(new pic posted, please help) Cairns Viper, self-heating, some other questions

[Logan]

Hi guys.

I just got a Cairns Viper, now I have a few questions about it...

Q1. It close/open the shutter 4 cycles on every power on, is it normal?

Q2. It works well until it heat up, here's the time line in my test:

Start up.
~1 min: First NUC after boot, begin to show slight white pixels.
~8 min: The right side of the image begin to darken to a noticeable level(and growing).
~25 min: While the shadow becoming darker and wider, there begin to have white line on the right edge(FFC want to correct that)(growing thicker with each shutter action).
~41 min: I power cycled the device and the picture is very foggy, until the next NUC.
~56 min: The high-temperature warning icon shows up(see pic 1).
~1h 5 min: The black shadow and white area become much thicker(shadow is also darker), the temperature bar become full(1000 F)(see pic2)
~1h 11 min: Battery died.

There are also some other random behavior when over heating:
a. Sometimes the temperature bar shows 300 F(see pic 3).
b. Sometimes when power on while hot, there's a red symbol next to the battery, in this mode, the shutter will never trigger(see pic 4).

When I take out the "super cool" metal block, it's super hot. Is that a normal thing for old TICs? My friend's BST camera doesn't seem to have this problem.

Q3. What's the red symbol in pic4 means?

Thank you!

[Fraser]

In a fire camera the temperature warning cam be indicating that the camera is operating in an environment that is too hot fir it to cope with and should be moved to a cooler location. That ambient temperature is measured by a sensor within the camera. If this is the case with your Viper, the over temperature alarm is actually detecting a completely different situation…. A fault within the camera is generating enough thermal energy to overheat the core ! Not a food situation. If the cooling block comes out feeling hot, that seems wrong to me but Bill_W may know more. I understood that the cooling block was intended to act as a heat soak away for the camera whilst the ambient temperature is high in order to prolong operational capability.

You would be wise to open the camera and carry out some testing to determine the source of the internal heating in case it is a fault and could cause further damage. It could be power supply related so check battery temperature and power supply temperature first. I have not worked on a Vioer so sadly cannot help much regarding its internal design. Look into the heating situation before worrying about other fault symptoms as they may stem from the cause of the self heating.

Fraser

[Fraser]

This thread from 2018 may also be of interest…

https://www.eevblog.com/forum/thermal-imaging/carins-viper/

[Fraser]

From Bill_W’s fire-tics site….

http://www.fire-tics.co.uk/others/cairns_viper.pdf

[Logan]

Thank you very much Fraser!
So it's not normal? Okay I'll try to fix it...
I did searched the forum and found those threads, but nobody talk about the heating problem.

Look into the heating situation before worrying about other fault symptoms as they may stem from the cause of the self heating.

I know, I just think it's interesting to document it's mad behavior.

[Fraser]

Microbolomter based Thermal cameras need an ambient and FFC shutter temperature reference in order to correctly report a targets temperature. If the internal ambient temperature rises too high it can mess up the measurement function. Increased internal temperature can also cause uneven heating of the microbolometer via adjacent heat source conduction, convection or radiation. If there is an abnormal heat source near to the microbolometer it has the potential to cause all manner of havoc with the displayed thermal scene. If looking for a heat source adjacent to a microbolometer using the effect seen on the display, remember that some cameras use inverting optics so the microbolometer is mounted upside down so left is right and up is down in the displayed image.

Fraser

[Fraser]

Regarding the red symbol next to the battery. That is a classic battery over temperature warning. From memory the Viper uses Lithium Polymer cells and if this is the case, they are not supposed to be exposed to temperatures greater than 60C to avoid self destruction ! Many camera systems monitor the batteries internal temperature during charging and even discharging (in the case of fire fighting cameras) so that the user may be warned if the battery is getting too hot.

As we are potentially dealing with a failed Lithium cell filled battery, I advise great caution whilst charging or using the battery and DO NOT store that battery pack inside your home without it being in a fire resistant container. A lithium battery pack can suffer cell deterioration and there is the potential for cells to overheat for several reasons. Normally the battery contains temperature monitoring, self resetting temperature breaker and a non-resetting (permanent) thermal fuse. Your battery could potentially be getting hot, but not hot enough to trigger the breaker or thermal fuse. Alternatively, something inside the camera is heating the battery either via external heating of the pack or overload due to excess current draw. All worth investigating but please do be careful if you are dealing with elderly Lithoum Polymer cells….. they can be a real fire hazard which is kind of crazy ironic when you think what they are being used in here ! 

Fraser

[Fraser]

Just looking at the Viper brochure, I see that it does indeed contain a Lithium battery pack. This pack is located next to the cool block and you have already stated that the cool block gets toastie hot. This could be heating the battery pack causing the battery temperature alarm. Your test lasted just over an hour before battery discharge and the original duration specification is only around 90 minutes so it does not sound like a serious over current situation causing battery heating. That said, we cannot discount the battery self heating during use so caution is advised.

