Fluke TI32 Error Question and Calibration Reccomendation - Page 1
Forum section: electronics / general

author: jasoncpe
author_rank: Newbie
timestamp: February 05, 2022, 07:09:42 am
content: I recently purchased a new (but old stock) TI32. Applications are building science and MEP, for professional use. I bought it because I really liked the specs on this model- very good for our our application and I had the opportunity to purchase it far less than anything with matching specs currently.Upon powering it up everything seemed normal. I let it "warm up" for 10 mins and then tried it out for a couple hours today including checking ice water and almost boiling water and a few things in between. -Operation/ readings were all appropriate. I checked various building exterior building walls/ windows, loose exterior doors, rim joists, hot and cold pipes, areas of known thermal bridging, moisture etc. and still all was good. I checked all the menu settings, upon start up- everything where it should be. Pretty much everything on auto (including range and default emissivity.Then, all of the sudden it seems it is displaying temperatures that are way off. The lowest temp of something that should be ~70F shows up as ~180 degrees F and some readings are showing much higher- off by over hundred degrees F. Then I tried to take it outside (where it is about 30 degrees F currently, and the second I point the unit outside the temperature indicator drops to -22 degrees F and the screen turns black. I shut down and restarted a couple times, same thing.I'm assuming the unit is out of calibration...after all it probably sat in a box for at least 5 years. I don't know enough about deciephering Fluke serial numbers to tell what year it was manufactured- but I"m pretty sure between 2010 and 2015.However, it clear it is brand new and undamaged and the seller is reputable (and would take it back). It doesn't make sense to return it if it just needs a calibration as any unit is probably going to need a routine calibration every couple years if accurate data is expected.It's perplexing that for the first couple hours everything was reading as expected. If it was just out of calibration, wouldn't it likely have started up that way in the first place?Differences of adjacent readings and temperature variations are quickly detected, but magnitudes are way off. Hot water that is ~130F is close to 500F, then cold water that is ~45F shows up around 30F. Then I measure my arm and it shows ~300F.Assuming it is a calibration issue (and hopefully not something greater) - I know the unit will be out of warranty (even though brand new) as Fluke discontinued this model some time ago. I'm thinking of using Fluke since I assume that is the best place to send the instrument but Fluke calibration/ service prices are reportedly crazy once out of warranty or discontinued. (I'll verify this firsthand).Questions: Is it agreed this is most likely a calibration issue- or other thoughts?Is there anywhere else experienced persons/ thermographers have had good experience for this service on Fluke equipment (and should be accredited labs)?Just venting: I'm a little frustrated as I didn't expect calibration costs to be as crazy as I'm seeing upon quick search. I guess I was dreaming when I figured ~$500. On the other hand, maybe it's just as well because if I had paid 11K for a new unit (the current TI32 replacement is a TI480 going for ~11K) I would be pretty ticked off to need to pay ~$1500 PY to calibrate, especially since usage is only about once every week or two.thanks for any input-J

