Anyone here knows about X-rays????need help here

[tankee]

anyone working in X-rays field??? i need some help and teaching from experts.....all my seniors won't teach me....job security issue...anyone can help?

[haklesup]

What area of expertise? Service and maintenence, alignment, interpretation of micrographs, medical imaging, security imaging, backscatter imaging, non destructive component inspection, F/A, QRA, theory, general questions, etc. Few persons would be able to comment in all areas.<p>Are you in a Semiconductor F/A (failure analysis) lab?<p>In the microelectronics applications, training usually comes direct from the equipment vendors since there is no universal user interface and capabilities vary greatly. Search all equipment vendor websites (including those for whom you do not have equipment) for application notes and manuals. The local sales reps may protect your seniors job like it were their own. I know Singapore can be a very small community when it comes to jobs and relationships rule.<p>If your questions are direct and intellegent, you can pose them directly to the apps engineer at the equipment vendor by email usually.<p>Check out this website of my close business associate in Korea www.amfis.com (he wants to establish factory in US and partner with me but the talk is going on years now, may never happen)

[MicroRem]

i work in the security screening eqipment field, specifically conveyurized cabinet X-ray systems as well as metal detection and trace detection equipment, but I'm not sure how much help I could be, except to answer specific questions. I don't think conducting a class via web posts will work. I do suggest moving cautiously since the typical x-ray system contain plenty of lethal voltages and assorted other ways of injuring the uninformed but well intentioned.<p>regards<p>tom

[tankee]

do anyone have any web site in repairing n troubleshooting?

[Dave Dixon]

Repairing and troubleshooting WHAT???
I'm sorry, but as noted, more details PLEASE!
With all due respect,
Dave

[tankee]

repairing n troubleshooting of x-ray? if not power supply ?

[Dave Dixon]

Not to be rude, but:
With this info, all I can advise is that you make sure it (whatever it is) is plugged in, and that
the circuit breaker is not open. I'm sure someone here would love to help you.
Help me out here guys!!!
Dave

[jimandy]

Assuming that this topic is real, "learner" should tell us if he's talking about medical radiography, fluoroscopy or x-ray therapy. In any event, machines for those specialties involve extremely high voltages and no one except a trained specialist should be working on them, let alone a "learner". The obvious point is that it is dangerous for the service tech, but less ovious and more important is the safety of the patients!<p>I would think that in most bona fide medical facilities no one would ever be let near the innards of an x-ray machine unless they are an authorized manufacturer's technician.

[terri]

Dave, hacklesup, jimandy:<p>I am re-posting this from another topic by "learner" for your consideration:<p> posted March 22, 2005 05:52 AM
--------------------------------------------------------------------------------
My Brooklyn "Street Paranoia" suggests that maybe we're being strung along. I note that 01 Apr is approaching.<p>I am of a most helpful nature, having been in situations where I needed outside help to solve a problem thrust upon me, but this constant feeding of non-information and garbled-de-gook sure sounds like it's time for the forum members to review the situation in that light.<p>I personally would love to help, learner, but unless hard, firm, coherent, no-nonsense information is forthcoming, I for one am not going to deal with this question, and haven't since my initial point-by-point request for more data.<p>For information on how this "stringing along" can be accomplished, see the below link (Dogpile is my preferred search engine). Some of these, where the "scamee" scams the scammer, are delightful.<p>http://www.dogpile.com/info.dogpl/searc ... Bscam%2522<p>Also sprach Terri<p>[ March 22, 2005: Message edited by: terri ]</p>

[haklesup]

Terri,<p>I recognize your suspicions but at the risk of sounding "non politically correct" I can comment that it is actually quite common to have support conversations with persons from that part of the world that go this way.<p>SO often I am frustrated when my detailed list of instructions are ignored only to be responded with the results of an unrelated procedure and a restatement of the original question. It dosen't matter if it is my sales rep's service engineer whom I have trained and emailed for years or an experienced engineer in a big company. it happens anyway.<p>Fortuantely they usually do "get it" after several attemts.<p>In do recall another member of this forum who now posts good questions and comments but originally posted questions of the same level and quality as learner. I had emailed with this person (overseas) for several months (about a year ago) and now his posts appear to reflect that he knows what he is doing now. <p>I agree we are done guessing and learner needs to come up with some substance to continue.