Take a look inside the camera and see where the heat has been transferred from that us causing the cool block to get so hot. If the cool block is thermally bonded to the cameras chassis, what else is bonded to that chassis that can generate so much heat ? You could use another thermal camera to monitor the camera when first switched on to see the locality of any internal heat source. Then remove the covers and check again to determine the cause of the internal heating.

Fraser

[Logan]

Thank you so much Fraser.
I opened the camera, and since my Seek is broken, I just use my finger to test...
The heat seems come from the processing board, the Xilinx chip is the hottest I can reach, there are some other things like Intel Strong ARM mounted on the other side, but I cannot reach them, because there's a power board stacked close to that side.
The camera works better with case opened, and the battery or microbolometer is not that hot, so I assume they are not the heat source.
By the way, the whole block look like this from side:
|------
|------
The left is the sensor and it's board(please ignore the space, there's only one), while 2 horizontal boards are power board and processing board.

[Bill W]

If you can unplug the battery and run from a power supply that will tell us a lot.

A 320 temperature-stable VOX is a pretty hungry beast so expect around 3A at least for up to a minute or so.  May be worse as I think that was an earlier core in the Viper than the Lockheed 205 in Argus3(orange-VOx)

Just guessing but if the thermal control loop was opened (as simple as a thermistor fallen off) the core control might be in a runaway 'I must get colder' mode flat out which could explain several of your observations.  When open it might hold under the 30°C set point so not run away

The thermometer was usually set up to warn of high detector temperature (so only a consequnce of the ambients) and to encourage the user to turn off before damaging it, or to give some warning if the camera turned itself off for protection.  It was generally assumed that a 5 minute warning was enough for the firefighter to get to a safer location similar logic to their air supply.

[Fraser]

As usual Bill, you have great insight  If the TEC is running hard to cool the microbolometer due to a loop failure, that would certainly generate lots of excess heat within the camera. The reasonably good run time is better than I would have expected though as the Peltier module is power hungry. You could well be onto something though  As you say the current draw behaviour could tell us a lot.

Fraser

[Logan]

Thank you Fraser and Bill.
I actually thought of the TEC feedback failure before, but didn't know how to check it, good point to check the current.
But I may not be able to do that recently, I will report back after test.
By the way, Does anyone have the document for the core? it would be interesting to see.

[Logan]

Hi, while still waiting for my multimeter to be repaired, I disassembled the camera again and found the wires appears to be connected to the TEC. I ran the camera with TEC unpowered, the camera warned for temperature immediately after boot, and the picture quickly shows sensor artifacts which is inverted compared to the condition with TEC.
So I think our guess is corrent, the TEC keeped cooling the sensor despite it's already colder than normal.
If that's the case, how can I fix it? Thanks.

[Bill W]

I suspect some of these thoughts may not be much help, but here goes:

What is the sensor involved, how should it work ?
Is it giving the expected output for ambient + 7 degrees ?
Can it be disconnected from the camera - and is it then OK. Hopefully, otherwise it is in the sensor itself.
If you briefly reconnect the peltier (or power it independently)  does the sensor change in the right way ?

A pure guess is that the sensor die should sit at 30°C, purely as all other sensors did, so again if powered independently adjust for no artefacts and you should be at the setpoint.  That should then tie up with however they did the Peltier control.  Hopefully follow the drive back and find a specialist Peltier IC and cross reference data sheets.  It might however be buried inside software so more difficult to check.

Seems the temperature warning is an 'out of limits' not an 'overheat imminent' as I proposed above, although the user logic is probably the same - turn me off before you get to invoke the warranty.

[Fraser]

The TEC circuit is closed loop so you will have a temperature sensor mounted inside the microbolometer module, on the die, and this feeds it’s signal to a TEC controller IC that manages the Peltier module that sits on the rear of the microbolometer die, but within the vacuum of the microbolometer module. Neither the temperature sensor, nor the Peltier module may be accessed for repair so let us hope these are serviceable.

The temperature sensor on the microbolometer die would usually be a thermistor but a diode is another possibility. The sensor changes it’s output in response to temperature so it should be possible to monitor the temperature sensor output pin or the pin on the TEC controller that it connects to. TEC controllers should be relatively easy to identify by device number and they usually have pretty heavy duty PCB tracks around them for the Peltier module that draws between 1A and 3A at first start from cold. The TEC and associated Peltier module is used to warm the microbolometer to around 30C and to then hold it stable at this temperature. You should see the signal at the temperature sensor input change as the microbolometer warms up and then a slow sinusoidal variation will be seen as the temperature is maintained at a nominal 30C. The Peltier module drive from the TEC can take several forms so check the datasheet for the IC. Common drive methods for a Peltier temperature stabiliser are variable voltage/current, PWM or on/off switching. On/Off switching is the most crude and least desirable drive method as it can stress the Peltier module. PWM gives excellent control over the Peltier modules heating and cooling behaviour. Varying a DC voltage or current will control a Peltier module but PWM is often preferred.

