 'firefighting' cameras or Sci-Fi 'Ray' runs in films ! The Argus 3 was a change of format that you either love or hate. I find myself torn as I like the format, but did not like the large side handles. Well suited to the intended use by fire-fighters, but bulky as heck. I fitted the optional 'slimline' side panels in place or the handles and prefer that configuration. It remains quite large compared to more recent fire fighting cameras, but it can produce nice imagery.
We cannot avoid the elephant in the room though..... BST is an obsolete thermal sensor array technology so is it really worth repairing BST based cameras when modern microbolometer based cameras have become more affordable ? That is a difficult question for me as I respect both technologies. BST does not normally provide a temperature measurement due to the physics of the FPA's operation. The dynamic range of BST is limited so a mechanical IRIS is often employed and the chopper wheel uses a clever membrane to improve performance. The technology was clever and deserved further development. BST offers continuous imaging without the need for FFC flag calibration freeze frames. Those interested in video recording in the thermal domain prefer not to have these freeze frame events present in their recordings. The down side is the mechanical nature of the BST FPA pixel reset using a spinning chopper wheel. With some thought, the chopper wheel could be made quite sophisticated and compact as E2V demonstrated in their military designs. But is the image produced by a BST technology camera any good ? In my experience, the BST based cameras required less clever noise reduction and image processing than early microbolometer cameras. The image in a healthy BST camera system can be very nice indeed. Systems that are showing their age and need some TLC start to show increased noise in the image and the display systems can start to show their age. It needs to be remembered that most BST Fire Fighting cameras provide a 320 x 240 pixel image with a high image refresh rate of anything from 25fps to 60fps.
Once BST development ceased and the focus was moved to Microbolometer development and noise reduction, the World began to forget BST technology. The Microbolometer has come a long way since I first tested it in 1997 in the ground-breaking FLIR PM570 camera. Modern microbolometer thermal cameras come in many formats and quality levels. It is possible to buy a 256 x 192 pixel 25fps microbolometer camera for less than $300 and even less if you can live with a mobile phone dongle format solution. The size and performance of these modern cameras is impressive, given the relatively low cost. It is enough to make people think carefully about whether they but an older BST technology camera or a new microbolometer technology camera from ASIA. The older fire fighting cameras are often beautifully built and very rugged, modern budget microbolometer cameras, less so ! I love the ARGUS 4 and ARGUS MiTic modern Firefighting cameras but you need deep pockets to afford them, even if bought used.
Your thread title reads "Repair or let die". I always try to revive a thermal camera but there is a need to be sensible when dealing with technology that has limited intrinsic value. If I have a very unusual thermal camera in my collection, I will go above and beyond all sensible effort and expenditure to get that camera running again and in nice condition. I am a collector though so can be illogical in my efforts to repair a camera. A general user of thermal cameras needs to decide what a poorly camera is actually worth and ensure that they do not spend more than around 60% of its value and there will be the investment of time to be considered as well. The good news is that there are reasonably priced BST technology cameras on the used market as the cameras are often overlooked by those wanting more modern looking technology.
With this in mind, I would look to repair your camera using a parts donor bought via eBay but I would limit the amount I would spend on the donor unit. A very battered Argus 2 often has a pristine condition electronics package safely protected within the well designed inner waterproof and dustproof casing. If you decide to sell your camera as a project for someone else to repair, I feel sure you could get a reasonable sum for it as it is an unusual model. If you want BST technology thermal imaging then look for a nice condition Argus 2 or Argus 3 but be sensible about the price you pay. The Argus 3 gives you a colour LCD display over the monochrome CRT used in the Argus 2.
Fraser