[terri]

OK. I sincerely and truthfully hope my suspicions are unfounded. <p>But there is a pattern there with which I personally do not want to deal. If you will note, I was very patient with the cutting disc querent a while ago, even with the language difficulties there, and apparently finally got some resolution with his problem of "hoursepower." But that was a "hourse" of a different color. This one has a different smell to it, in my mind. Not like a "hourse" at all. More like a woods pussy.<p>Again: I hope I am wrong. Go for it, if you like. Good luck.<p>[ March 22, 2005: Message edited by: terri ]</p>

[Dave Dixon]

This reminds me of the guy who took his television into the repair shop and told the
technician it was "broke". The technician asked the customer to please be more specific. The reply...
"My Sony 19" Color Television set is broke". Geez!
Dave<p>[ March 22, 2005: Message edited by: Dave Dixon ]</p>

[tankee]

guys i am sorri for my rudness......pls correct my attitude....bt this is my 1st job after a graduate n and i wish to strive the best.....<p>one question...today my x-ray generator down my senior just took a multi meter and probe measure on the IGBT and tell me is faulty....i ask him how to measure an IGBT he said only is hard make sure u probe on the correct gates...if if it will short the IGBT while the power is on..<p>is ter a way to measuring IGBT? npn .,,pnp? cant i just measure across i/p or o/p?

[haklesup]

OK, that's better. Now what I am hearing is that you want to learn some troubleshooting techniques for identifying bad components. In particulat how to ID a bad IGBT.<p>To test a circuit powered up, you must know how it works. Usually this requires a schematic and a good general understanding of electronics. No offence but it seems you lack both at this point so lets move on to testing a system while powered down.<p>While powered down, you need not worry about voltages and current measurements, almost anything you need to learn can be dome with an ohmmeter.<p>In many cases you can make measurements on a component in circuit as if it were out of circuit but other times the measurement will be a combination of that from several components in the circuit if they are in parallel. A schematic helps but so does looking at the copper traces on the PCB.<p>Resistors should have the value indicated on the package.<p>Capacitors should be open circuits but may read some resistance for a few moments after you apply the meter probes.<p>Diodes will have resistance only in one direction<p>NPN and PNP transistors are tested like they are two diodes on one package. probe from B to C and B to E and in reverse of that. You should get resistance in one direction only. From C to E it should be open always. <p>For a FET device first probe D to S and it should be open in both directions then probe G to D and G to S and the G should always be open. After probing the G, go back to D and S and it may not be open anymore (Depends on which polarity you probe the G and if the FET is PMOS or NMOS) because the voltage from the probe can turn on the transistor.<p>I looked up IGBT device spec sheet and found out that it is basically a combination of an NPN power transistor and an NMOS transistor in kind of a totem pole arrangement. with the Base and Gate driven by an opto isolator. The one I looked at was in a DIP-08 package but was essentially a 5 terminal device. Two pins are for the input LED (Anode and Cathode) test those pins like a regular diode. The other three pins should probably be open unless powered up and biased at the input LED so expect opens at every other pin.<p>I would guess that your senior simply probed the pins of a good device many times and already knew what to expect. When he probed the bad device and found a short where it shouldn't have been he assumed that was the only bad component and went on. Experience again is what probably told him he needn't look further. You should not assume that is the only bad part though. When one part fails, it usually takes a few buddies with him.

[haklesup]

Oops, the link in the above post is for an IGBT driver IC. Here is another link for a deviceIGBT<p>It is three terminal device (E, C, G) and probably looks like a FET when probed except you probably cannot turn it on with the probe. <p>In any case, probing adjascent good devices or ones on a known good equipment will show you exactly what to expect.<p>THe above link is actually a good app note on IGBT devices and probably tells exactly how to test but I did not read all 29 pages. homework for learner