Inframetrics PM290E, refill of the coolant possible ? - Page 1
Forum section: electronics / general

author: DC1MC
author_rank: Super Contributor
timestamp: August 13, 2022, 10:05:19 am
content: Hello thermal imaging experts and especially Mr. Fraser,someone close from where I live offers a defective Inframetrics PM290E with a lot of accessories and a nice carrying case:https://www.ebay-kleinanzeigen.de/s-anzeige/thermokamera-inframetrics-pm290e-defekt-mit-viel-zubehoer/2163195916-168-7986Assuming that due to the high moral integrity nobody will snag it immediately until I say I'm not interested anymore, cold you kindly have a look and tell me if it's worth the asking price, or how much should I haggle down to make it worth.But assuming that the non working condition is due to the coolant depletion in the Sirling cooler, is there a way for the layperson to refill it, or when is gone, is gone ?Thanks and cheers,DC1MC

author: Fraser
author_rank: Super Contributor
timestamp: August 13, 2022, 10:56:35 am
content: Hi,I paid £400 for my unit and it was £400 wastedThe Stirling Cooler in these units is a very common failure in these particular units. Either it suffers leakage of the Helium gas or the mechanics of the cooler fail.I have looked into the process of refilling the cooler with the required Ultra High Purity (UHP) lab grade Helium and even bought the required gauges etc for the task. After much research I realised it was going to be expensive , unlikely to actually work and was more effort than the camera was worth.Note that you cannot use just any old Helium in a Stirling cooler that has a cold finger operating at -196 degrees Celsius. No contaminants are permitted as such would cause the coolers pistons to lock up. Balloon Helium is very impure and of no use in these miniature Stirling Coolers. The air and water content will cause internal icing and lock-up the pistons.Sadly these old Inframetrics PM series cameras appear to be at the end of their operational lives as they are just not worth re-filling with Helium. People who know far more about re-filling such coolers tell me that a simple re-fill rarely works, even when carried out using the correct equipment. FLIR quoted something like £9K to rebuild the cooler in my PM280 and they no longer offer that service anyway.So what is that camera worth ? Well in practical terms....not a lot ! The lens is the only useful part and that is coated for MWIR and not a very hobbyist friendly design. Part of the lens resides inside the camera whilst the front section is the removeable part. The removeable lens on its own is useful only for harvesting the MWIR lens element which is often ZnSe and not Germanium on these units. I own two PM280 units and both are 'for display only' as they have failed coolers. I may harvest the lenses for experimentation with my other MWIR cameras.If you are hoping for an easy repair, this is not it. I suggest you keep looking for a more reliable MWIR camera, such as those that FLIR made. Working models are not cheap though.Best WishesFraser

author: DC1MC
author_rank: Super Contributor
timestamp: August 13, 2022, 11:09:28 am
content: So if I wunderstand correctly, neither the camera nor the accessories are worth putting an offer ?Cheers,DC1MC

author: Fraser
author_rank: Super Contributor
timestamp: August 13, 2022, 11:53:44 am
content: The accessories would really only be of use if you already had a working Inframetrics PM series MWIR camera. The lenses and 3.5um flame filter are really the only items of value in the kit. And the lenses are actually only half a lens as the rear element is inside the camera. The whole kit is pretty much a display piece only unless you need MWIR lens elements or parts to repair another PM series camera that still has a working cooler (a rare beast indeed!)Fraser

author: Spirit532
author_rank: Frequent Contributor
timestamp: August 20, 2022, 06:48:44 pm
content: It's usually fairly easy and quite inexpensive to refill cryocoolers, but it requires a significant amount of equipment(a few thousand dollars' worth if bought used).If anyone has dead units, I'm open to trying, as the system I built is capable of this, but I can't offer any guarantees whatsoever, only my vacuum, gas, and mechanical expertise.

