Author Topic: Faxitron MX-20 x-ray system teardown  (Read 52743 times)

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Offline IanB

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Re: Faxitron MX-20 x-ray system teardown
« Reply #100 on: January 30, 2015, 06:57:02 pm »
About drying oil, my chemical experience tells me that this will be a rate based process, and that the process will be sped up by increasing the rate of mass transfer. For instance if you just leave the oil to sit under a vacuum, even with the encouragement of heating, the dissolved water will only be able to leave if it reaches the surface by diffusion. This will happen eventually, but it may take some time.

To speed up the process, stirring or agitation may help as it will expose new oil to the surface at a greater rate. If you bubbled dry gas through the oil the moisture would migrate into the dry gas bubbles (welding gas?) and be carried out and away with the escaping gas. The gas bubbles would also produce some mild agitation to promote mixing and bringing all the oil into contact with the bubbles. Obviously warming would also help to speed things up.

I have no actual experience of doing this with transformer oil, but theory indicates it would be a reasonable approach. Of course heating under vacuum may be quite satisfactory too. This is just an alternative to consider.

Note: For gas bubbling, efficiency is increased by having a large number of small bubbles (maximum surface area) rather than a few large ones. An aquarium bubbler might be a possibility. (Of course, gas bubbling might dissolve gas in the oil, which might also be undesirable. If the oil needs to be de-gassed, then vacuum, heating, and perhaps agitation will be the only solution.)
« Last Edit: January 30, 2015, 07:58:06 pm by IanB »
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #101 on: January 30, 2015, 07:49:52 pm »
@IanB,

Many Thanks for the comment on oil drying.

Aurora
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Offline SeanB

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Re: Faxitron MX-20 x-ray system teardown
« Reply #102 on: January 31, 2015, 10:40:18 am »
I bought a lot of cheap gas mantles at the local China mall, and they are a little above background level. They were sub $1 per dozen, so you might want to go to the nearest Poundland and get a few packs of the cheapest mantles to try. About the only time you really want to get a counterfeit product.
 

Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #103 on: January 31, 2015, 10:54:40 am »
Thanks for the tip.
I have been doing some Googling on Thorium and its derivatives.
The down side to gas mantles is that the Thorium used in them has a half life of less than 2 years. An occasion when new old stock may prove unfit for purpose.
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #104 on: January 31, 2015, 06:30:16 pm »
Well the Thermo EPD Mk2 arrived today.

The quality is excellent, as you would expect with such a safety device. The unit is totally unlocked so all facilities and menus are present. The unit is pretty sophisticated in that it has two dose types, multiple alarms and user settable alarm thresholds. This combine with its ability to store accumulated H10 and H07 dose, total dose and dose rate. A comprehensive dosimeter that offers even more when connected to a PC for data downloading. I will connect to my PC once I find my trusty RS232 IRDA dongle that the EasyEPD software requires.

I attach the first pictures of my unit. Sadly there will be no tear down as these units are known to contain a lot of shielding that is not easily re-assembled without affecting performance of the unit. I have attached a couple of pictures from an e*ay sale of the similar EPD1 PCB.
« Last Edit: January 31, 2015, 06:44:02 pm by Aurora »
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #105 on: February 01, 2015, 12:22:21 am »
Well the easyEDP software test went badly.

I have the correct Actisys ACT-IR220L+ IRDA dongle but it turns out the software I have is for the earlier EPD1 dosimeter. The software just ignores the EDP2  :(

I have written to Thermo Scientific to ask whether a trial version of the easyEDP2 software is still available. I understand that such did once exist.

My unit will work fine in stand alone mode as I can configure it and zero the dose count etc, but I cannot produce dose trend graphs etc. No great shakes but a pity all the same.

If thinking of buying a EPD2 or any modern dosimeter, ensure that it is not locked down in any way as it would appear expensive software is needed for configuration on these things to remove such restrictions.

Aurora
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #106 on: March 03, 2015, 04:25:32 pm »
Uh Oh, I have been buying potentially dangerous stuff again  :palm:

I have just taken delivery of a Philips/Gendex Oralix AC 65S Dental X-Ray System, complete  >:D

I could not resist the unit because it comes with everything except the often missing Collimator tube. Not fussed about that as it is easy to build and of little use in my application anyway (it tightly contains the beam to minimise the X-Ray dose to which the patient is exposed. It is not my intention to ever be in the beam when the unit is operating !

