Solved - Strange behavior TAU core - Page 1
Forum section: electronics / general

author: cejoba
author_rank: Regular Contributor
timestamp: October 23, 2022, 12:48:14 pm
content: Hi friends.I recently got a Flir FC-T camera, which have TAU 324 inside. I noticed several abnormal things compare to another TAU I have:a. The screen will quickly flash white after each NUC.b. There'sslowly changingrandom noise all over the picture, regardless of the scene. It changes much slower than frame rate, and migrate softly when changing. I don't think it's too high gain because it doesn't show more contrast on flat scenes, compare to the other TAU. And it look like artificially added, does Flir even do this on TAUs?Both are not the case on my other TAU. I may have more clues after repair my broken TTL cable...Anyone have experienced such things? Welcome to discuss.

author: Fraser
author_rank: Super Contributor
timestamp: October 23, 2022, 01:27:28 pm
content: Am important question… was the camera new or is it decommissioned ? If it is the latter, I would consider the possibility that it was removed from service because of the Noise issue. The FC-T series do not have artificial noise injects to engrave them compared to a standard TAU. Possible causes of your symptoms are noise injection on the power supply cables to the TAU and a Buck converter on the TAU internal power supply. There are several such buck converters on the PCB and they are easily recognised by the inductor that forms part of each one. It could be an MLCC output capacitor failure. I have seen a similar issue on one of my Seek Reveal cameras and it was faulty power supply MLCC allowing noise to get to the microbolometer analogue to digital converter via power and bias voltages.I did a repair of a TAU core some time ago and documented it on this forum. I will see if I can find it.Regarding the white screen after each FFC event, that is something I have not seen before and I am uncertain whether the TAU GUI offers an option for such behaviour. Your CCTV camera was an analogue composite video output model so it is unlikely that the white screen was intend as story of host system image equalisation process. Sorry Incannot help more on that haviour.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: October 23, 2022, 01:32:20 pm
content: Here you go, my tear down that contains details of the TAU power supply board and expected voltages. From memory one voltage, I think it was the 12V rail can be 9V on some versions of the core.https://www.eevblog.com/forum/thermal-imaging/thermal-camera-teardown-the-flir-tau-320-by-fraser/25/Hope this helps

author: Fraser
author_rank: Super Contributor
timestamp: October 23, 2022, 01:38:59 pm
content: The relevant documents for power on a TAU….It would be worth checking each rail with an oscilloscope to see if there are any obvious noise issues.For information, I attached fine wires to each buck converter output to measure the voltages but sadly I did not record noise levels on each rail. As I thought, the boost converter on the Power PCB can be either 9V or 12V depending upon the version of the TAU.Fraser

author: cejoba
author_rank: Regular Contributor
timestamp: October 23, 2022, 04:08:05 pm
content: Thanks a lot Fraser. It's unusual to see someone keep handwriting notes nowadays, lovely.Quote from: Fraser on October 23, 2022, 01:27:28 pmIt's a used one.Quote from: Fraser on October 23, 2022, 01:27:28 pmThis is a reasonable guess! Unfortunately I do not have a scope.The noise is not that unbearable though, I'll try change the settings first. Thanks.

author: cejoba
author_rank: Regular Contributor
timestamp: October 26, 2022, 05:58:04 pm
content: Problem solved, it's just software configuration...However, my friend's BAE SCC500 with only 160x120 outperform my both TAU 320 and 640, which is unbelievable...

author: Fraser
author_rank: Super Contributor
timestamp: October 26, 2022, 06:23:30 pm
content: The BAE SCC500 was designed for military applications including personal weapon sights and heat seeking air to air missilesThe use of such capable cores in fire fighting was a secondary application authorised by the US Government for specific use cases.This is why I love some of the older technology thermal imaging cameras and cores …. They cost a small fortune and their performance was optimised, sometimes at great cost. The TAU and it’s like also see service in military applications but they are a cheaper design with more compromises. I have a number of SCC500 cores because I like the images that they produce.Fraser

author: cejoba
author_rank: Regular Contributor
timestamp: October 27, 2022, 12:34:58 pm
content: Thank you Fraser.I have two more questions...1. Can I update my TAU 2.4 to 2.7?2. My TAU 640 shows hot edges after power on for a while. It's not the lens, it maybe from the camera chassis(it's indeed the shape of the frame opening), and it do not go away with NUC. How can I fix this?