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How to cure the dreaded damp USB problem?

michaelmorris

By michaelmorris
in The Astro Lounge

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michaelmorris

michaelmorris

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Last night was clear and I took the opportunity to grab some more OIII data for IC1396 (The Elephant Trunk Nebula).  However, I lost about 50 minutes of imaging time because my PC said the that the Lodestar guide camera wasn't getting enough power.  Swapping over two USB leads solved the problem.  Of course, I check it again this morning with the original USB leads and all is fine.

Last night was the first night of the season when I've had frost on the roof of the observatory, so I suspect the issue was water condensing on the contacts of the USB lead and/or USB sockets.  I often get similar problems when imaging at star parties.  Is there a way to prevent or cure this problem or am I wishing for the impossible?

Thanks

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symmetal

symmetal

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I just spray all the contacts with ACF-50 once a year and never have any connection problems. Just wipe off any excess that ends up on the connector body (it does no harm but ends up on your fingers and feels a bit oily.) It's used in the aviation industry for coating circuit boards and switches and also removes any corrosion that has built up previously. It's not cheap but one spray can will last a very long time.

It's probably best to apply it when the connectors are dry as it prevents moisture contact with the metal, but doesn't say it displaces water already present.  That may interfere with its mechanism for providing the anti-corrosion coating. Edit - Actually reading the above link it does say it displaces moisture so it could be used on damp connectors.

It has no effect on paint or plastic so I just rub a cloth sprayed with ACF-50 over the mount so stop bits going rusty. Spraying it over my Lakeside focusers stopped any corrosion that was beginning on the motor body and DB9 connectors.

Alan

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symmetal

symmetal

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Thanks Gav. :smile:Yes. Shake the can and spray into the USB ends where the contacts are. Let the excess drip out and then wipe down the outside. Plugging the USB lead in at first  it may feel a little looser as the spray is also a lubricant but it's always best to have the cables tied off somewhere so that there is no permanent strain on the connector trying to pull it out.

Alan  

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PhotoGav

PhotoGav

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11 minutes ago, symmetal said:

Thanks Gav. :smile:Yes. Shake the can and spray into the USB ends where the contacts are. Let the excess drip out and then wipe down the outside. Plugging the USB lead in at first  it may feel a little looser as the spray is also a lubricant but it's always best to have the cables tied off somewhere so that there is no permanent strain on the connector trying to pull it out.

Alan  

Thanks for that. Can you recommend an online supplier, please?

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Carbon Brush

Carbon Brush

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Hi. A suggestion to help with astro-electronics in general if I may?

Much commercial quality 'computer' equipment works on the basis of being used in a heated dry room. This is everything from desk/laptop computers, monitors, USB cables, assorted adapters.

In most astro packages the only component I would not expect to show problems is a proper astronomy camera.
This is on the basis that the manufacturer expects cold and damp conditions.

A bit of grease on USB contacts is a good idea. But of course if you have anything with electronics in the USB line (splitter/hub etc) then the circuit board as a whole may be susceptible to condensation.
Then of course the computer has at least one large circuit board that may be susceptible to condensation.

Add to this a laptop or desktop may not work very well when cold due to temperature drift in circuit characteristics.
Computer DRAM is well known for this and properly written BIOS includes temperature compensation on RAM timing.

A hint of condensation on the radio frequency bits of wireless kit is enough to upset it.

Examples of flaky commercial kit I have at home include a router that stopped working until the summer heat wave ended. A monitor in my observatory that has a few fixed colour vertical rows if not run (to heat) for a couple of weeks.

As a general rule, anything with significant self heating, like a laptop, will eventully dry and work.
But low power consumption devices may not produce enough heat to dry, or climb into the temperature range for correct operation.

Something to do on a cloudy night. Stick the equipment in the freezer and see if it works to -18C.
Then bring it into your warm humid house to introduce condensation.
If it survives this, you will have no problems on a clear night.

Hope this helps, David.

 

 

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PhotoGav

PhotoGav

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3 minutes ago, symmetal said:

I just ordered it from Amazon Gav. It was a motorcycle dealers that supplied it. It's £15.99 a can or thereabouts. There are plenty of suppliers on ebay too. Again, mainly motorcycle dealers. :smile:

Alan

Thanks Alan.

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symmetal

symmetal

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When I made my imaging box attached to the dual scopes I mounted the mini PC and USB hub well inside the box and cut slots in the imaging box just large enough for the connector body to fit through. The heat from the PC is enough to keep all the connectors dry. A bonus is the connector sized slot prevents the connector moving about much.

Alan

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symmetal

symmetal

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Here's a few tips on using ACF-50, written for motorcycles, but half way down it does say about applying it to electrical contacts. It says it's best to use it when the can is at room temperature as the propellant works better. I've had it come out like foam on occasions. :smile: A thin coating is all that's needed so I normally spray it into a USB plug and then plug it into the sockets a few times to transfer the film to the socket contacts. Plus all other plugs and sockets of course, but USB ones are the most vulnerable to moisture and poor connections.

Alan

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Stub Mandrel

Stub Mandrel

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23 hours ago, Carbon Brush said:

Something to do on a cloudy night. Stick the equipment in the freezer and see if it works to -18C.
Then bring it into your warm humid house to introduce condensation.
If it survives this, you will have no problems on a clear night.

And if it blows up, buy some decent kit :evil4:

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  • 2 weeks later...
michaelmorris

michaelmorris

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On 15/10/2018 at 19:51, Jonk said:

I would imagine that it also helps rain to run off of all sky camera domes.

It does the same for motorcyle visors.

or try the version of Rain-X designed for use on plastics?

https://www.amazon.co.uk/d/Car-Window-Cleaning-Products/Rain-84199500-Plastic-Water-Repellent/B0747VTBJT

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