author: TurboTom
author_rank: Super Contributor
timestamp: August 23, 2022, 03:54:27 pm
content: I actually stumbled across the offer on eBay Kleinanzeigen as mentioned by DC1MC before I even noticed this thread (I somehow neglected the thermal imaging section of the forum during the last years since my E4+++ performs satisfactorily and I didn't expect to need more sophisticated thermographing gear). Now that our turbine engine project is nearing completion, the need to measure higher temperatures at smaller FOVs arose and the offered camera cought my interest. So I sent the seller a nasty offerbefore I actually started searching the web for information on the PM290 or on inframetrics in general.Only then I came across this thread and I felt a little sorry for not having got in touch with DC1MC since he expressed his potential interest in this camera. But as it seems, after Fraser's consultation, he lost interest.Anyway, the seller got back to me and quote 20€ more than my offer and we agreed on a deal (paid 320€ shipping included).Today two(!) boxes arrived, one contining the camera with accessories in its hardcase, the other the two additional optics in their pouches (now there are 32°; 16° and 8° FOV). Batteries were not included but they would probably anyway have died of age. Seems like some Sony camcorder batteries may fit. But there was a car adapter included to power the camera and a 12V PSU. Whatsoever, I don't usually trust these way too many connectors, so I just hooked the thing up to my lab supply and turned it on.The Stirling cooler came to life with (IMO) way too much noise - sounds like a dry bearing - but what do I know about crankshaft-driven stirling coolers and the noise they are supposed to make? (linear ones are just humming as I learned when I built my air liquifier). Whatsoever, the camera greeted me with the message "maintenance recommended" and that it's cooling down the FPA. Considering the noise the cooler made and what I read here, I had little hope for any progress beyond that but I kept it running. To my surprise, after approx. 10 minutes, the cooler dropped in RPM despite 30° ambient temp, and the thing actually started to work!I played aaround with it a little and tested the three optics, and I've got to say, if it keeps working for a few years to come, this was very well spent money. It seems the camera has got four temperature measurement ranges so it will very well cover the required higher temperatures. The 8° FOV optics is also mighty impressive and will serve me well when thermographing our engine from the "business end"... I'm surprised that the vibration caused by the cooler doesn't seem to affect the picture quality.What's rather disappointing is the "toy like" view finder, but there is a small TFT screen included in the package that can be installed instead -- didn't try that yet. Next thing to arrange is a proper power supply, maybe to source some batteries and to find a way to easily transfer the stored images form the PCMCIA card to a PC... But apparently no "real" problems. I guess I got lucky!

author: DC1MC
author_rank: Super Contributor
timestamp: August 23, 2022, 09:55:50 pm
content: Hi Tom, no worries, I didn't actually have any use for it except thermographing my catand measuring the heat loss around the house windows and walls. At least it seems you've actually got a "real" use for it. So instead of traditional TEA biscuit I offer you a latest joke regarding some thermal things:"- Hey do you know what was used in Germany before the time when coal and candled usage become widespread ?- No... ?- Natural gas and electricity !!!"Cheers,DC1MC

author: TurboTom
author_rank: Super Contributor
timestamp: August 23, 2022, 10:37:26 pm
content: ... hopefully, this stays a joke and doesn't become bitter reality. Actually, viewed from that perspective, most of the stuff we're doing right now may be a moot effort, expecially my and my team's turbine project... But hoping that politicians may return to common sense again (did they ever??), there will be a time after the "candle and coal" period-- and hopefully this won't be the "new stoenage"!

