Teardown of an ISG Talisman Thermal Camera by Mike

[Fraser]

I have just seen that Mike did a teardown of an ISG Talisman thermal imaging camera.



The camera is a Pyro-electric Vidicon based unit that predates the later BST and Microbolometer technologies.

It is still a useful camera and, when set up correctly, produces a decent image.

Mikes camera needs the voltages on the tube setting along with the electronic focus, so it is blurry on his video. Pyro Vidicon's are capable of  better images than shown here.

I own some ISG Talisman Pyro vidicon based units and later ISG Talisman Wasp's that use a BST detector. The Wasp produces a superior image, has a X2 image magnification mode and temperature measurement. My Talisman cameras are in need of some repair or 'calibration' so I will upload pictures of their internals here, as and when I get to them on my to-do list.   

[mikeselectricstuff]

Tesla500 also looked at a similar unit a while ago

[TopLoser]

I bought a couple of those Talisman cameras a few weeks ago, £50 each in non-working condition. They looked exactly like the ones in the video but had a solid state sensor instead of the videcon - looking at the video output from the camera it looks like the sensor resolution is 320x240.

The faults were easy enough to fix, the spinning shutter wasn't working on either of them. Bought new motors and they both came back to life.

[Fraser]

Hi Toploser,

The Original Talisman was a Pyro-Vidicon unit but the model progressed to 320x240 BST detector and used the same case. Obvious differences are that the BST units have a sharper edged PTFE lens shroud and a multi pin configuration socket adjacent to the handle. The next generation of Talisman was the 'WASP'. It is a 320x240 BST detector unit and is basically a slightly different case with RF transmitter and 2X Electronic Zoom function. BST based TICs are very good quality so you should be getting a decent image from them.

I am interested to hear that yours had failed rotary shutter motors. I understand the shutter was the weak point in most systems that needed them. Are you able to share identity and your source for the new motors ? I currently own one Pyro-Vidicon Talisman and three BST WASP's.

Regards

Fraser

[TopLoser]

One of mine had the configuration connector, the other didn't. One had a black lens shroud, the other was white. I guess they just used whatever bits they had lying around during the transition from one model to the next!

The image quality is excellent. I wish the focus wasn't fixed, but £50 for a 320x240 resolution TIC I can't complain too much can I?

I got the motors from FAULHABER, DC-Micromotor 1516T012S

http://www.faulhaber.com/servlet/com.itmr.waw.servlet.Anzeige?fremdaufruf=ja&kdid=40929&sprachid=1&htdigurl=/n167866/i86089.html

Hope that helps,
Ian

[Fraser]

Thank you for the info. Much appreciated.

For close up electronics work just place a ZnSe lens in front of the fixed lens. (no mods needed) I acts like a jewellers Loupe for the TIC !

A 20mm diameter ZnSe lens with 100mm focus distance is approx. $30 delivered via e*ay

[TopLoser]

100mm focal length lens on its way to me 

Next mod is to junk the smelly yellow case and internal CRT, replace with nice new housing and LCD 

I've owned lots of Fluke TIC's before this one but I must admit I'm loving the resolution of this Talsiman.

[Fraser]

I intend to build one of my BST based Talismans into a new case as well. These units take a beating in their normal role !

You will need to mount the ZnSe lens into some form of rigid holder. I have purchased metal camera lens holders that date back to the 1970's. These come up on e*ay often and make a perfect building block for an auxiliary lens mount.

Be warned, ZnSe is a relatively soft material so can be scratched easily, so treat the lens like plastic lens specticles when cleaning.

Let me know how you get on.

[Henning]

Hi guys,

I have also two of the ISG (here in Germany sold by Draeger) Talisman thermal imagers.

They work with another type of sensor, not the vidicon tube.
This one also has a shutter wheel, and is cooled by a peltier element with a fan attached.



It has a 2.4GHz video transmitter, and a video camera, but no magnification or temperature reading.

You can see the whole thing open here:

http://bit.ly/1SAE0Gb

[Fraser]

@Henning,

Thanks for the pictures of your ISG Talisman.

The unit you have is the successor to the Talisman classic that used the Pyro-vidicon tube. It contains a BST detector array that uses a spinning shutter wheel to refresh the detector elements at IIRC 30fps. The BST detector 'sees' change rather than static temperature and needs the wheel to create such synchronised change.

BST was a very good technology but, like so many other products, the microbolometer won out on simplicity and greater investment by the US military.

