You might not need that information.
Before you try to replace them, try this. Wash both sides the board in the affected area with a soft toothbrush and warm soapy water. Rinse it with 90% Isopropyl Alcohol (from your local pharmacy - don't use the 70% unless you absolutely must). Blow it dry with a cheap hair dryer but don't get too close with the hot air.
Inspect the board traces (the copper under the green paint) to see if any are broken or corroded through. The white stuff you see is also shorting the pins together acting as a conductor so be sure the pins on all of the ICs are separate and free of corrosion. Look closely to see that the solder is not compromised. If it is, brush some flux over it and heat it to reflow it. When doing so, be careful that you don't create any new solder bridges. You might have to add some small amount of solder so use the smallest diameter of multicore solder that you can get.
If any of the traces are broken, you will have to fix them by scraping the green paint off and adding a tiny bit of wire to reconnect the gap. You can use ordinary zip cord (the stuff that you use for speakers that zips apart when you pull it) but only use one strand of the wire holding it in place with tweezers as you solder it. An inch of wire will break into dozens of strands of PC board repair wire.
If any adjacent traces are shorted by the corrosion, you will need to separate them by scraping away the corrosion with an X-Acto knife and then making sure the traces are truly separated.
Be sure to look closely at both sides of the board in the area of the corrosion using a magnifying glass. Look underneath the chips to be sure there's no corrosion or stuff growing there. If so, use a slice of a business card or a plastic collar stay to push it out. Nine times out of ten, your corrosion control treatment will fix everything up just fine. If this works, you might spray the board with either clear acrylic enamel or cheap hair spray. Hair spray is diluted lacquer and will work in a pinch.
Good luck. Let me know if this worked for you. And always remember that your detector's shaft is a water pipe from your coil to your control box. Your coil may be waterproof but when you get it wet, the water goes up the pipe to your nice, shiny, green PC board.
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« Last Edit: January 23, 2011, 05:00:22 am by GoldDigger1950 »
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It's all about that moment when metal that hasn't seen the light of day for generations frees itself from the soil and presents itself to me.
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