You need to look at what is happening at the input to the TEC controller and what the TEC is doing at its output in response. The TEC may contain its own internal Peltier element drive circuit or it may use external components / driver IC instead. If an external driver is used, you will need to check its output to see whether it correctly reflects what the TEC wants it to do. You could be in a situation where the TEC drive to the Peltier uses a transistor H bridge that has become shorted so the drive is continuous instead of PWM or variable voltage/current.

Your camera appears to be excessively cooling the microbolometer as that produces excess heat at the Peltier elements heatsink face that is attached to the rear of the microbolometer module. That state is unusual as the TEC normally heats the microbolometer die and does not actively cool it unless the ambient temperature is above ~30C. You need to examine the behaviour of the TEC IC to determine exactly what is happening and why. The likely faults are : die temperature sensor wiring to the TEC chip, TEC output driver failure or TEC IC failure. The TEC will be configured in some way to set an operating temperature and that part of its circuit would be worth checking in case there is a faulty component present. The TEC IC datasheet will likely provide a sample circuit that closely resembles that used in your camera.

Thankfully the failure of the ‘on die’ temperature sensor is unlikely and we can see a change in behaviour when the Peltier module is disconnected, so hopefully the Peltier module is also serviceable.

Hope this helps

Fraser

[Fraser]

The datasheet for the well known LTC1923 TEC IC is linked below. This will give you a feel for what a dedicated TEC IC offers and how it is configured to drive a Peltier module. Note the external H bridge drive transistors.

https://www.analog.com/media/en/technical-documentation/data-sheets/1923f.pdf

[Fraser]

Please provide some nice clear pictures of the cameras PCB’s so that we can see the chipset used and as a future reference 

Fraser

[Logan]

Please provide some nice clear pictures of the cameras PCB’s so that we can see the chipset used and as a future reference 
Fraser

Okay, 8 7 in total.
Other 4 battery related photos: https://www.eevblog.com/forum/projects/how-to-make-this-device-think-it-have-a-battery/
Because of "maximum total size 5000KB" forum limit, there will be several posts.

[Logan]

...

[Logan]

...

[Logan]

Picture 7,8 are the back of the sensor board, I cannot take it off to have a full view because the screws are too tight (and my screw driver seems a little bit too big). Full back photo taken, See post below.
Picture 5 shows the lens and shutter assembly, different from the metal one in the forum(and only have 2 screws on the 4 screw holes), they are cutting corners?
Picture 3 shows a 3-pin plug on the right-bottom corner, it's just unplugged as I first open it, why?
Forget it, there are too many unused sockets as well.

[Bill W]

As the designer seems to be a fan of Analog devices, maybe there is an ADN8831/33/34 in there as the Peltier control ?

Bill

[Fraser]

Sadly none of the IC part numbers that I can read are a TEC controller so it is either the one I cannot read on the Microbolometer PCB (picture 5, top left corner square IC) or it is not visible in the images.

Fraser

[dertoid]

I love my CairnsViper (correct name).
Do you have full kit in a case? You should have spare thermal sponge - piece of metal. When cam starts to heat up you just pull hot one out then swap with spare one.

[Logan]

Sadly none of the IC part numbers that I can read are a TEC controller so it is either the one I cannot read on the Microbolometer PCB (picture 5, top left corner square IC) or it is not visible in the images.

Fraser

I finally take the full picture of the sensor board back. Now all PCBs (except the LCD one) is here.

[Logan]

I love my CairnsViper (correct name).
Do you have full kit in a case? You should have spare thermal sponge - piece of metal. When cam starts to heat up you just pull hot one out then swap with spare one.

I don't have a spare one...
So you also have the same model? Do you have the similar problem?

[Fraser]

If required, spare blocks are available here at $29.95 ……

https://www.ebay.co.uk/itm/380698382876

Fraser

[Logan]

If required, spare blocks are available here at $29.95 ……

https://www.ebay.co.uk/itm/380698382876

Fraser

I don't think that will solve my problem anyway.

I tested the camera without TEC, the sensor artifacts are much lower than with TEC. However I found a new problem: if the camera is run upside-down for sometime, the screen will out-of-sync, just like the attached photo . (It's actually moving horizontally very fast, not static).

[Fraser]

A microbolometer will often reach thermal equilibrium at around 30c to 32C but it will not remain stable at a particular temperature, especially if the ambient temperature changes. This is ten way many modern thermal imaging cameras operate ( no temperature stabilisation) but they use offset tables to correct for temperature drift.

[Fraser]

With the TEC disconnected does the camera run at a more reasonable temperature ?

[Logan]

With the TEC disconnected does the camera run at a more reasonable temperature ?

It's still feel hot to me, but the battery last somehow longer(1h 23min).

[Logan]

It's a bit strange why the high temperature warning shows immediately with TEC disconnected. It's only 2 wires, is it somehow monitoring the temperature while powering the TEC?

What's the red symbol in pic4 means?

I found the answer, it's the low sensitivity mode indicator, it shows up when I point at a solder iron.