I own one original Pyro-Vidicon Talisman and five of the much later BST cored WASP models which appear very similar to your unit but with a later case design.

I contacted ISG regarding the Talisman schematics and they tried to help. Sadly the classic Talisman is so old that the schematics have been lost over the years. The later BST based cameras are covered by the ITAR regulations due to the performance of the detector assembly.

Via my helpful contact in the industry I can advise that the ISG products are similar electronic design to that produced by EEV. The two were past partners  The BST detector core is a Raytheon product (hence ITAR regulations) and is a complete operational thermal camera in itself, with analogue video output. The control lines from this self contained Raytheon camera are married to a third party microprocessor board to provide the functionality that the OEM desires.  Even if the third party microprocessor board fails, the Raytheon camera is still usable on its own

The schematics for the BST equipped Talismans are not available to the public and I do not have access to them. They are protected under ITAR so ISG cannot supply any internal technical information.

IMHO, the Talisman is not the greatest build quality with its very DIY appearance inside. The EEV ARGUS 1 (Pyro Vidicon) and ARGUS 2 (BST)  of the same period are far superior in terms of build. I own several ARGUS 1 and 2 units as well. The Talisman saw service throughout the world and appears to have performed well in its role.

Aurora

[Fraser]

@Henning,

I forgot to ask..... what was the cause of the strange dash pattern that is visible on your cameras CRT screen ?

Kind Regards

Aurora

[helius]

Is the battery level indicator processed as a video overlay, or is it scanned by the CRT during vertical refresh to achieve higher brightness? It looks like the latter by the way that it appears broken up scattered over the display. It appears that the circuit to control its vertical deflection is integrating incorrectly.

[Henning]

Hi,

sorry for the late answer, I don't check here very often.

Yes, the strange pattern is the battery status overlay. Somehow it goes all the way over the screen... Maybe some timing issue, Idk...

[Alexander R]

Hello everyone!
As you can see I just logged in for the first time here and searched for some answers. A few are found, one is not:

I just got some Dräger/Drager/Draeger Talisman C series thermal imagers. One is ok so far, but the screens of two of them are flickering. As I am not an electronics guy myself (just can go to my brothers' company and get some help there), I don't want to search for the failure just by myself- I could do too many things wrong.
Basically I understood that most of the internals could be left out if I wanted to re-embed the important parts in another (smaller) case. The cameras so have an external, analog video out, so another screen will be used.
But, if I wanted to keep the whole setup, is there a well known failure that makes the backside screen flickering (0,5Hz to 1Hz approx.)?

Any help would be appreciated. I am German, so I could talk to someone here, too. Of course overseas as well... :-)

Alex

[Fraser]

The chopper wheel that rotates in front of the BST sensor needs to be checked for damage and correct synchronisation. ISG Talisman chopper wheel motors do fail. The symptom being stiffness when turning the shaft. New motors are available, but expensive. Refurbishing the motor bearings is a possibility, but not a simple task.

Without schematics, fault finding on these cameras is not simple.

The power supply circuits are always a good place to start a fault investigation. Ensure or power supply rails are healthy before blaming any other area of the camera electronics for a fault. The video monitor section is just a simple composite video monitor so the composite video signal feeding it may be fed to another monitor to see if the flickering is present. If not, the cameras internal monitor has a fault. If the flickering persists with an external monitor, there is a problem in the in the signalrocessing stages but that is more complex to work on.

These cameras use a Raytheon Core kit that has an ISG video overlay and control system added to it. The core is capable of producing a video signal without the ISG boards. You may with to go looking for the video signal output on the Raytheon core board connector with an oscilloscope and see what the signal looks like at that point on a monitor. If the flickering is present, there is a problem in the Raytheon core section or its power supplies. If no flickering is present, the fault lies in the ISG video processing circuitry.

Fraser

[Spirit532]

New motors are available, but expensive. Refurbishing the motor bearings is a possibility, but not a simple task.

There are no bearings in those motors, they're oil-infused bronze bushings.
However, you don't need to buy that exact motor, since it's a closed loop system. Just find a motor that fits and is capable of producing speeds equal to or higher than the failed one at the same voltage.
A good place to look is old DVD drives - the tray ejection motor is almost certainly going to fit the Raytheon cores.