author: Fraser
author_rank: Super Contributor
timestamp: February 05, 2022, 11:03:54 am
content: Sadly I disagree with your thoughts that this is ‘just’ a calibration issueLet me explain why…..Good quality thermal cameras do not suffer calibration drift of any significance and are normally subject to calibration checks rather than annual recalibration. This is to ensure that the camera is still working within specification and does not normally lead to the creation of new calibration tables. Regarding cost of ownership….. Calibration checks are easy to do if you have the correct Blackbody sources and do not take very long to do. In the UK such check would be around £200. Creating new calibration tables for a thermal camera is a very different matter. A full calibration run on a thermal camera requires multiple Blackbody sources, access to the factory calibration utilities plus a lot of time. The result of this additional work is a somewhat scary bill from whoever did the calibration. Thermal cameras only need a calibration check to confirm accuracy. If they fail this check, it is often due to an issue that is not a simple fix by doing a recalibration. Few ‘calibration houses’ have the capability to actually create new calibration tables on thermal cameras and will refer you to the manufacturer. This is due to the required proprietary calibration utilities that are hugely expensive or not available buy.What you are describing in your post is almost certainly a fault in the measurement side of the camera. If it is producing reasonable imagery yet the temperature measurements are way off, it is not the core thermal image creation system that is at fault.In a thermal camera the microbolometer and associated image processor provide a scene of Radiance levels that are measured in ADC Counts.. The Counts are converted to temperature units using a Radiance to Temperature Unit ‘curve’. To correctly locate the conversion curve with respect to the Radiance levels a multi point calibration is used. This calibration against a thermal source of known emissivity and temperature provides the ‘anchoring points’ for the conversion curve.So what can effect the correct measurements of a thermal camera ?1. The calibration data can become corrupted or lost. Such would necessitate the creation of a fresh calibration table. Such calibration data loss in a thermal camera is most unusual. The calibration data is normally stored in the same memory system as the Non Uniformity Correction table and Dead Pixel Map. I would expect to see clear evidence of a non uniform flat field and many dead pixels on a the display of a camera that suffers damage to its ‘calibration’ memory. I cannot remember ever seeing a thermal camera that stores its vital calibration, NUC and Dead pixel data in a battery supported memory IC. I know that this is not true in Test Equipment circles but thankfully Thermal Cameras do not do this as a general rule. Corruption of the Calibration table alone is also a very rare event, but memory IC’s can suffer memory cell degradation over time so theoretically it could occur. Your camera originally started and operated correctly though and this leads me to doubt that scenario.2. A thermal imaging camera monitors the temperature of the Flat Field Correction shutter/flag that is used to both provide a decent flat field for Fat Field correction, and a temperature reference against which the cameras measurement systems may calibrate themselves. The FFC shutter/flag will be of a known temperature thanks to an adjacent ambient temperature sensor. The camera will be able to check its optical measurement of the FFC shutter/flag temperature against its known true temperature and correct for any drift in the measurement system. Any error in the measurement of the FFC shutter/flag will be transferred to the measurements produced by the cameras measurement system.3. There are often other temperature sensors in a Radiometric thermal camera system, including one or two on the Microbolometer die that measure the die temperature. All such temperature sensors have their part to play in the thermal cameras measurement accuracy. If any fails to produce valid data for the measurement system, errors will likely be introduced to the system.I suspect that your camera has a fault rather than just a ‘simple’ drift in calibration. It operated correctly for a period of time and then something changed that caused the measurement side of the system to fail. As to exactly what is at the root of this measurement issue I cannot say for certain but if I had the camera in front of me I would carefully profile the behaviour of the measurement system using a Blackbody temperature reference. Through testing I would determine whether the measurements being produced had any form of pattern or underlying trend that could suggest a cause. Sadly the FLUKE cameras are a closed system and I know of no self test modes or access to a service menu that would normally provide essential information about what the internal temperature sensors are providing in terms of data to the cameras measurement system.I will think more about this and let you know if I come up with any suggestions for tests etc.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: February 05, 2022, 11:34:24 am
content: Just to make things clearer for those of us who work in Celsius and to assist me in visualising what is happening here, I have produced this list of measurements from you post.All temperatures in Degrees CelsiusTrue Camera. Differential-1. -7. -6+7. -1. -8+21. +82. +61+36. +148. +112+54. +260. +206What is clear from the above readings is that we are not looking at a calibration drift situation.The measurement error is increasing dramatically as the scene temperature increases and is displaying crazy levels of error by the time the scene is at 54CThe human arm is usually at around +36C so this is a good data point against which to assess the cameras measurement. A reading of 148C for the arm is hilarious !I will look at these data points and report of I have any thoughts on the cause.

author: Fraser
author_rank: Super Contributor
timestamp: February 05, 2022, 12:05:04 pm
content: Having looked at these magnitude of the measurement error in this camera, it is not a simple case of the Radiance to Temperature Unit translation curve becoming ‘unlocked’ from its multi point calibration. I even checked that the camera was not displaying temperature in Kelvin ! Nope.This cameras measurement system is very sick indeedFraser

