Instrument is a Geonics EM16 VLF receiver, using in the mineral exploration industry to find buried linear conductors.
Give it the vinegar and baking soda treatment.
I greatly prefer citric acid. It comes in crystals so a small tub equals gallons of vinegar, it doesn’t smell bad, and you can control the strength by dissolving more crystals into water.
It’s incredibly fast compared to vinegar at cleaning battery alkaline.
To each his own. I’ve tried a few solutions. I use vinegar and apply it with some large cotton swabs. I usually wash them with the vinegar two or three times and let it sit for an hour. Then I use the baking soda dissolved into water and apply it several times. If possible to remove the contacts completely I will soak it in vinegar and then the baking soda solution. I buff the contacts if they are badly corroded. I can’t stress enough how much a little dielectric grease prevents further corrosion.
Neutralize the vinegar after dissolving the corrosion? I’ve not done that, but seems plausible.
It works. I’ve done it quite a few times. I have used a Dremel tool to buff the contacts and used a light coating of dielectric grease to prevent further corrosion.
Jul 91? Now I feel old.
The instrument is fully analogue, designed in the late 70s. The serial number on the device implies it was manufactured in 87. I contacted the manufacturer and the last person who could service it has long since retired, but they sent me the calibration and tuning documents so I might be able to revive this beauty.
What you got there, is spicy salt. Get all that flavor and mix it with some eggs. The cat in the hat ain’t got shit on it!
Protip: once you dissolve as much of the gunk as possible, take a small metal brush and give the contacts a scrub. If they’re coated, this helps open up metal contact surface to give the new batteries a chance.
But if the contacts are too corroded, you may need to MacGyver something with a soldering iron.
The whole battery mounting board is shot – entire traces corroded on it, and the contacts have effectively dissolved.
Fortunately, the machine was designed in 1977(ish) and batteries have gotten a lot better since. 6x AA batteries can now be replaced by a single modern 9V and it’ll deliver enough current. So I’ll mount a new 9V holder and solder it into the battery board wiring harness. I’ve already tested that solution on the breadboard and the machine appears to work.
9V batteries existed in the seventies. They just have far less capacity than six AA cells.
I agree. However the Ah capacity of a modern 9V is pretty good compared to the 70s. Unless you buy the cheapest 9V crap you can find ;)
please advise how to dissolve the gunk at home (using household items, cleaning products, or something that is available at local stores).
Someone said “use acid”, but I’m like “how the F am I supposed to get acid?”
Vinegar is acetic acid. Distilled Vinegar is quite useful as a general household cleaner.
Lemon juice contains citric acid.
CLR or a similar product that takes care of limescale (etc) is a mixture of acids.
Muriatic (another name for hydrochloric) acid is available from most hardware stores and can be used for dealing with rust.
Mild acids that are food grade are great because you don’t have to worry about occupational health exposure. A lot of people use vinegar. I use citric acid – which you can find in the grocery store in the spices section. Citric acid is what makes sour candies sour. You buy it as a powder.
I mix a little water and citric acid and let the part soak in it, then brush with a soft wire brush (not steel wire, as it’s too hard and will scratch the parts too much).
But, as a tangent, buying stronger acids is pretty easy, depending on the acid. Hydrochloric acid is sold in hardware stores as muriatic acid. Sulphuric acid is used to recharge lead-acid batteries. You’ll have a harder time finding nitric acid (because people can make explosives with it) or hydrofluoric acid (cause it is actually deadly as fuck), but industrial suppliers often have them. I wouldn’t handle any of these without some training. Even muriatic acid will off-gas chlorine and cause all the tools in your shop to rust if stored improperly. (From experience.)
Lots of good suggestions already, but you could also try oxalic acid aka Barkeeps Friend. It’s pretty mild and works wonders on metals.