FLIR A20-M camera - the latest patient on my operating table - Fraser - Page 1
Forum section: electronics / general

author: Fraser
author_rank: Super Contributor
timestamp: September 16, 2022, 11:57:20 pm
content: Today I took delivery of a very nice FLIR thermal camera that was designed for both Industrial and R&D applications.The camera came to me as a "spares or repair" project so I was expecting it to not work when tested. I was actually pleasantly surprised by how much of it was working when I connected it to my laptop using Firewire and accessed the built-in web server. The web server permits camera configuration and provides camera specific data. I then used FLIR Researcher Version 2.8 to obtain an image from the camera. This is where a fault revealed itself. The produced image looked very odd indeed and something was clearly wrong with the FFC system. I tested the composite video output and found no video present. This was a previously declared fault so no surprise. I already had a good idea why no video was present, but more on that later.So going back to the strange imagery that the camera was producing when sending its data to FLIR Researcher...... there was a decent enough initial image, but it was when the FFC event occurred that the weird stuff happened. Whatever was in the field of view disappeared and did not return after the FFC event ! If the camera was moved, the scene reappeared with a ghost adjacent to it. I was using a hot cup of water as a test target so the effect was obvious. Those who repair thermal cameras will know exactly what is happening in this case. The FFC event is occurring and the FFC flag solenoid is operating, but the flag is not sitting in front of the microbolometer. The camera takes the thermal scene as its flat field reference.... hence why it disappears from view. If the camera is moved, the crazy out of wack flat field offsets appear as ghost images in the scene. Once another FFC event occurs, the ghost images disappear, but so does the scene, as once again the scene is taken as the flat field reference. This is classic FFC flag failure territory but I did not know the actual cause yet. I removed the lens to check the FFC flag presence and operation. I found the lollipop shaped FFC flag "swinging in the wind". It was clearly no longer rigidly attached to the FFC solenoid. Such a failure is thankfully a lot simpler to diagnose and repair than something involving the FFC solenoid driver or the solenoid itself. Phew, an easy repair was on the cards. Unfortunately, I also knew that I would have to completely dismantle the camera in order to gain access to the ffC flag and its mount on the solenoidNot a big deal though as I still needed to investigate the failure of the composite video output and that would involve removal of the PCB stack anyway.I carried out a complete teardown of the A20 in order to expose the problem with the FFC flag mount. I discovered that the one small screw that secures the FFC flag to the FFC solenoid was very loose and had allowed the FFC flag to uncouple from a locating pin that kept it in the correct position. I found no evidence of any thread locking fluid on that screw. The remedy was to apply thread-lock to the small screws threads, reassemble the FFC flag onto the solenoid and then apply a small spot of laquer to the screw head for good measure. It will not be shaking loose again any time soon. this failure surprised me as the camera has very low hours on it and so a very low FFC event count. The internal web server provides the cameras operation statistics....Total Runtime: 9 days : 20 hours : 20minutes and 42 seconds.Cold Starts: 180FFC Shutter Operations: 3323This camera has seen very little use in its life ! I can only assume that the FFC flag securing screw was not correctly tightened at the time of manufacture or thread lock was forgotten (other screws have thread lock applied).The cameras front section was reassembled and the investigation moved onto the absence of video at the composite video output BNC socket. In these cameras the composite video output comes from an ADV7173 video encoder IC that feeds the signal to the BNC socket via nothing more than a small filter comprising a series inductor and capacitor to ground. There is also a 75 Ohm resistor from the ADV7173 output pin to ground. The signal is DC coupled and this is an important point to note. Any excessive voltage applied to the video output socket of the camera is passed straight to the ADV7173 DAC-A output pin. If the voltage and current are high enough, the ADV7173 suffers damage to its DAC-A outputThis is not as uncommon an event as you might think !Upon visual inspection I immediately recognised the sad evidence of an excessive voltage and current having been applied to the video output BNC connector. .... there was a neat hole blown in the top of the 75 Ohm 0603 SMD resistor. Now this resistor sits across the DAC-A output and ground so whatever killed the resistor also got to the ADV7173 and caused damage there as well. The resistor would have needed a decent voltage to blow a hole in it so this poor A20 camera certainly suffered an unpleasant event on its video output. What that event was, we will never know, but it was not simple ESD, that is for sure. The only solution to this damage is to fit a new ADV7173 and 75 Ohm output resistor. The ADV7173 can still be purchased, but it is not inexpensive. Prices range from £14 to over £40 ! I was about to order some from Mouser at around £14 each but then found some old stock in the UK at Silicon-Ark for £4 eachOnce they arrive, I will fit the new parts, but in the mean time I could reassemble the camera for testing of the FFC flag function.Once reassembled I used Researcher to display the image of a hot coffee cup and was pleased to see that the camera now performed normally with no weird FFC ghosts in the system !I will attach the initial images captured when the FFC system was faulty and an image of the cup after the repair.For those unaware of the FLIR A20 and A40 series of cameras, these are very versatile units that were intended to provide good quality thermography for use in Industry, monitoring equipment, or for use in an R&D lab. The A series provide not only fully Radiometric thermal imaging, but also various analogue and digital I/O functions. The camera can monitor an external temperature LM35 sensor whilst also providing various alarm outputs if the thermal scene suffers a temperature excursion. The cameras can effectively be a preventative maintenance and failure alerting system in Industrial environs. In the R&D lab the cameras may be mounted on a table stand and used with FLIR Researcher software to carry out serious thermography on a target object or scene. Coupled to the PC and Researcher software they become powerful tools for those needing accurate thermal data.OK, enough of my waffle, time to go to the pictures.......EnjoyFraser

