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

[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