Author Topic: Atlas Tear-Down Photos  (Read 2631 times)

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Offline DoctorKnow

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Re: Atlas Tear-Down Photos
« Reply #25 on: January 22, 2019, 08:32:28 AM »
Quote
I was imagining 5n1 wind-cup type tightness, but the vane and cups pulled off without immense force.  I didn't notice any grit, but I did notice what looked to be graphite on the tip.
The grit I was indicating was just dirt, or sand that must have blown into those ball bearings. The anemometer is spinning like brand new now that I lubed it, even better than the new one on the Atlas I was sent for Christmas. When I put the lube on the bearing, and spun it by hand, the first few spins you could hear the dirt in them, and then as you kept spinning it, it was very smooth, and loose like it should be.
Thanks for the pics. It shouldn't be hard for users to lubricate theirs if needed. The hardest part for me was putting the direction indicator back on the spindle. Getting it on with the flat side of the spindle just right was a little tedious.

Online nincehelser

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Re: Atlas Tear-Down Photos
« Reply #26 on: January 22, 2019, 12:13:37 PM »
Seems there is always something more to dig into...

Here's the UV module.  The wiring is not removable, but you can remove the module from underneath the black upper assembly with only two screws.  Note the yellowing due to aging, some have been concerned about if this is a problem or not.

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The cap of the module can actually be removed with another two screws.  Note the white insert and foam circle.  I assume the white insert must be some sort of filter.  I'm not sure about the foam circle function... maybe to prevent light from the side?  It seems unlikely that it is for water protection.

The sensor chip is an Si1133.  More info about that here: https://www.silabs.com/documents/public/data-shorts/Si1133-DataShort.pdf

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Offline DoctorKnow

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Re: Atlas Tear-Down Photos
« Reply #27 on: January 22, 2019, 12:20:05 PM »
Mine has yellowed as well.

Online nincehelser

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Re: Atlas Tear-Down Photos
« Reply #28 on: January 22, 2019, 12:27:47 PM »
Mine has yellowed as well.

I've been looking at the application note: https://www.silabs.com/documents/public/application-notes/AN968-Si1133-UV-Index-Sensor-Electrical-and-Optical-Design-Guide.pdf

It states that the "overlay" can't have a UV stabilizer.  I guess that's why it is yellowing, and makes sense since you're trying to measure UV.  I'm still unclear if the yellowing is a problem, but as long as there is less than 50% attenuation, maybe it doesn't matter.

The white dot is what they call a diffuser which results in better readings.  It's probably a thin dot of teflon tape.


Offline radioman61

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Re: Atlas Tear-Down Photos
« Reply #29 on: January 22, 2019, 04:19:15 PM »
I think the foam ring is to keep any refracted light from getting to the sensor

Offline vreihen

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Re: Atlas Tear-Down Photos
« Reply #30 on: January 22, 2019, 06:54:03 PM »
A lot of materials including most window glass block some UV.  The white dot is most likely a teflon or other UV-transparent window, and the foam is to make sure that stray light from the rest of the cover does not hit the sensor.

They could have used UV-protected plastic for the rest of the cover, but probably saved a few pennies per component by leaving it untreated.....
WU Gold Stars for everyone! :lol:

Offline daman

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Re: Atlas Tear-Down Photos
« Reply #31 on: January 23, 2019, 11:02:29 AM »
Could a guy put a UV protectant on it when its new or would that interfere?
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Online nincehelser

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Re: Atlas Tear-Down Photos
« Reply #32 on: January 23, 2019, 11:37:41 AM »
Could a guy put a UV protectant on it when its new or would that interfere?

You wouldn't want to get any on the circle area.  You can't measure the UV properly if it is being blocked.

Makes me wonder about some of the suggestions about using car wax or other such products on weather stations.  It's probably best to avoid putting such things on UV sensors.

Offline daman

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Re: Atlas Tear-Down Photos
« Reply #33 on: January 23, 2019, 11:53:38 AM »
Yea that's what I was wondering like a UV protectant wax or something.
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Offline giveme5

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Re: Atlas Tear-Down Photos
« Reply #34 on: January 24, 2019, 03:55:06 PM »
Does anyone know whether the Atlas aspirating fan blows upward or downward?

Online nincehelser

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Re: Atlas Tear-Down Photos
« Reply #35 on: January 24, 2019, 07:02:47 PM »
Does anyone know whether the Atlas aspirating fan blows upward or downward?

It should be blowing up, pulling fresh outside air over the sensor.

Offline giveme5

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Re: Atlas Tear-Down Photos
« Reply #36 on: January 24, 2019, 07:55:48 PM »
It should be blowing up, pulling fresh outside air over the sensor.

Thank you!


Offline DoctorKnow

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Re: Atlas Tear-Down Photos
« Reply #37 on: February 02, 2019, 05:16:16 PM »
Underside of rain bucket assembly.  This houses the 3 solar panels and the UV/Light intensity sensor.

http://www.wxforum.net/index.php?PHPSESSID=ce6f1a1efb38385380a3cf5fe09aaebb&action=dlattach;topic=35220.0;attach=33227;image




If you take out those two screws that hold the piece in behind the south pointing solar panel, (to the right in pic) there is a board under it with a capacitor. This is where I found my issue on the Atlas I have that dropped signal on the Access out of sunlight. Apparently there is a poor connection on that board. I fiddled with it, and now my signal isn't dropping out permanently, but is still missing some transmissions...

What I need to do is swap rain buckets and see if the issue goes away entirely.
« Last Edit: February 02, 2019, 05:18:33 PM by DoctorKnow »