author: Fraser
author_rank: Super Contributor
timestamp: September 16, 2022, 11:59:55 pm
content: The images captured before the FFC fault was corrected and after the repair. There was ever only one coffee cup in the thermal scene ! I moved the camera to reveal the ghost image that was caused by the fault.

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:03:17 am
content: The teardown and repairs begin....The first two pictures show the FFC flag that swings freely within the lens mount due to not being correctly secured to its solenoid.

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:06:10 am
content: Continued.....

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:09:56 am
content: Continued......

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:12:25 am
content: Continued.....

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:14:39 am
content: Continued......(Rear panel PCB)

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:20:14 am
content: Continued.......

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:24:13 am
content: The damaged composite video output components......75 Ohm resistor with a hole blown in it and the ADV7173 that has a blown DAC A output.

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 12:29:53 am
content: Reassembly

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 02:04:54 pm
content: I have done some tests on 0603 size 0.1W 75 Ohm resistors. I tested voltages between 5V and 12V to see the destructive effect on the resistor. 5V cooks the resistor, 12V destroys it !I believe this camera suffered the application of 12V to its video output BNC connectorFraser

author: Bill W
author_rank: Super Contributor
timestamp: September 17, 2022, 02:23:18 pm
content: ... which is why on Argus cameras you'll find a fuse and a 5V zener diode attached to the video output.'It was the only socket so it must be power in.......... 'Bill

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 02:30:52 pm
content: I neglected to mention that this A20 camera came as a complete kit with the Firewire PCMCIA interface for a laptop and all the software supplied with the A20-M Researcher kit. This includes FLIR Researcher 2.8.I have previously mentioned in posts about buying 'Box' cameras the importance of obtaining the correct software and drivers to control them. Some are basically an expensive paperweight without their host interface hardware and software. The FLIR A20 and A40 are a little different however. They both contain a web server that may be used to configure the camera and even see the thermal image via the built in web viewer. Then there is the built in keyboard that can control the camera locally. The various menus come up on the composite video output. So these cameras may be controlled by FLIR Researcher, the Web interface over Firewire/Serial and the Local keyboard/menu system. These different ways to configure the camera make it a very versatile product.It is no wonder that a humble 160 x 120 pixel 30fps A20 "box" camera still commands significant sums of money on the used market (if working !) I only got my A20 at an affordable price after some hard bargaining and its "spares or repair" status.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: September 17, 2022, 02:52:52 pm
content: Bill,An excellent precaution to cope with careless end usersI have considered how someone might accidentally connect 12V to the BNC socket. These cameras are sometimes installed in tight confines with no visual access to the rear panel. Plugs are sometimes installed by feel. Sadly the shape and proximity of the 75 Ohm BNC connector could lead to it being mistaken for the power socket when using just feel rather than sight. The 75 Ohm BNC does not help matters by having a partially uninsulated centre pin that could feel like the centre pin of a power socket ! If a the power supply is switched on when the plug is placed in the BNC socket, it is feasible that power could be applied to the video output, even if only briefly.When looking at the ADV7173 datasheet I was surprised to see the standard use recommendation using a DC path to the video output socket and absolutely no protection on that vulnerable IC output pin ! I dislike unbuffered or unprotected I/O ports as users can really do weird stuff to those ports sometimes !I was indeed fortunate to find that the ADV7173 is still available, but at a cost. I was even more fortunate to find some NOS non ROHS stock in the UK at an excellent price. Sadly many specialist IC's used in video equipment have become obsolete and chip brokers gouge you for their rare stock. I no longer trust buying such rare IC's from China as they can still be expensive, and the sellers often have negative feedback claiming fake or non-working IC's. The Chinese sellers of the ADV7173 wanted between £20 (inc P&P) and £40 for their claimed genuine part. The seller of the £20 IC had some interesting feedback so was best avoided. I bought 4 of the ADV7173 IC from Silicon Ark at £4 each as it will be good to have a spares holding in case of future need.As a side note, the FLIR PM570 camera used a clever Brooktree BT858 video encoder. Brooktree were bought by another company and the IC was discontinued soon after. That IC is now unobtainium but thankfully reliable. FLIR chose to create their own video encoder by using an FPGA and this was used in the later PM5xx/6xx series cameras.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2022, 01:58:45 pm
content: Silicon Ark came through for me on the 'new old stock' ADV7173 IC's ..... excellent serviceNow I just need some spare time to change out the damaged IC and resistor on the A20.