This system design has been around a good many years and is a pretty good basis for experimentation. It is compact, relatively light and simple to operate. Maximum exposure level is safety limited to 3.5 Seconds and normal exposures are up to 2.5 seconds. The head runs at a fixed 65kVp with 7.5mA current through the tube. the output is filtered with aluminium to remove the soft X-Ray content. You can see the filter at the centre of the output port in the attached picture.

These units were originally named the Dens-O-Mat and made by Philips. They went on to be manufactured by the venerable Gendex of Milan, Italy. The controller bears the name Dens-O-Mat yet the head is named the Oralix  :-// Mine is the 65kVp version as already stated and so the ID is '65S'. Such systems still command relatively high prices on the secondary market. You are lucky to get a working one complete will all parts, in the UK, for less than £1000 ($1500). Repairing a faulty Oralix head is not something I would recommend. Messy and difficult. Another bit of good fortune is the fact that the user and service manuals are available for free download on the internet. Good for if/when things go wrong  :)

I won this one for a more budget friendly £237 via an e*ay auction  :) it was delivered by the seller in a Mecedes so no risk of transit damage. This is something to be considered when buying dental X-Ray heads...... they tend to be fragile and do not travel well if dropped !

The unit that I have purchased is the free standing version so it has a trolley rig that supports the articulated arm and associated X-Ray generator head. Its all counter balanced by strong springs in the arms so the head is light as a feather to move around. I will attach a picture of the full system that I found on the web. I have yet to put my trolley together. It all looks in very good condition and I believe the Oralix head is newer than the rest of the rig. The build date is 2005 yet the box shipping label states 2011. (Old stock ?) Either way, the head is in great condition with no damage.

It goes without saying that a dental X-ray head comes with some serious health and safety issues as there is no beam containment and and no safety interlocks to shut the beam off if a person walks into it by accident. As such, this is not a toy. It has to be used in accordance with Dental X-Ray best practice and this is easily found on the web. The room in which it is deployed must be a controlled space to prevent the innocent wandering in and being irradiated. The beam must not illuminate areas that contain life, including pets. In some cases the room is lead lined to meet this criteria. The user of such equipment must be educated in safe usage of such open site equipment (I am formally trained for using such equipment). The use of such equipment for experimentation can lead to accidental illumination of the user. For this reason I highly recommend that the user is either X-Ray badge monitored or equipped with a quality X-Ray dosimeter that works at <45KeV (Kev is less than kVp due to losses). OK that is the warning bit, I have to say it as these units are potentially bad for your health if misused and I wouldn't wish that upon you dear reader.

I will be taking the covers off of the units but the head is pretty uninteresting as it is basically a lead shielded cylinder with only the connections visible. I shall not be dismantling this perfectly good X-Ray generator any time soon. The control panel is not just a single timer. It contains the 'warm-up' phase pulse generator and a multi setting pre-set timer that can have its timings globally adjusted to suit the patient age and film speed. There is only the controller and the head in this system. No external power supply unit or other messy parts needed.

I intend to use this X-Ray generator in experiments illuminating various X-Ray intensifier screens whilst observing the performance via CCTV. I will also be experimenting with image capture using digital cameras and specialist analogue cameras designed for the task (Ex EOD equipment).

I may also be doing some tests on Geiger Muller tubes and meters but that is a low priority for me.

An open site X-Ray generator can be very useful if you have the correct environs and a suitable mobile detector plate. I lack the latter at the moment so will be developing my own using intensifier and electronic camera techniques.

Pictures of unit (as received) attached.

Aurora
« Last Edit: March 03, 2015, 04:54:35 pm by Aurora »
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Offline dexters_lab

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Re: Faxitron MX-20 x-ray system teardown
« Reply #107 on: March 03, 2015, 07:47:58 pm »
nice  :-+

i have looked at dental xray before, thankfully i always close the browser tab and say "no no no!"
« Last Edit: March 03, 2015, 09:50:44 pm by dexters_lab »
 

Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #108 on: March 03, 2015, 08:11:08 pm »
They are normally too expensive and incomplete for me to even consider. I am under no illusions that this is my most risky X-Ray source so it will be used with the greatest of care. As I have stated, I do not recommend open site X-Ray for casual use. The safer cabinet type X-Ray inspection systems are far better, as they are normally intrinsically safe. It should also be noted that this Dental X-Ray generator has a 0.7mm spot size, and so is not that good for high resolution imaging. i.e. it is not equipped with a microfocus tube.

