Ciruit Board Protection

Page 2 of 2  
On Wed, 16 Nov 2011 21:29:39 -0600, Michael Dobony

cure coatings.
MG's product will room temperature cure in 48 hours, or it can be heated to speed it up. Dow Corning makes Room Temperature Vulcanizing elastomeric and Elastoplastic as well as solventless heat cured products. Nordson also produces UV, Heat, and Air Dry products.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Krylon makes an electical coating this should not be confused with clear Krylon. Board should be cleaned before it is applied or you may trap in corrosive material. already on the board.. Plug in connectors should be masked off to keep the Krylon out of the connectors. Use a little electrical grease on the connectors. The grease can be obtained at local automotive parts store. They sell it in little packets for greaseing up turn signal and break light bulbs.
Jimmie
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Michael Dobony wrote:

http://www.americanstandardair.com/Products/Pages/productsCategory.aspx?cat=Packaged+Systems All our A/Cs have been packaged systems, but I don't think their circuit boards ever rusted much, although we're in Phoenix. I saw only one of their circuit boards, a defrost controller, and I don't believe it had any protective coating on it. So is it possible your board wasn't grounded adequately? Or would it help to attach its chassis ground to some zinc, even just galvanized screws?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Home Guy wrote:

In any repair situation, it's important to fix the thing that's broke. Any product designed to sit outside MUST be capable of withstanding the environment. Unless you're near an ocean, your environment is likely way less corrosive than the design/test environment.
I'd call the vendor or the installer and see what they have to say about it. Then I'd look at how the board is configured and make sure the enclosure isn't missing a gasket, or bent, or has an open screw hole in it. Seal it up tight. Make sure it's dry inside when you're done.
Conformal coating seems attractive on the surface. Of course, it's gonna void the warranty and make the board very difficult to repair. It has thermal resistance, so any component depending on convection cooling will be compromised.
If you decide to clean it, be aware that some components may not like being drenched in alcohol and water.
Spraying the board in place may not be effective. You need to seal the back and the edges of the board.
If you decide to coat it, dry it as discussed above, then dry it again. Doesn't do a lot of good to keep out the water when the water's already under the coating.
Still think I'd seal the enclosure first.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 16 Nov 2011 16:04:27 -0800, mike wrote:

LOL!!!!! The panel covering it is held on with two screws and the cover has no gasket and is ventilated to the outside. It experiences the same atmospheric conditions as exist outside, like an open porch with open horizontal blind style windows. To seal it up also would seal up the air from the furnace burner.

Total reengineering and moving the board to a totally new location.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Michael Dobony wrote:

Sounds like you've got a very bad design, or have installed an "inside" box outside where it doesn't belong. What does the vendor/installer say about it?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 16 Nov 2011 20:17:09 -0800, mike wrote:

Bad design and $5,000 to put in a new one that might have a better design. It belongs outside. Take a look at the link.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 11/16/2011 2:45 PM, Michael Dobony wrote:

http://www.americanstandardair.com/Products/Pages/productsCategory.aspx?cat=Packaged+Systems
Rust on diode leads is quite surprising as even the high current diodes with steel wire leads have a solder coating (tinned leads). Perhaps the leads were damaged during assembly or testing and the coating was broken.
If you can turn the power off and get to the leads, I would suggest cleaning off the rust and retinning the leads with a soldering iron and rosin core solder.
I had our heat pump serviced last week and watched the young man as he did his work. The circuit board controller is like yours, outside on the heat pump and and under a metal cover that protects it from all but blowing snow. Quite a bit of dust, but no other problems. The board does have three 2 watt resistors that have discolored the board from their heat. They should have been placed further from the board material.
Such heat producing devices are one good reason not to conformal coat the circuit board. Or they need to be masked so coating material is kept away from the resistors.
My electronic assembly company is required to conformal coat several different circuit boards. In most cases we use urethane applied with a brush and carefully avoid the locations the customer wants to not be coated. Connectors, switches, sensors, test points, and mounting holes.
Other customers have specified the silicon based coating. Both coating material is rather expensive. Much of it is ONLY available in metal one gallon cans because bottles can't be shipped UPS. Urethane is available in spray cans, but most cans are plugged up and won't spray, even right from the distributor. Shelf life is almost zero. There is no return on conformal coating material.
Paul
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paul Drahn wrote:

Orientation of board is important as well. Right side up, on vert. vs. horiz. plane exposure to the element or under ventilated cover, etc.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 16 Nov 2011 22:32:33 -0700, Tony Hwang wrote:

Vertical orientation. The old board had rust running down from one connection to the next, about five or six connections gone. It was in there two years unused. Now I have freezing weather and can't wait for shipped unit. If I have to replace it again it will cost double what I can find on the internet.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I would normally talk to company for possible fixes. Sometimes we have to try to get the company to do a fix. They like a certain amount of repair in their products. Even if board is good, connectors will still have problems.
Greg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.