[Fraser]

On your microbolometer PCB you can see what appears a bipolar transistor H bridge for driving the Peltier element. The op amp (U10) between them is likely the driver so you need to look for the source of signals to that op-amp to find the TEC controller. It is possible that the TEC controller monitors current draw to the Peltier element so if you disconnect it, an alarm function may be activated. A thermal camera used in safety situations needs to warn the user if a defect exists.

https://www.analog.com/media/en/technical-documentation/data-sheets/OP295_495.pdf

Your battery will last longer with the Peltier module disconnected as Peltier elements are power hungry beasts ! One of the reasons why Peltier temperature stabilisation has been left out of some modern microbolometer camera designs is the desire to reduce power consumption.

[Fraser]

Can you provide the details of what is written on the IC that I have highlighted please. It may be the TIC controller.

[Logan]

Can you provide the details of what is written on the IC that I have highlighted please. It may be the TIC controller.

Hi Fraser, it's as below:
H12315JCQ
341A58V
Hope it is, it would be a nightmare to track connections on such a multi layer board.
Thank you so much for continuous help.

[Fraser]

I suspect it is in fact the HARRIS HI2135 and the second character is an "I" and not a "1".

Data sheet attached.

Sadly it does not help as that is a 80msps high speed D to A converter.

I will revisit this later as I have a date with the underside of my wifes car.

Fraser

[Logan]

With the TEC disconnected does the camera run at a more reasonable temperature ?

It's still feel hot to me, but the battery last somehow longer(1h 23min).

I'm just thinking, is it possible that the TEC is fine, but as the excessive heat is generated, it lost control?
Or even more, the camera is not malfunctioning, it just need to change the metal thing once a while?
I'm still waiting for @dertoid to tell me...

[Fraser]

Sorry I do not know as I have not used this camera and do not have access to a user manual.

The current draw of the camera will tell you more about what is going on with the camera. It will draw higher current at start as the microbolometer warms up with the help of the Peltier element. Once at operating temperature the current draw will reduce to that needed to maintain the microbolometer at operating temperature. If you see the current steadily increasing after this point it indicates that the TEC controller is having to nor’easter drive to the Peltier element to counter heating from around the microbolometer.
If the current draw at start is high and does not drop back to a reasonable value once the microbolometer is at operating temperature, there is a problem with the temperature stabilisation circuit.

Fraser

[Bill W]

The metal brick should last a good 30 minutes even with the camera in a hot place, so for ambient I'd expect it to outlast the battery run time.

Only issue would be if the brick had become thermally disconnected from the peltier, then the hot side of the peltier would get VERY hot and bring the sensor up with it, so again increasing the power - vicious circle.

Bill

[Ultrapurple]

I have been following this with interest. Are you able to measure the voltage across the TEC? That would be a direct way of seeing what's happening (and very similar to the current measurement suggested by Fraser). As with the current, I'd expect to see the voltage start off high (~battery voltage) and after a minute or so reduce to a lower level. This assumes linear control; in the relatively unlikely event that it's controlled by PWM you should still see something change when the TEC gets the sensor up to temperature.

[Logan]

Thank you everyone. It's like lost an arm when I send my multimeter for RMA. I'll report back as soon as I got the measurement result.

[Fraser]

Always have a spare multimeter Even a really cheap Harbor Freight one is a good backup 

Fraser

[Logan]

Hi guys.
I borrowed a low-quality multimeter and use an USB adapter (5v regulated) as power source, then did a very rough test 
The Viper draws about 1.9A without TEC.
With TEC, it draws about 2A just after cold start, then slowly increase to 2.2A after a few minutes warming up, which is the USB power adapter limit. At this point, the picture begin to distort and I cannot even reboot the camera with TEC. If I power the camera on without TEC, then connect TEC, picture and function indicator instantly messed up.
I will do a better test after got a proper power source and meter 
Thanks.

[Fraser]

Sadly using such a current limited power supply is likely to cause you problems as you have experienced.This generation of microbolometer thermal camera draws a fair amount of current at initial power on and the power supply needs to cope with that without lowering the output voltage in response to hitting its maximum current capability. I advise a 3A power supply in most cases to cope with peak current events.

Now to your readings…. I am surprised to see a 1.9A current draw with no TEC in circuit. I would expect less than 1A and more like 0.5A for such a camera. Sadly I have no specifications to hand but you should be able to work out the average current draw from the stated normal operation time on the battery and the batteries stated capacity. Even with the TEC in operation the calculated current draw will be useful.

I do not know your circumstances but if you can  save some funds to buy a new or used variable power supply capable of 15V at 3A you will find it very useful when working with electronics projects and thermal cameras. Well worth the investment and you do not need to buy something high end and expensive. A budget unit from Amazon or EBay will be adequate. Make sure it has both variable voltage and current though. You can use such a power supply to charge batteries at a set current which is useful as well. If you were located in the UK I would gift you such a power supply as you are clearly interested in working on equipment and display “the right stuff” to deserve help.  Maybe someone in the USA can assist with a power supply donation to your projects work ?

