Author Topic: Repair or let die  (Read 3019 times)

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Offline Fraser

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Re: Repair or let die
« Reply #25 on: July 19, 2023, 05:46:24 pm »
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"  ;D

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

« Last Edit: July 19, 2023, 07:24:05 pm by Fraser »
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Offline Fraser

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Re: Repair or let die
« Reply #26 on: July 19, 2023, 05:57:43 pm »
And just as a foot note.... if I had your camera, I would repair it !  :-+

Sady even if I were given the opportunity to buy your camera, the shipping and taxes would likely make it just too expensive for me  :(

Fraser
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Offline Fraser

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Re: Repair or let die
« Reply #27 on: July 19, 2023, 07:00:27 pm »
Another comment on BST cameras. If they offer a video output to connect an external monitor…. Try connecting a decent monitor to it. You may be surprised at the improvement in image quality. Some early generation Colour LCD displays can be quite poor performers with a grainy appearance. Upgrading a camera to a more modern LCD panel is sometimes possible but much depends upon the signal produced by the video output stage.

Fraser
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Offline Bill W

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Re: Repair or let die
« Reply #28 on: July 20, 2023, 09:45:34 am »
I guess the question I would pose, if this was your camera, would you bother finding replacement components, or just buy a similar vintage argus/Scott for 200$? I think it's a cool form factor in the box, but not sure it was ever better than the competition in terms of durability. Wondering if there any parts off of this unit that I could sell to you good folks to recoup a few of my bucks haha. You mentioned the detector is the only export controlled item?

A replacement SECCA is easy !  PM me
Seems likely to restore decent, if not perfect, image as noted above.
Might even be the best way to recoup costs and buy a good condition Argus.

Yes you can get a BST core camera for around that, but if hoping for a spares donor would need to know it is an 'analogue' 200A type.  Argus2 used both so you would need to check serial numbers to be sure - and hope it did not have a replacement core at some time in its' life.
ISG Talisman would be another possibility for salvage.

Bill

Offline Bill W

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Re: Repair or let die
« Reply #29 on: July 20, 2023, 09:49:15 am »
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.


They are almost all 60Hz 'NTSC'.
There was an option on the later digital BST to switch to 50Hz 'PAL' which windowed the 320x240 thermal image into a 384x288 picture.

( I say NTSC / PAL, the cores were of course monochrome)

Bill

Offline MadeForThatTopic starter

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Re: Repair or let die
« Reply #30 on: July 21, 2023, 03:46:54 am »
Thanks for the replies guys! I guess I will keep my eye out for a core in case I can luck out on another "deal" like this one lol. My other alternative idea for this case would be a pretty sick machined birdhouse, with the old lens hole being the new entrance haha, but restoring the camera to decent glory would be ideal haha! From what I can tell, this core has both power and vid out pins, I am not sure if any of the other boards are needed? See the pins I bent on the image. I have no real need for the spot temp reading, or the automatic iris, or any of the other features. I just want to see hot and cold in B/W contrast lol. Anyone have an idea what the operating voltage of the core would be? I assume 5v, but have no real support for that. My running theory is that the bodgery on the ratheon board is for the spot temp display, but I have no idea haha. I am all for testing with the least number of variables, especially when I don't understand how something functions  haha
« Last Edit: July 21, 2023, 03:51:01 am by MadeForThat »
 

Offline Bill W

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Re: Repair or let die
« Reply #31 on: July 21, 2023, 12:24:09 pm »
From what I can tell, this core has both power and vid out pins, I am not sure if any of the other boards are needed? See the pins I bent on the image. I have no real need for the spot temp reading, or the automatic iris, or any of the other features. I just want to see hot and cold in B/W contrast lol. Anyone have an idea what the operating voltage of the core would be? I assume 5v, but have no real support for that.

Not 5V, await detailed reply.
Yes you should be able to run as 'volts in - video out' with just the PCB with the detector on it, the 'SECCA' and the chopper motor / sensor etc.

As earlier, I have no idea how they made a BST do on-sensor spot temperature readings.  Is it the 'standard' chopper wheel ?
See teardowns here or on my site:
http://www.fire-tics.co.uk/project3/index.htm
and
http://www.fire-tics.co.uk/spares.htm

Everyone else using BST had to fit a separate spot temperature sensor unit - usually a Raytek.

Offline MadeForThatTopic starter

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Re: Repair or let die
« Reply #32 on: July 21, 2023, 02:18:59 pm »
Yeah it didn't look much different from the chopper spare you have available, not sure what I would be looking for on it. Seems the measurement was pretty sensitive, but I didn't check accuracy.
 

Offline Bill W

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Re: Repair or let die
« Reply #33 on: July 21, 2023, 08:43:33 pm »
Ok, that shows the classic dark halo - it is a standard Raytheon BST with some unknown magic to read spot temperatures when running the standard chopper wheel - 'clear' and 'dispersive' segments.

You can check the volts on the PWR connection to see what is being fed into the Raytheon side.  I have not got the full data to hand, but ran these from 8 x NiMH, 8 x AA LR6 and 5 x NiMH.
Keep below 12V especially on an early core as the tantalum caps can be fragile.  We had a lot of dead cores from folks wiring them to vehicle supplies.
10V is happiest, as it keeps the current demands down, but it will run down to 4.5V.

One possible dependence on the rest of the camera is if it is running with fixed / calibrated gain / offset ( ? maybe to aid the spot temperature function ? ). 
That would mean sensor gain/offest set from one of the other PCB.  We did the same in Argus2 & Argus3 and hence the 'set to manual' instructions I give in the tearup pages.  An analogue core only has those DC controls which you might need to bypass to go stand-alone.
https://www.eevblog.com/forum/thermal-imaging/argus-3-(bst)-teardown-and-repairs/44/
Down from post 44

Offline Bill W

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Re: Repair or let die
« Reply #34 on: July 21, 2023, 08:58:04 pm »
Some thoughts on the 'on screen' temperature measurement.  How might you do it with a BST - and why such a problem.

The chopper is the first issue, BST only senses temperature changes hence the chopper.
Second is the need for an iris to stop the lens down when viewing hot objects.

So you need to know where the iris is (looks like this camera might have a stepper motor drive), what the temperature of the iris is, and then what video signal represents a given temperature difference - and finally what that is a temperature difference FROM !
The Argus2 & 3 were set up for a given gain (video height of a 5°C differential)

As above, everyone else (EEV/Marconi, ISG,  ISI, Bullard ) simply fitted a separate sensing head from Raytek


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