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2022, 06:11:20 pm
content: I couldn’t wait so made time to do the repair. New 75Ohm resistor and ADV7173 fitted, camera reassembled and ………She is working perfectly and producing a perfect composite video signalI love these types of faults - provided the required replacement parts are still available, such faults are easy and quick to repairWell that is all for this cameras repair.

author: Jmenture425
author_rank: Contributor
timestamp: September 20, 2022, 08:28:42 pm
content: Great work, Fraser!I have an A40M that is my absolute baby/favorite "child" of my thermal camera collection. I had a rep from flir demo the new A-series R&D cameras that were running up to $40-60k and he asked to take pictures of the image my A40M was getting because it was handedly blowing them out of the water. The excuse he gave me was that the move towards smaller sensors makes it harder to pick-up as much photonic energy, but that didn't pass the smell test..Maybe higher %s of silicon vs. germanium..quality control ain't so easy when you decide to focus on "cost savings" in mainland ChinaPicture below is seeing through encapsulated silicon..total size is ~20mm edge to edge

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2022, 10:50:49 pm
content: I like my FLIR A40-M camera as wellIt was nice to also get my hands on its little buddy… the A20-MI reviewed my A40 here…….https://www.eevblog.com/forum/thermal-imaging/fraser_s-latest-aquisition-the-flir-a40-m-an-impressive-beast-)/It takes the same supplementary lenses as the FLIR PM series. I already had some of those in my collectionFraser

author: Fraser
author_rank: Super Contributor
timestamp: September 20, 2022, 11:25:45 pm
content: Of course, then there is the “Big Daddy” to the A20 and A40 cameras……. The amazing high frame rate cooled SC4000 that I am so fortunate to own. You will have some idea of it’s very low noise imaging performance from your FSI Prism (mentioned in another thread).I now have a “happy family” of these FLIR Scientific Box cameras

author: Fraser
author_rank: Super Contributor
timestamp: September 28, 2022, 11:01:14 am
content: Just some pictures of the repair and composite video output feeding my CCTV test monitorThe new 75 Ohm 0603 size resistor is the black one amongst the blue coloured originals and is marked "B5X". The new AD7173KST has a "Z" Suffix but this just shows that it is the ROHS version.The last image shows the built-in menu that is accessed and navigated using the keys on the top of the cameras casing. All important functions and configuration options are available via these drop down menus.Fraser

author: cejoba
author_rank: Regular Contributor
timestamp: November 26, 2022, 02:38:51 pm
content: Hi.What's the difference between A20M and A20V?Also I found it says 120mK thermal sensitivity, which seems pretty bad...Is that not NETD? Or is it not calculated at f1.0?Thanks.

author: Fraser
author_rank: Super Contributor
timestamp: November 26, 2022, 03:49:29 pm
content: The data sheets tell you all you need to know.The A20V data sheet states “Imaging” and the A20M data sheet states “Industrial Automation”The A20M is a thermal imaging camera for comprehensive radiometric measurement thermography. Such a camera may be used in a preventative maintenance, static area measurement or in a mobile measurement role. The A20V does not offer a radiometric thermography measurement function as it is intended for observations (like CCTV) rather than measurement..https://www.aaatesters.com/pub/media/datasheets/flir_thermovision_a20v_specifications_spec_sheet.pdfhttps://www.aaatesters.com/pub/media/datasheets/flir_a20m_specifications_spec_sheet_ti37.pdfRegarding sensitivity, FLIR are honest in their sensitivity claims and often provided specifications that may not impress these days, but they were always conservative in my experience. This is the difference between Industrial and Consumer product literature… less marketing bulls**t (note I said “less” and not “nil”) I have always found my FLIR Industrial cameras to far outperform their stated specifications, including those relating to measurement accuracy.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: November 26, 2022, 04:57:51 pm
content: It should be noted that both the A20M and A20V are more than “just” a thermal imaging camera…they are a thermal imaging system that provides Industrial application inputs and outputs on their rear panels. They can monitor and be controlled with their hardware inputs, including monitoring of an external temperature sensor, and they can raise alarms or warnings if temperature thresholds are exceeded. The A20V alarm system is not as sophisticated as the A20M due to it being a non radiometric cameraIf you look at the input/output specifications of these cameras you will see capabilities not normally found on consumer or pro-sumer thermal cameras. These are very much aimed at Industry and science where such capabilities are valued greatly. A classic example is thermal imaging of an area within a factory, monitoring the temperature of equipment 24/7. If an excessive temperature of say a motor is noted, an alarm is raised and the matter may be addressed before the situation escalates…… equipment down time or even fire ! Area monitoring technology is to be found on production lines and other machinery spaces, such as those found on ships, oil rigs etc.The ability to monitor external inputs, including temperature sensors adds to the information that he camera can send back to the central monitoring location.Fraser

author: cejoba
author_rank: Regular Contributor
timestamp: November 27, 2022, 12:08:47 pm
content: Thank you a lot!

author: cejoba
author_rank: Regular Contributor
timestamp: November 29, 2022, 01:54:13 pm
content: After a closer look, I found the A20's UI, lens mount, and shutter look almost the same as Flir B2/E2/E25/E45...Maybe they are indeed using the same image block, just different form factor?