Fraser

[Fraser]

I just checked the official run time for the Viper from its battery pack. It is 90 minutes. If you are seeing a non TEC current draw of 1.9A that suggests the battery pack has a capacity of at least 3Ah and more if the TEC current draw is considered. What does your battery pack state in terms of Ah capacity please. If there is no specification on it, please provide a picture of the battery with a ruler for scale so I can assess whether it likely contains multiple cells and how many.

Fraser

[Logan]

Thank you Fraser!
I don't need donation, thanks for the offer
There's no spec for (m)AH visible on the battery.
Here is a disassembled battery photo, sadly it's too blur and I threw away the cells... There were 6 cells, 3px2s arrangement.
The battery pack P/N is 53-1500.
The cell part number is too blur, if you do need that info, I may disassemble another good battery to get the cell part No.
Thanks.

[Fraser]

I recognise those rectangular Li-Ion cells. I should be able to guesstimate their capacity from others I have seen from that era. From memory they had a capacity of 1.0Ah to 1.5Ah per cell. So three in parallel gives a capacity of 3Ah to 4.5Ah (depending upon capacity of cell used) which with a 90 minute run time gives a nominal current draw of 2A or as much as 3A if the higher capacity cells were used. That Viper is a power hungry beast !

There were issues with the Cairns Viper batteries and they went through three generations of battery to find one that actually provided the expected run time and service life. I have read complaints of cameras only running for 30 minutes and batteries not wanting to charge. It seems Cairns had some problems with the li-Ion technology that was available in that era. These metal block cells were used in Motorola Flip phones and were known to suffer “cell bulge” when failing. Most cells of this era are long dead so you did well to get rid of them. I replaced such a cell in a Guide RazIR thermal camera with a modern Canon digital camera battery that was around $6 on eBay. Sadly that battery contains a protection PCB so you will need to look at other sources of replacement cell or use an external battery pack. Li-Ion cells can be quite expensive and care is needed if you think of using cheaper Li-Polymer cells as they have slightly different needs to Li-Ion when it comes to charging.

[Fraser]

Post 14 of my Guide RazIR teardown shows the Li-Ion block cell used in its battery pack. To my eyes it looks like your Viper cells are smaller so most likely nearer to 1Ah rated. The RazIR contained a 1.55Ah cell.

https://www.eevblog.com/forum/thermal-imaging/spi-razir-mini-thermal-camera-teardown-and-comment/

As such I would expect your camera to draw around 2A from a 7.4 V (6.6V min / 8.4V max) supply. Your 5V USB was insufficient in terms of both voltage and current so the current draw of the camera may have been excessive due to the action of DC-DC converters trying to maintain their output voltage.

[Logan]

Thanks Fraser.
Battery is actually another problem for me: https://www.eevblog.com/forum/projects/how-to-make-this-device-think-it-have-a-battery/
 

[Fraser]

The bq2050 is thankfully quite an old and relatively simple gas gauge IC. You may find that just attaching a pair of Li-Ion 18650 cells to the three battery pads on the battery PCB will allow the bq2050 to fire up and the battery to be recognised by the Viper. The bq2050 may be reset as detailed in the data sheet (page 4) by removing VCC and shorting RBI to 0V for 15 Seconds. Worse case scenario, you will need to connect to the bq2050 using a laptop equipped with SMBus interface and TI software. You may then be able to reconfigure the IC to operate again. Battery gas gauge IC’s can be challenge when it comes to rebuilding a battery pack but hopefully this one is old and simple enough to be happy with new cells fitted. There may ne an issue with cell capacity but try to get the pack working before worrying about that issue.

https://www.ti.com/lit/ds/symlink/bq2050.pdf?ts=1633021154583&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ2050

Fraser

[Logan]

Thank you Fraser!
I do have another working battery, I ask that question was because I don't want to use the original battery pack.
I actually just found the manual about the same time as you
It seems the "signal" pin on the battery is actually using a protocol to communicate with the camera (instead of some kind of simple analog signal), also the bq2050 is actually monitoring the battery in/out current (instead of just voltage).
So I think there's no way around that, unless I can mess with the host firmware which I can't, I have to live with the annoying huge flashing warning sign if I don't use the original battery pack.
I hate this design 

[Bill W]

All you need is a battery pack with a BQ2050 in it - or maybe just something that responds like a BQ2050 would.

You'd need a scope to see what goes back and forward over the DQ pin.

This looks very like the ancient BQ2010 protocol and the device updated for lithium cells.  As such the datasheet for the BQ2010 (and its' evaluation board) may be better explained and give you a few more ideas.  Not so sure something as 'new' as SMBus would be able to cope.

I'd expect (based on the BQ2010 - as per Argus2 and Argus4) that the camera sends a read of (REGx) and collects the return data to display battery state.
If you think it would help I have the BQ2010 low level software (DOS) to send read commands and display the response, and the EV2010 kit has the circuit to turn DQ into RS232.

