Water in my relays - Page 1
Forum section: electronics / projects

author: itdontgo
author_rank: Regular Contributor
timestamp: February 19, 2015, 12:38:53 pm
content: Our boards have just come back from the assembler with an impedance between the NO/COM terminals. There is water in the relay from the washing process. Seems Omron's sealed relays have a little hole in them. Back to Songle in future!I've had some reworked with new relays. I've cracked a few open and they're not flooded but they contain droplets here and there. Would you trust a relay that's been filled with water even if it eventually evaporates?My plan is to stick them all in a container filled with silica gel

author: tom66
author_rank: Super Contributor
timestamp: February 19, 2015, 12:41:36 pm
content: There would certainly be a risk of isolation failure between the coil and the relay terminals if that is important to you.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: February 19, 2015, 12:53:39 pm
content: That bring some memory for days i was wondering how the hell the relay was conductive without any voltage on the coil, so i cracked them open too. an omron relay, they are extremely dangerous , the design i was working on , run on main voltage and the relay was conductive even when not energized, lethal voltage can be measured on the output.They don't need to be flooded, the NO-COM contacts being too close to each other can keep a tiny amount of water between them.

author: Pjotr
author_rank: Frequent Contributor
timestamp: February 19, 2015, 01:08:39 pm
content: The Omrons are of excellent quality but you need to choose the right one for the purpose. It was not probably a "washable" type? Usually the washables with a hole have the hole taped off for assembling and washing. Something went wrong there at assembling?

author: cosmicray
author_rank: Frequent Contributor
timestamp: February 19, 2015, 02:24:54 pm
content: Quote from: itdontgo on February 19, 2015, 12:38:53 pmHow large are the boards ?The common solution when consumer electronics take an unexpected bath, is to put the item in a zip-bag with a quantity of (raw uncooked) rice. The rice being presumed to attract any excess moisture that might be lurking around. This is more likely to work if the spillage was water (not sticky soda) and the electronics was not powered during the mishap. Might be worth a try with one board, as a comparison to other methods.

author: ElektroQuark
author_rank: Unknown
timestamp: February 19, 2015, 02:49:21 pm
content: Wash them first with distilled water. It will keep away with the posible soluble deposits. Then you can dry them.

author: Cloud
author_rank: Regular Contributor
timestamp: February 19, 2015, 03:09:29 pm
content: I am no expert, but what about washing them in a ethanol 90+%? Because it will displace water and then it will evaporate.

author: calzap
author_rank: Frequent Contributor
timestamp: February 19, 2015, 03:34:47 pm
content: Quote from: Cloud on February 19, 2015, 03:09:29 pmEthanol is flammable, forms explosive vapor in air, and is an organic solvent. It would be hazardous to use in the first place. If particular proportions of ethanol vapor and air remained in the relay housing, it could become a grenade when energized. The ethanol might damage other components or remove identifying marks. Not saying it won't work, but if it's going to be used at all, try it carefully on one piece first. That said, I've used ethanol many times as a drying agent on lab glassware with excellent results.Mike in California

author: ElektroQuark
author_rank: Unknown
timestamp: February 19, 2015, 04:06:53 pm
content: Quote from: Cloud onTodayat 03:09:29 AMPart of the water soluble deposits, or all of them, can be not soluble in ethanol.

author: MK
author_rank: Regular Contributor
timestamp: February 20, 2015, 07:30:06 am
content: First wash with distilled water to remove any salts present, then wash with pure Iso-propyl alcohol then dry with a hair dryer, used that on many production PCB's that initially failed for various reasons, always came out clean.

author: pickle9000
author_rank: Super Contributor
timestamp: February 20, 2015, 07:38:22 am
content: How long have they been wet. If not completely wet then you can have oxidation issues.As a general rule if you ask the question and it's critical (remote control toy car vs gas valve) then you need to change them.

author: free_electron
author_rank: Super Contributor
timestamp: February 20, 2015, 03:17:37 pm
content: certain washable relays have a little peg on their top. that peg needs to be snipped OFF AFTER washing. this creates a ventilation hole so the relay can dry out.