Aurora
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Offline dexters_lab

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Re: Faxitron MX-20 x-ray system teardown
« Reply #109 on: March 03, 2015, 10:18:11 pm »
Radiation test source

Further to my comments on a Dosimeter, it is also a good idea to have a radiation test source with which to check your dosimeter.

Some Dosimeters come with a test source but most do not. A used one is very unlikely to come with such. So where do you get one from ?

I have come across two easily obtainable radiation test sources

1) Fiesta Orange or Red crockery from Circa 1930 Uranium glaze  - Alpha emitter
2) The Americium 241 source installed in an ionisation smoke detector- Alpha emitter

The Fiesta crockery may be found on ebay for a few pounds per square inch, or maybe find some in a thrift / charity shops ? It is more common in the USA than UK.

The ionisation chamber of any ionisation type smoke detector contains a small gold coloured pellet of Americium 241 at the bottom of the chamber. You can extract the chamber and use it without the top shield as a test source. A word of warning, the bulk purchase of ionisation smoke detectors can attract the attention of your local authorities ! They are also a banned product in some countries due to their radioactive content.

The above freely available and safe radiation sources are legal to own and use but you must not ingest the source in any way as it is a harmful Alpha emitter, that once inside your body is very bad news.

Both are Alpha emitters but they also produce Gamma or Beta radiation as a bi-product. They work well when used with Geiger counters and other types of radiation dosimeters that can detect Alpha, Beta or Gamma radiation.

I understand that unused 'new old stock' gas mantles are also used as radiation test sources as they contain radioactive Thorium. I have not tested such however. The Thorium impregnated types are apparently now illegal in the USA.

Aurora

thorium enriched mantles are hard to find now, enriched welding rods also have thorium in them, both often carry a radioactive premium price on ebay.

TBH if you want a decent source, just get some uranium mineral, i picked up a nice piece from ebay which was shipped for £25 from the USA. I have seen 8000CPM on mine with it right up against my mightyohm counter which has a exposed tube.

americium is a good sample to have, it's alpha particles are of enough energy to generate detectable xrays

uranium glass is sold on ebay without the 'radioactive premium' price as antique glassware, it's not particularly active, about 3x background

proper sources seem to be really expensive here in the uk it seems

Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #110 on: March 17, 2015, 05:05:54 pm »
Whilst searching for something unrelated, I stumbled upon an interesting story about a radiation incident in Italy. It made fascinating reading and I thought readers of this thread might like to read it as well:

http://www.wired.co.uk/magazine/archive/2011/12/features/mystery-box/viewall

I have always considered isotopes something best avoided. After reading this story I suspect many will agree with me ! I know a couple of medical recycling companies and have already warned them about opening anything that may contain a radioactive isotope source. Nasty stuff if you you get an unexpected one in your auction lot ! The cost of correct disposal could bankrupt a small company.

Aurora
« Last Edit: March 17, 2015, 05:18:11 pm by Aurora »
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Offline TopLoser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #111 on: March 17, 2015, 05:21:37 pm »
Whilst searching for something unrelated, I stumbled upon an interesting story about a radiation incident in Italy. It made fascinating reading and I thought readers of this thread might like to read it as well:

http://www.wired.co.uk/magazine/archive/2011/12/features/mystery-box/viewall

I have always considered isotopes something best avoided. After reading this story I suspect many will agree with me ! I know a couple of medical recycling companies and have already warned them about opening anything that may contain a radioactive isotope source. Nasty stuff if you you get an unexpected one in your auction lot ! The cost of correct disposal could bankrupt a small company.

Aurora

This story always sends a chill down my back... it makes for incredible reading:
http://en.wikipedia.org/wiki/Goi%C3%A2nia_accident

 

Offline jaxbird

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Re: Faxitron MX-20 x-ray system teardown
« Reply #112 on: March 17, 2015, 05:41:26 pm »
Analog Discovery Projects: http://www.thestuffmade.com
Youtube random project videos: https://www.youtube.com/user/TheStuffMade
 

Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #113 on: March 17, 2015, 05:45:14 pm »
@Toploser

Indeed, I know that factual story well.

The part of it where child covers herself in the 'pretty blue glowing powder' shocked me to the core. Virtually certain death, as occurred. A really good example of what can happen when medical equipment containing dangerous Isotopes lose their management and are lost or stolen. The stuff of nightmares for scrap metal dealers receiving anonymous piles of scrap equipment or parts.