Bill

[Fraser]

Bill_W,

Thanks for the correction on the communications port type on this early gas gauge  Another that uses that DOS program with fussy serial port timing ! Thankfully the required interface is simple though I bought the versatile Texas Instruments EV2400 interface for SMBus communications with gas gauges but sadly most I have tried (from more recent battery packs) are protected by a password and require a custom (Manufacturer controlled) version of the software, so battery re-celling becomes a real challenge At least with the bq2010 and bq2050 you have a chance of succeeding

Fraser

[Logan]

Thank you Bill and Fraser.
I know I can replace the cell in the old battery, but I want to be able to power it from a DC supply without warning.
Maybe I should look for the direct output from the core later, but now I would just solve the heating problem first.
 

[Fraser]

You need to spoof the cameras battery monitor into thinking it has a battery fitted, as Bill has suggested. The battery monitoring firmware will expect a response from a bq2050 on it’s data line. To my mind, there are two ways to do this….either build a small microcontroller board that mimics the bq2050 in terms of challenge and response, or a simpler approach would be to rebuild a battery pack to satisfy the cameras firmware that such is present and then provide another power feed to the camera so that the battery is not actually providing the camera power and remains charged. This idea would be simpler but would need some thought.

Basically you need the camera to see a valid data output from what it thinks is a bq2050 gas gauge, even if in the real world it is a spoof or ‘dummy’ containing two small Lithium cells to power just the bq2050.

And remember, your working battery will be on borrowed time now so it is worth looking at rebuild options for that pack as well.

Fraser

[Bill W]

Bill_W,

Thanks for the correction on the communications port type on this early gas gauge  Another that uses that DOS program with fussy serial port timing ! Thankfully the required interface is simple though

The pure DOS program (ap10a.exe) - is a straight boot to DOS and it is purely a command line, and seems OK on any PC with a serial port.

It is the 'nicer' one (EV2010.exe) that we have been trying to get going on old windows PC's.  ev2010.exe would not be any good for Logan and the BQ2050

regards
Bill

[Bill W]

The 2050 had an evaluation kit - and sounds the same as the BQ2010

https://www.ti.com/lit/ug/sluu040/sluu040.pdf

note the warning:
The EV2050 uses the PC-AT real-time clock to provide
the proper bit timing for serial communication with the
bq2050. The modem control lines are used as the
single-wire serial interface to the bq2050. Any TSR that
uses the PC real-time clock affects the operation of the
EV2050. For proper operation, the EV2050 should not
be operated from a DOS shell program


Not been able to find the software though.

Bill

[Logan]

Thank you guys.
I finally got my multimeter and did the test.
I don't have a suitable power supply yet, so I use the one in the Cairns charger, rated 12v 3.3A, with a knob on the board, I set it to 11.6v. It's regulated very well, voltage not changing even 0.01v with variable load. I took the risk of burn the camera, but it didn't , so the camera surprisingly can work 5-11.6v at least.

TEST LOG:
Boot up
0 min: 0.75A/8.7W
10 min: 0.81A/9.4W
16 min: 0.86A/10W, white line begin to appears in picture
21 min: 0.92A/10.7W
30 min: 1.03A/11.9W
35 min: 1.11A/12.9W, NUC can no longer maintain uniformity, large foggy area appears
40 min: 1.16A/13.5W, temperature warning icon appears, current reading stop increasing
50 min: 1.16A/13.5W
Torture Test ended.
(The current value is for the whole camera)

More information: The suspected TEC header is 2-pin, 6.1v regulated(no matter the main power voltage, temperature, or load). I don't know if it supposed to be so. Seems like the controlling part is on the sensor board, or maybe mine is malfunctioning.
Any ideas?

[Bill W]

That is a flat out Peltier.  Should be down to around 5W by no more than 3 minutes.

Pull the Peltier header and see what the current is.

The current rises a bit as the Peltier gets hot, the 6.1V regardless is the Peltier controller power supply maximum voltage.

Ok, so the mystery now is why ......... 

Bill

[Logan]

That is a flat out Peltier.  Should be down to around 5W by no more than 3 minutes.

Pull the Peltier header and see what the current is.

The current rises a bit as the Peltier gets hot, the 6.1V regardless is the Peltier controller power supply maximum voltage.

Ok, so the mystery now is why ......... 

Bill

Without TEC and under same 11.6V, the current is 0.67A,(7.8W), and remain unchanged in the 10-min test.

[Fraser]

This document may be of interest. Note the comment on thermal runaway but I do not think we are seeing that here.

https://www.teamwavelength.com/download/applicationtechnotes/an-tc09.pdf

For the heatsink to be getting hotter and the current drive to the Peltier element to be max’d out you are seeing a failure in correct temperature reporting from the microbolomter, a failure in the TEC or its output Peltier driver H bridge. If the TEC is working and it’s Peltier driver is OK, then the sensor circuit providing the temperature of the microbolometer must be reporting an erroneous higher temperature than the nominal ~30C . The TEC is desperately trying to cool that microbolomter and by the looks of the symptoms the Peltier is managing to get that microbolomter very cold, too cold to operate correctly in fact. You can view the Microbolometer die temperature by looking at it through the microbolometer window with another thermal camera. An IR thermometer will also work if held up against the window. If the temperature sensor circuit fault is suspected, look and test for connectivity failures in the circuit and monitor the TEC behaviour as previously discussed. Sadly you cannot just guess at the fault in a closed loop system due to interactions between the component parts of such.

