right now going through this on a 15 year old JOEL JEM-1230 that had (or still may have) issues with its 68k VME based controller and with the original manuals and few very oblique notes from previous maintenance person, and I must say - without videos like these, those manuals are basically unusable... they don't mention which MAG modes to use, which "side" of crossovers to use, which apertures should be in and etc, I had seen it done once before, but this is first time doing it my own and without these videos I would have been lost thank you!
Great video, I am handling a similar instrument. I was surprised that you didn't do a rotation center, the pivot point, focusing binoculars and the beam shift. is it not necessary to do them for the gun alignment? Also, I noticed that for the gun tilt you used the central bright spot in the beam. However, I am told to fix it by using the multifunction X/Y knobs and ensuring that the screen current is maximum. Which one should I follow?
Thanks; you can also do the other alignments you mentioned, but the most critical are the gun shift and tilt; you can use the max screen current approach but what I've noticed is that this doesn't always end up with even illumination at high magnifications, so I prefer to center the spot.
@@NicholasRudawski Thanks so much for the quick response. I kind of get your point. I also like your approach of saving only the Gun shift and gun tilt in the FEG register and let each user play around with the other alignments such as rotation center and pivot point. I further noticed that you did the FEG register at Spot size 1 and without a sample. However, I cannot go to a lower spot size (
Thank you a lot for your video! One question: is beam centered for all intermediate spot sizes (in your example 2-5) or only for ss1 and 6 after gun shift alignment?
You're welcome; in principle, when the gun shift is properly aligned, there should be no beam shift for any spot size that is selected; however, in practice, there is usually some slight dependence on the beam shift with spot size. The Tecnais have an alignment called "spot size dependent beam shift" that attempts to compensate for this, but this is usually fairly minor so I didn't include it in the video.
@@NicholasRudawski Thanks! I work with the same model. I aligned the gun tilt/shift as you showed but in my case the beam was centered only for two chosen (frame) spot sizes, all intermediate spot sizes were not in the center. Do you have any ideas why? Thank you in advance!
@@kirillcherednichenko9193 I guess it depends on how deviated from center the intermediate sizes were; there will always be some hysteresis and the beam will never be perfectly centered when the spot size is changed even if the gun tilt/shift is aligned properly. I guess that's why they have the "spot size dependent shift" alignment to try and compensate for this, but even this in my experience doesn't work perfectly.
right now going through this on a 15 year old JOEL JEM-1230 that had (or still may have) issues with its 68k VME based controller and with the original manuals and few very oblique notes from previous maintenance person, and I must say - without videos like these, those manuals are basically unusable... they don't mention which MAG modes to use, which "side" of crossovers to use, which apertures should be in and etc, I had seen it done once before, but this is first time doing it my own and without these videos I would have been lost
thank you!
Hi jz1199: you're welcome, glad you find the videos helpful.
Great video, I am handling a similar instrument. I was surprised that you didn't do a rotation center, the pivot point, focusing binoculars and the beam shift. is it not necessary to do them for the gun alignment? Also, I noticed that for the gun tilt you used the central bright spot in the beam. However, I am told to fix it by using the multifunction X/Y knobs and ensuring that the screen current is maximum. Which one should I follow?
Thanks; you can also do the other alignments you mentioned, but the most critical are the gun shift and tilt; you can use the max screen current approach but what I've noticed is that this doesn't always end up with even illumination at high magnifications, so I prefer to center the spot.
@@NicholasRudawski Thanks so much for the quick response. I kind of get your point. I also like your approach of saving only the Gun shift and gun tilt in the FEG register and let each user play around with the other alignments such as rotation center and pivot point. I further noticed that you did the FEG register at Spot size 1 and without a sample. However, I cannot go to a lower spot size (
Thank you a lot for your video! One question: is beam centered for all intermediate spot sizes (in your example 2-5) or only for ss1 and 6 after gun shift alignment?
You're welcome; in principle, when the gun shift is properly aligned, there should be no beam shift for any spot size that is selected; however, in practice, there is usually some slight dependence on the beam shift with spot size. The Tecnais have an alignment called "spot size dependent beam shift" that attempts to compensate for this, but this is usually fairly minor so I didn't include it in the video.
@@NicholasRudawski Thanks! I work with the same model. I aligned the gun tilt/shift as you showed but in my case the beam was centered only for two chosen (frame) spot sizes, all intermediate spot sizes were not in the center. Do you have any ideas why? Thank you in advance!
@@kirillcherednichenko9193 I guess it depends on how deviated from center the intermediate sizes were; there will always be some hysteresis and the beam will never be perfectly centered when the spot size is changed even if the gun tilt/shift is aligned properly. I guess that's why they have the "spot size dependent shift" alignment to try and compensate for this, but even this in my experience doesn't work perfectly.
@@NicholasRudawski thanks again!
The manual suggests iterating between spot size 3 and 9 as that gives a 'ribbon shape' to the deviations resulting in the least deviation from center.
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