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rohitshakti
08-05-2017, 10:13 AM
Hi

I have a sharp Inverter AC and am using it for the last 3 years but recently I have heard that many PCB have blown as we have a big drainage near our house which when corrodes the copper, PCB blew away and after that its repair is very costly.

I have read that spraying anti corrosion spray on AC PCBs help them to stay longer and delay corrosion which is done due to sea, moisture/humidity and corrosion due to bad smells of drainage systems.

Corrosion is like an atom bomb for inverter ACs as nobody knows when it will explode and destroy the PCB of the AC. For protecting the PCBs and similar components, anti corrosion spray or Conformal Coating or Clear Lacquer is used. I want to know the following:

1. Which one of these or any other is better for protecting PCBs?

2. Are there any disadvantages of using these sprays?

3. How can we use these sprays on PCBs?

4. What type of cleaning of PCBs should be done beforehand of using these sprays?

5. Precautions needed?

6. Lastly the airflow in my AC is very low, what can be the reasons for less airflow as we get good flow if we sit near 5-6 feet only else we donot get air, pls help....

Has anybody used any such sprays and if yes, how long it was effective?

Regards

still learning
08-05-2017, 09:59 PM
I know of a ac unit on a boat that is in our harbour and goes to sea in quite rough weather it has a couple of enclosures around it to stop the action of large waves dumping on top of it and is a very salt ladder air around it.
from new we removed the pcb and sprayed lacquer underneath where the solder can be seen painted the bace and fan motor bracket put extra silicone sealer. Around. Areas where wiring enter the outdoor fan motor . I will hazard a guess that it lasted about five years or so.
this time the compressor was ok . So it has a new board and fan .
a uk company called rs supplies sell a can of spray lacquer , but I think it's possible to get the same thing in India as the repair of electrical items is quite common.

still learning
08-05-2017, 10:05 PM
As for your air flow , i take it that your filter on the indoor unit is clean.
but look at your fan impeller.
see if you can scrape any dirt from it, it may help to clean the indoor coil .
The size of your room that you are cooling plus the humidity could also. Be a issue .
Good luck

rohitshakti
09-05-2017, 08:32 AM
Thanks for the reply. I have been suggested to rinse the PCB in something like isopropyl alcohol for cleaning, let it dry, mask it and then spray the coat. Any idea what is masking?

And will this spray work on PCB?
1478914790

rohitshakti
09-05-2017, 09:38 AM
Will this spray work on PCB for its protection?
1479114792

still learning
09-05-2017, 11:13 AM
Hi thanks for the product picture .
i would not use the pictured product.
to me it looks like a coating that you would spray your out door coil with to slow down corrosion .
if you use this you could blow your pcb board,I would say it had a high metal content.
the product you want is very similar, to the clear lacquer that car sprayers use .
but I am not sure that it is possible to send you a picture of the product we use.
That I why I said to try the television repair man. And see if he had any spray ,or the computer repair man .

Masking by the way is when you use tape and newspaper to cover up the things you don't want to use.

Greek_engineer
10-05-2017, 07:44 PM
with these products there is great possibility to blow up the pcb.
what about that?
http://uk.rs-online.com/web/p/electronics-varnishes-lacquers/1247681/

malik55
10-05-2017, 11:39 PM
Apply lacquer warnish spray on both sides of the PCB, Leave the Heat sink components if any is there. Apply 3to5MM layer of good quality Silicone sealant on back side of the PCB Board, Seal all control box opening wire entrance holes, Panel cover and Screw ends back side with same sealant, Do not left any opining at all. Hope this Silicone Sealant Compound is available in your country.

malik55
10-05-2017, 11:48 PM
For Low air problem it is not sure how much air is delivering by this fan, for that we have to measure it by a device called Air Velocity Meter and compare with the manufacturers data . You can only do clean the filters, Wash the indoor coil and blower assembly, If indoor service has not been done so long you will get a good difference.

still learning
14-05-2017, 06:09 PM
The rs product from. Greek engineer to me looks like a coating. That would be used if you had a break in the solder on a pcb .

Malik 55 is on the. Right track with the varnish spray .