[Fraser]

I just had a thought, is it physically possible to accidentally reverse the polarity of the wires going to the Peltier element of the microbolometer ? I ask because such a polarity reversal does no actual harm but the following occurs….

Microbolometer temperature sensor ‘reports’ that the die is below ~30C.
The TEC needs to warm the microbolometer a little with the Peltier element so applies a heating drive polarity to it.
Because of the Peltier wiring reversal, the Peltier would actually be driven into cooling mode and cools the microbolomter !
The die temperature sensor keeps telling the TEC that the die temperature is too low so the TEC keeps applying what should be heating via the Peltier element.
The reversed Peltier wiring keeps using the TEC  drive current to cool the microbolometer die and it has no hope of ever reaching +30C but, instead, likely drops to -10C or so ! The microbolometer would be so far out of its ‘comfort zone’ that it would not operate correctly. The poor TEC would continue to command heating but would in fact be causing cooling !

Just a thought and worth checking maybe ?

[Fraser]

In case anyone is wondering how a connectors polarity can end up reversed….some cameras are sent for repair, declared B.E.R., and effectively scrapped. If reassembled as a scrap unit connectors may, or may not be correctly fitted by the tech. I would argue that the camera should leave in the same, or better condition than it arrived in at the service facility but people can get lazy if a unit is declared B.E.R.

These Viper cameras were not known for their reliability and some spent a lot of their lives in service centres being repaired. There appears to be a video related fault on this particular camera so it may have gone in for  that issue but come out with B.E.R notice and an additional fault created during investigation/reassembly. All conjecture on my part thought.

[Logan]

Hi Fraser.
I just watched the sensor rapidly cool down with TEC. We were correct, it's cooling down as soon as power up.
I found another 3-pin temperature sensor glued on the metal frame, it seems change resistance with temperature, but seems affect nothing, even I unplug it, there's no warning.
About the polarity reverse, it seems impossible, because the plug on both side is fool-proof, thus cannot insert reversed.
Thank you.

[Logan]

Err, I just saw your last post.
So that's why it looks so homemade?
Many loose or fragile wires(I already have to rewire a couple), strange patches on cables, some unused wires or pins... Maybe some are just by design...
So should I just invert the TEC header and power on to test? Will it have risk of damage something?

[Bill W]

Err, I just saw your last post.
So that's why it looks so homemade?
Many loose or fragile wires(I already have to rewire a couple), some unused wires or pins... Maybe some are just by design...
So should I just invert the TEC header and power on to test? Will it have risk of damage something?

Only if very careful and as a last resort.  I would find a way to just touch the Peltier on in reverse and see if it stabilises or runs riot again.  The problem is that the 'hot' side gets hotter a lot faster than the cold side as it has pump energy plus dissipation going into it, and it will only be the sensor die to take that power not a heatsink.

Someone did that on a ULIS sensor and it was never the same again.  It did however nearly double the sensitivity !

Bill

[Logan]

It did however nearly double the sensitivity !

Seriously? How?
Okay I'm doing it now.

[Logan]

No, it doesn't work.
The camera don't boot with TEC wire inverted, the 6.1v pins stay at 0.27v, seems like a short circuit.
Maybe the controlling system is indeed on the sensor board, and the 6.1v pins is just power.

[Fraser]

In this situation I would definitely begin reverse engineering of the TEC controller circuit to establish the location of key components and suitable test points. Such reverse engineering has been detailed previously on this forum but basically your need to build a ‘net’ of component interconnections. This is done both visibly and by continuity checks across the PCB. There are tricks to aid the continuity checks such as losing one probe on one ‘node’ and browsing the PCB for continuity with that node using the other probe tip or attaching the other probe to your finger with aluminium foil wrapped around it to create a broad probe head. I use an excellent Wavetek short finder that has a steel brush and a pointed probe for continuity checking. It is fast and effective. Basic reverse engineering is sadly an essential skill when repairing many thermal imaging cameras as there are no schematics available for this technology.

Fraser

[Fraser]

The short finder thread……

https://www.eevblog.com/forum/testgear/wavetek-sf10-short-finder-a-very-useful-tool-if-you-can-find-it/

[Fraser]

Thread detailing reverse engineering of PCB’s, including comments from me on the topic.

https://www.eevblog.com/forum/eda/pcb-reverse-engineering/

Fraser

[Bill W]

Maybe the controlling system is indeed on the sensor board, and the 6.1v pins is just power.

The 6.1V is some power rail (maybe 7V ?) less the saturation of the H bridge driver transistors and maybe a series resistor for current measurement.