author: Fraser
author_rank: Super Contributor
timestamp: February 05, 2022, 12:20:34 pm
content: Going back through my repair archives I have seen some truly crazy measurement errors produced by thermal cameras that lose the ambient temperature data due to either a fault in the temperature sensor or the connections to it. In the absence of valid ambient temperature data being provided, the measurement systems of some thermal cameras basically go berserk and it is hard to extrapolate what is going on from the wildly inaccurate temperature measurements being produced.I would be looking closely at the ambient temperature monitoring circuit in your camera. If the ambient temperature sensor is connected to the main board via flying leads or inter-PCB connectors, I would be looking for corrosion on the connector pins. Some ambient temperature sensors are nothing more complicated than a silicon diode or thermistor and due to the low currents flowing in the circuit (to reduce self heating) can suffer issues if corrosion/oxidisation is present in the sensors connections to the main board.Your camera may have initially worked OK but the connections to the ambient temperature sensor may be tenuous.Fraser

author: Bill W
author_rank: Super Contributor
timestamp: February 05, 2022, 02:21:43 pm
content: How about emissivity has been set way to low, say to 0.1 or 0.2, as an idea ?OP should certainly check thatBill

author: Fraser
author_rank: Super Contributor
timestamp: February 05, 2022, 03:43:36 pm
content: Bill W,Excellent suggestionSuch a low emissivity setting would certainly mess things up. I should have thought of that. Too quickly into hardware diagnostics mind setFraser

author: jasoncpe
author_rank: Newbie
timestamp: February 05, 2022, 05:33:36 pm
content: Fraser and Bill thanks for the thoughtful replies. Fraser had me convinced then Bill got me checking things out and trying to retrace the steps.Now I'm thinking something is going on with the camera not retaining emissivity setting.Yesterday I had started it at 0.95 as I was sweeping various interior building surfaces (drywall/ wood/ general non-shiny stuff). I checked it at it was at .95. This morning when it powered on it was at 0.05. I recall that when I was working with it yesterday I set it down for about 10 minutes and when I picked it up it was in "sleep" mode (but not off). and I'm thinking (don't remember exactly) that it might have been just before I noticed things were weird. I didn't save the images so I can't confirm what setting was in place at the times I was noticing things were off= but I know I didn't change it.I was tired and I'm second guessing if I rechecked the emissivity. I pretty much had it in my head that the calibration was off because I knew I had set it and all was good for at least an hour before.So just now I powered it up, reset the emissivity to 0.95 and readings seem normal. I set it down for a few minutes now and it seems to have gone to sleep again...but when I picked it back up it was at 0.94. Which seems weird because just 5 mins ago I had set it at 0.95. Small difference, but why would it change at all?Is there some kind of glitch that could cause emissivity settings to drift? I'm going to try a few more times today and see if it continues. I'm far from an electronics expert but wonder if it is a software issue?

author: Fraser
author_rank: Super Contributor
timestamp: February 05, 2022, 07:54:10 pm
content: I have learnt my lesson here ….. I should not second guess causes of issues without having the unit on the test bench in front of me

author: jasoncpe
author_rank: Newbie
timestamp: February 06, 2022, 12:21:34 am
content: It's changing after it goes to sleep! Then if I reset it stays...until it goes to sleep.

author: Fraser
author_rank: Super Contributor
timestamp: February 06, 2022, 01:05:53 am
content: OK, I will suggest some tests…….1. Set up the camera fully - time, date, emissivity…. Everything.2. Switch it off using power button and switch back on - has any setting changed ?3. If nothing changed, switch off the camera again and then remove the battery for a few minutes. Refit battery. Start camera. Has any setting changed .4. If nothing changed leave the camera to go to sleep then wake it from sleep. Did anything change, if so please detail original setting and what it changed to.5. If a change occurred repeat the test that produced the change several times with the camera correctly configured then allowed to change the setting(s). Do the changed settings always go to the same new value ? Some cameras go to a default set of ‘factory defaults’ if they do not like the current configuration checksums e.g. the OS detects a data corruption so loads a safe set of defaults.Give us as much detail as you can on what changes, and from what value to what new value, and I may be able to determine whether this is a RTC battery issue or something more sinister.Fraser

author: jasoncpe
author_rank: Newbie
timestamp: February 07, 2022, 07:08:29 am
content: It may take me a couple days to get to this, but thanks for this suggestion. I noticed yesterday that a couple times it shut off while I was holding it and I"d have to power it back on. Now I'm thinking it may be that one battery is not holding a charge properly. It is Li-ion. I'm going to give both batteries a good charge and try what you suggested...but it will be a few days before I can get back to it. Pls stand by and thank you.