Makes my Faxitron a real pussycat by comparison but I still have the greatest of respect for its X-Ray output.

Aurora
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Online mikeselectricstuff

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Re: Faxitron MX-20 x-ray system teardown
« Reply #114 on: March 17, 2015, 06:50:22 pm »
I think it's a great shame that we've ended up having the same symbols for x-rays and isotopes, as the potential hazards are so different, especially when outside their normal working environment.
It wouldn't surprise me if it's not even required to put the poison symbol on isotope sources, which might be a little more recognisable.



 
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #115 on: March 17, 2015, 07:13:11 pm »
Mike,

There is a new sign designed for deployment inside equipment that contains hazardous isotopes. It is supposed to be a pictagram rather than a symbol. I have yet to see it in the real world but then I do not get involved with Isotope equipment now so no surprises there eh  :)

The new label is shown top left in the attached image.

I would have loved to be a fly on the wall at the meeting where that new sign was designed and agreed. My interpretation of the meaning is..... 'STUFF' is coming after you to turn you into bones....run rabbit run  ;D

Aurora

 
« Last Edit: March 17, 2015, 07:17:05 pm by Aurora »
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Online mikeselectricstuff

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Re: Faxitron MX-20 x-ray system teardown
« Reply #116 on: March 17, 2015, 08:37:02 pm »
I wonder how close an international symbol you could get for
"This thing will F***ing kill you and your family"
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #117 on: December 07, 2015, 11:56:59 pm »
As this thread does not have a set of internal pictures (rather than video) I thought I would add some.

I inspected the X-Ray generator of my spare Faxitron MX-20 and took the opportunity to take some photographs. This unit does not have the Digital Camera in the bottom as it is a 1999 film only unit. The cabinet and X-Ray Generator is the same as the later MX-20 Digital models.

I noted two inner cover screws were missing and and others were loose. I feared the unit had been tampered with but it was not the case. The missing and loose screws appear to be the result of a 'tech' fitting a new Microfocus X-Ray tube. The MX-20 was built in 1999 yet teh X-Ray tube is dated 2008. Obviously the tube has been replaced. It is a pity that the tech was less than professional when it came to reassembly. The unit works fine though.

Pictures follow:

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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #118 on: December 07, 2015, 11:59:28 pm »
More pictures
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Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #119 on: December 08, 2015, 12:01:21 am »
More pictures
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Offline kilohercas

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Re: Faxitron MX-20 x-ray system teardown
« Reply #120 on: January 30, 2017, 06:53:17 pm »


Here is my new toy
 

Online Fraser

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Re: Faxitron MX-20 x-ray system teardown
« Reply #121 on: January 31, 2017, 09:09:35 am »
Thanks for taking the time to document the internal parts of your unit.

Fraser
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Offline LukeW

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Re: Faxitron MX-20 x-ray system teardown
« Reply #122 on: February 10, 2017, 03:30:57 am »
So I guess the UK is relatively liberal in terms of ownership of X-ray sources without licensing and regulatory paperwork?
 

Online mikeselectricstuff

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Re: Faxitron MX-20 x-ray system teardown
« Reply #123 on: February 10, 2017, 08:58:41 am »
So I guess the UK is relatively liberal in terms of ownership of X-ray sources without licensing and regulatory paperwork?
AFAIK there is no regulation in the UK covering ownership or sale of equipment.
The legislation is somewhat unclear over usage,  however consensus seems to be that use in a non-business scenario is not subject to regulation, though I'm not entirely convinced.
It's one of those things that so few people do as a hobby that nobody had addressed it. Classic case of keeping below the radar. I'm sure if someone did a video showing someone doing something stupid, they may get a knock on the door, but someone using an enclosed system is unlikely to have issues as these are inherently pretty harmless.
 
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Offline KE5FX

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Re: Faxitron MX-20 x-ray system teardown
« Reply #124 on: March 05, 2017, 07:18:07 am »
I don't suppose anyone has played with the RadEye sensors used by some of the MX-20s?  There are data sheets out there, but they're wrong in at least one respect (the frame-start input is active low, not active high).  Curious to hear what other surprises might be expected. 

Edit: this turns out not to be true.  Some other differences between the sensor's observed behavior and its data sheet gave rise to misleading measurements...
« Last Edit: March 28, 2017, 01:13:00 am by KE5FX »
 


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