Looking closely at the image where Fraser noted them, seems a bit suspect that the bottom two are legible and the top two might look a bit cooked ?
Not necessarily a cause, likely still just an effect.  Scope or DMM all pins on that op amp.

[Bill W]

It did however nearly double the sensitivity !

Seriously? How?
Okay I'm doing it now.

It did indeed, we never knew why but that Ulis 03191 A-Si was known as 'Christine's magic sensor', must see if it ended up in the 'scrap'  .  It was too weird to calibrate normally.
It was run for a good hour or two and was down to a short on the temperature feedback voltage making the sensor seem 'too cold'. 

The heat may have cooked the pixels or die amplifiers or perhaps done a bit of extra gettering.  But it was a stand-out image.

Bill

[Logan]

In this situation I would definitely begin reverse engineering of the TEC controller circuit to establish the location of key components and suitable test points.

Thank you. But I have never done such thing before, I will try to do it later and report back.

[Logan]

Scope or DMM all pins on that op amp.

I don't have a scope... How should I DMM the pins? I guess test the resistance to GND when power off, and voltage to GND when power on?

[Bill W]

Voltages with and without the peltier connected.  Resistance likely less interesting.

The idea is to work back until we find where the output of a bit of circuit is no longer reasonable when compared to the input.
The important thought is that 'garbage out' is OK if it is correct for a given 'garbage in'.

The circuit operating principles will be along the lines of any Peltier drive IC even if built from discretes, maybe a micro, and (op-amp+TR) instead of the mosfets.

Maybe see how much of this is in there:
http://www.anderswallin.net/2013/08/tec-drive-prototype/
http://www.anderswallin.net/wp-content/uploads/2013/08/sbea001_tec-drive_v3.png

There will be a comparator (or high gain op-amp) to compare the reference to the sensor temperature feedback
There will be an integrator
You already have the output drive stage (opamp and 4 transistor)


Bill

[Logan]

Here's the raw test result for the OP295 on the back of the sensor board:

No TEC, just on
45
154
978
7
10
167
749
350

No TEC, 15min
56
154
972
6
9
166
740
349

TEC on, 3min
4520
2191
2185
6
1451
1448
1775
6140

TEC on, 25min (high temperature warning on)
5890
1513
2189
13
44
985
175
6115

Tested voltage against GND, all numbers are in mV, DC mode. Sequence are pin number defined in official spec sheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/OP295_495.pdf

[Bill W]

Ok I'd conclude that:

The 'TEC connected' is in fact power to the device and driver.
(as pin 8 is not 6100 or so unless TEC connected)

Initially the device is working OK (for itself) if not what you would want it to be doing
(pins 2/3 and 5/6 very close, 1 and 7 not at limits)

Does run flat out eventually
(pins 2/3 and 5/6 no longer close, 1 and 7 hit rail)

Now need to find where pins 2, 3, 5 and 6 come from.

Bill

[Logan]

Thank you Bill and sorry for the late reply.
Where should I find them? There are too many components...

[Bill W]

No idea, you are going to have to look and probe. 
First check if they go to any of the connectors on the PCB (ie come from another PCB) or look to track back the traces.

I'd expect the inverting input on each op-amp to attach to the (joined) emitters of each pair of  the drive transistors very like the attached opamp drive booster.

The non-inverting ones are the interesting one to follow.

Bill

[Logan]

Now need to find where pins 2, 3, 5 and 6 come from.

Thank you for help.
Please look at the picture and tell me what to do next.

[Fraser]

Logan,

As no one has responded yet, I will comment.

Well done for tracing the interconnections in the H Bridge that drives the Peltier Element 

Now the bad news. Diagnosing a fault and tasking another person to do diagnostic tests remotely is very challenging and time consuming. I have had a lot of experience of doing this and sadly stopped taking on such tasks some time ago as a diagnostic that would take me less than 15 minutes with the patient on the bench was taking hours of my time via messages to someone else doing the work. This is likely why you had limited responses to your request for help with this camera. Without schematic diagrams, working on thermal imaging cameras can be very challenging. I address that issue with complex faults by reverse engineering the area of the camera that I believe contains the fault. This is a time consuming task but is sometimes justified in time saved by not stumbling around a PCB in the dark looking for faulty components.

You have begun the process of reverse engineering the Peltier element control circuit but, alas, there is more work to do. Once the interconnections of the various components have been established, a proper schematic diagram needs to be drawn to provide a simple and clear picture of the circuits operation. The Peltier driver H Bridge is the output drive section of the Peltier Element controller. There will be control signals or voltage levels coming from other components on the PCB and it is important to reverse engineer that area of the design as well as that may well be where the issue with your camera resides.

Repairing thermal cameras is not a simple task for anyone not experienced in electronics repair and PCB reverse engineering. It can take a long time to build up the knowledge required to do it efficiently. It is certainly not a technology on which to ‘cut your teeth’ as no schematics are available. By comparison, repairing a laptop PC is relatively simple as schematic diagrams have often found their way into the public domain.

I am sorry that I cannot move forward with you on this repair adventure but I just do not have the spare time at the moment.

Fraser