[Alexander R]

Thank you, guys! Since I am on holidays now (picked the Dräger's up on the way to our island...) I do have only very limited possibilities to check the cameras.
But the two flickering ones have slightly different frequencies when flickering (whoa, what a sentence). So a little lower and differently turning chopper wheel could be a good point... I would try ro make the motors run smooth again. I do have a bunch of Faulhaber, fan motors (brushed and bl) and many other motors availabe.
Someone have the motor size and (min) rpm of the motors needed for this cam?
So the chopper wheels are not synchronized with whatever? Sou said the just have to have high rpm? That should be easy.
Yes, I was planning to connect an external screen as well. Can do that at home. That would be the easiest way so solve the problem, because the cameras will be stripped anyway. Only the analog out is needed (security cams around the house).

[Spirit532]

Someone have the motor size and (min) rpm of the motors needed for this cam?

They're a standard size, but I don't remember the exact dimensions. It's the same size used in cheap toys and CD/DVD drives.
I believe the speed should be around 3000 RPM @ 3V, but it's not a really big issue, see below.

So the chopper wheels are not synchronized with whatever? Sou said the just have to have high rpm? That should be easy.

They are. The wheel itself has a reflective piece(or could be an interrupter slit on your version) that forms a closed speed control loop. The wheel will always run at one speed, which is synchronised with the sensor's readout(it needs to be "reset" by the wheel every frame, because BST sensors only see changes in temperature).

[Fraser]

It should be noted that the chopper wheel motor used in the various Raytheon BST core kits varies depending upon application and the generation of kit.

Two types of motor are common. The Faulhaber compact coreless type and the 'pancake' type commonly found in CD drives to spin the disk. Apparently the Faulhaber motor suffers from angular inertia induced speed variances. The CD drive type motors are better in this respect.

Oilite bearings in the motors can be restored with some effort. I have just copleted such a task on an expensive motor. I used a combination of Acetone, a vacuum chamber, an ultrasonic bath and some W30 weight motor oil. It was not actually very difficult to do. More info if needed.

I do not have a motor to hand but on the similar ARGUS 2 camera it has the motor type marked on it. I shall take a look for details in my data archive and spares boxes.

Fraser

Fraser

[Fraser]

Some information I quickly scraped together on the two motor types used in teh Raytheon core kit.

The Faulhaber coreless motor is a far superior unit that contains precious metal contacts, hence its high cost ! It is fitted with ball bearing races for long life. The CD type motor is a much cheaper affair that uses a cored motor and Oilite bearings.

The Faulhaber motor in the Argus 2 Raytheon core is type 1516T. I forget the voltage marked on it.

The CD type motor is type Mabuchi / Kysan RF-300PA 11400 and rated at 5.9V. It measures 24.35mm x 13.2mm with a 2mm diameter shaft.

Fraser

[Alexander R]

Thanks again to both of you. As soon as I am back fro holidays (don't want to think abount that too much) I will look inside of one of those Dräger's.
Like I said: I am not an eletronics man, but all the mechanical stuff isn't really a problem. I do have a pretty complete workshop with a bunch of CNC machines and to relatively often do interesting jobs in CNCing things for people...
Once I'll get the new 3D printer (TFT/resin type), I can print in 350x250mm... Could be imteresting for new housings of these cams and so on.
Fraser, you don't have to look it up now. I'll try to find out. Let you know in a couple of days, when Itook one of those apart. Aaahh, just seen that you wrote another reply. Thanks!
I know that I have a bunch of Faulhaber motors at home. All geard. But the gearbox can be removed. As long as they only have to spin (in roughly the right rpm) they could do it...

[Fraser]

I just dug out one of my dismantled units to check the motor model and supply some pictures. The unit in these pictures has a failed motor that is quite hard to turn. Gummed up or corroded ball race I suspect.

The motor used in your Talisman is a Faulhaber 1516T012S so it is the 12V version.

Some pictures for you .....


Fraser

[Fraser]

While I had the chassis on the table, I thought some pictures of the main PCB's might be of interest.

In this set of pictures, the upper board is the ISG designed control PCB and the lower board id the Raytheon designed core PCB that is provided in the core kit. The PCB's are held in place by aluminium end plates and RTV to provide further security for the connectors.

At the rear of the chassis there is the power board and the PCB 'backplane' sits at the other end.

Fraser

[Fraser]

PCB detail.....

ISG PCB first.....

Lots of unpopulated pads on this PCB. The board is populated as required for different camera models and capabilities.

Fraser

[Fraser]

Now the Raytheon PCB .......