author: Fraser
author_rank: Super Contributor
timestamp: August 24, 2022, 10:51:25 am
content: TurboTom,Excellent news. You did well 👍Rotary Stirling coolers are noisy when in the initial cooling down period before they reach operating temperature at the cold finger. The temperature maintenance mode is a lot quieter but you would still hear it from the other side of a room. If I tell you that the PM280 I have that has a mechanical failure in the cooler is so loud that I have to wrap a towel around it to quieten the noise, you will know that your cooler is likely not in such a state ! I cannot stand being in the same room as that damaged cooler…. Imagine a tin can full of ball bearings being shaken ! The amazing thing about that camera is that if I cool it to 5C in a fridge and run it, it gets to operating temperature and actually produces an image ! It is clearly low on Helium or the mechanical fault has lowered efficiency. Either way, the cooler is scrap.The “Maintenance Recommended” banner is based on cooler run-time hours and IIRC is triggered at 2000 hours. It does not mean the camera is faulty, just that the cooler has reached the end of its expected operational life before a service is due. Coolers of this era were like Projector Arc lamps.. they had a predicted life of up to 2000 hours. Some did not last that long, whilst others lasted far longer. New developments in cooler design over the years has significantly increased the expected operational life of the cooler with NASA predicting 10K hours to 100K hours depending upon model and some luck ! For space vehicle use, that specification is far more important than Earth based coolers.Regarding your cooler, a 10 minute cool down period is actually very good considering the age of the camera and hours run. Anything between 5 and 10 minutes is good. At 15 minutes the cooler likely needs a refill of Helium but will possibly keep working fine fir a good while. At 30 minutes cool down, the cooler is pretty much at ‘end of life’ and will likely not reach idle temperature maintenance mode in warm environments. With an ambient of 30C and 10 minute cool down, your cooler is fine for a good while yetThe batteries are absolutely standard 1990’s era camcorder battery packs that were just relabelled as Inframetrics. I forget whether they are the Sony NP series (NP55, NP75) as used by the Sony TR55, TR45, TR705 etc or they may be the similar looking, but different contact configuration, JVC batteries. The good news is that universal replacement batteries are available that cover both contact configurationshttps://www.amazon.com/Kastar-Universal-Battery-Panasonic-HHR-V20A/dp/B07915KPXGGet a battery with decent capacity as the cooler is power hungry and draws quite a lot of current at initial start. Really cheap quality batteries may not cope with that initial current demand.You got very lucky, clearly the seller thought it was faulty either due to the warning banner or inexperience with using this type of thermal camera. These are not as quick to use as an uncooled Microbolometer camera and some people may think that is a fault.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: August 24, 2022, 11:10:57 am
content: https://www.osibatteries.com/taga-pm280-thermal-imaging-camera-battery-3600mah-nimh

author: TurboTom
author_rank: Super Contributor
timestamp: August 24, 2022, 10:50:10 pm
content: Thanks Fraser for the hints and the "Thumbs up". Indeed, I already placed an order on two of those "universal" camcorder batteries with 4 Ah of capacity. Each should suffice for ~ 2h of operation (cooldown time included).I'm surprised that the camera electronics consumes quite some power -- in standby mode (cryocooler running), consumption is about 35% lower than in "all up" mode. So it makes definitely sense to wait for the cooldown to complete in standby mode and only after that switching over to full operational mode.I found some more quirks with the accessories like a broken conductor in an AC power adapter cable and some intermittent contact problems in a battery sandwich adapter that provides a mechanical interface to the flat screen display (looks very much homebrewn...) -- all fixable without a lot of effort.An then there's the broken rubber hand strap on the camera body that I've got to replace with some DIY solution -- not that I want to carry around the camera that much -- the strap is just super-convenient for lifting / inserting the TIC from / into its hardcase.Yet, there's one thing that really worries me: There's some interference in the thermal image, noticeable as irregulary moving horizontal "lines". These become more pronounced at lower thermal span (and high-contrast pallets) which makes me believe that they are the result of an electrical interference into the first gain stages after the FPA. It may be the result of power-supply induced noise, so I'll wait for the batteries to drop in for further testing. It may also be some faulty electrolytics. I hope it's not the result of a mechanical coupling of the cryocooler (vibration) to the FPA assembly.So as expected, there's still some work to be done on an almost 25 years old thermal imager, but I guess that's part of the fun!Cheers,Thomas

author: Fraser
author_rank: Super Contributor
timestamp: August 25, 2022, 09:24:40 am
content: TurboTom,In case you have not seen my teardown of one of the Inframetrics PM series cameras.https://www.eevblog.com/forum/thermal-imaging/inframetrics-flir-pm280-cooled-thermal-camera-teardown-for-repair/As you will see from that thread, I thought I had repaired one PM280 using the power board out of the other camera that I had. Sadly the cooler is right on the edge of not achieving the required operating temperature so takes a long time to cook down and cannot cope with a warm working environment. It needs a refill of Helium and woukd likely work fine after that. I therefore consider it to be non-working until refilled.Fraser