8530F Plus Backscatter Detector Issue

[DavidAdams]

Hello everyone,

I'm having an issue with the backscatter detector on my new 8530F Plus and was wondering if other people have a similar issue and if so what was the fix? With all the travel restrictions and such going on right now it will probably be a very long time before I can get a JEOL service engineer from Australia to come for a service.

The backscattered image on my instrument will just randomly shut off in the middle of capturing images, simply navigating, or when acquiring maps. The only way I've been able to start it up again is to cycle through the different signals using the "VIEW" button. This is an okay solution when acquiring images or navigating but doesn't work well for maps as the map has to be stopped then restarted when the COMPO image is working again.

Has anyone else experienced this behaviour? If so do you know what was done, if anything, to fix it?

Cheers!
Dave

[Anette von der Handt]

Yes, I think all 8530FPlus BSE have that (I was told part of the "Plus" is a new BSE detector). They actually do not shut off but the link between contrast and brightness level is incorrect when you switch to a different gain level and the image goes pitch black because the brightness is so off.

If you use the mapping dialog in the JEOL software, you can actually read out the absolute values for contrast/brightness and see that. You will see that when the detector "shuts off" it changes the brightness level by an order of magnitude down, let's say from a 2000 value to 200. The correct value for brightness is somewhere between 50-30% instead of 10% of the original one. Cycling through the signals somehow seems to go to a different stored brightness level. If you just reduce the contrast, you usually get the image back as well.

I strongly suspect that JEOL is using the old settings for the previous BSE detector and didn't update the installation documentation for the new one but that is just my personal assumption.

Short term solution: Microscope light off (in case you don't already do that) when mapping and in general stay away from the transition point in the contrast levels either by going above or below the values in the settings. Charging (like porous samples that have not enough thick coating) exacerbates this behavior.

Long term solution: Talk to your old Denver service guy (Ken?). He fixed it on the Denver probe according to Heather. I haven't been able to do that yet on mine because the machine was so booked out. I assume that there are some hardware switches to set or something. I couldn't find anything in the software itself.

[Karsten Goemann]

We had the same thing that Dave describes. In our case JEOL replaced the BSE "mainamp" board (I think) and since then it is very rare and only happens if we hit something VERY bright (like strongly charging bubble in epoxy in a grain mount). And then we do the same - cycle through the signals to get it back.

Anette, that's interesting - I never noticed a link to the contrast/brightness. Do you mean when you change to a different contrast gain range (2000, 3000....)? Yes, the brightness totally changes between those, but I think what Dave means is that it just turns off without any change in brightness/contrast.

[DavidAdams]

Thanks Anette and Karsten!

I've seen the behaviour you describe, Anette, in both the probe in Denver (which was fixed somehow) and the new one here in NZ especially when trying to go towards very high contrast settings. The image absolutely blacks out and I have to go to the contrast and brightness sliders in order to turn the brightness up sufficiently to get the image back without having to turn the brightness knob many, many times! My issues is more like what Karsten described. I have a perfectly good image and during X-ray mapping + COMPO the image is acquiring just fine then with go black so I'll have a partial BSE image and completed X-ray map images. I have also seen this behaviour also when just navigating around and/or acquiring images. Since many of the samples I've been looking at are volcanic in origin I often get very bright bubbles and holes where charging happens because the carbon coating is lacking in those areas.

I will have to contact JEOL but if it requires a main board replacement then I suspect I will have to live with it for quite some time since the NZ and Australia borders are closed for the time being.

Thanks again!!