Radio Shack DX-397

I purchased this radio on Sept 11, 2001 while at OBX N. Carolina.  The other day I found it in a drawer "looking" in perfect condition.   It was playing beautifully on the FM band but when I switched to AM or any of the SW bands it stayed on the FM band!  Opening up th radio revealed a lot of corrosion on the PCB. A lot of delicate cleaning got all 12 SW bands working again, but I still have problems with the AM (Broadcast) band not working. I believe it is an internal antenna problem.  My question is; what can I put on the raw PCB so it will not corrode again? Is there a spray similar to the green coating already on the PCB?

This is the sort of material that is used industrially for the purpose. It has a uv tracer to show up for inspection io insure full coating.

http://www.ebay.com/itm/MG-Chemicals-4223-Conformal-Coating-Urathane-with-UV-Indicator-/120798765436?pt=LH_DefaultDomain_0&hash=item1c202ae17c

Thanks, that's what I'm looking for!  

I'll admit there are a lot of coatings you could use, but the next thing is to be able to get it off, if needed with the minum collateral damage. This allows that too, with the nature of the requsite solvents.

quote-Is there a spray similar to the green coating already on the PCB?-quote


My question is why did the green coating you said was already on there not working?
What do you think caused the corrosion? Batteries?
What kind of coating was it, or is it?
I have used fingernail polish to good effect. And Acetone as a thinner.
Just to make sure though, you should inspect the board for silver migration, and use and epoxy with a two part (Devcon is great). We did that when covering small trace repairs in military Printed circuits which was acceptable by MIL Specs.

I believe the corrosion was due to defective batteries. I may have removed the corroded batteries a long time ago and replaced them. ( I don't remember)  When I found the radio the other day it had batteries installed that were good. When it only received FM on all bands I decided to open it. The portion of PCB adjacent to the batteries was corroded. Delicate cleaning has it working again but but all the traces are raw copper again.

It is really a Sangean Sg622 with the Radio Shack name and is a great little radio.