Need Help Repairing Old PCB

[kbrooky]

I collect old vhs, and recently got some cool gimmick ones that light up when you press a button. However, they are almost 30 years old and no longer work.

Taking a look at the pcb both were heavily corroded. I scraped off as much green corrosion as I could and replaced batteries but no luck. Now I'm stuck on what to do.

1. Part of the lead came off on one (green corrosion is underneath as well), is this fixable via soldering?
2. How can I clean the corrosion off any better?
3. Can these be fixed, or are they beyond repair?

What it should be when working- https://www.youtube.com/watch?v=Ax5QVMSjAEg

 

[Diver300]

What part has come off? If it is the connection between the batteries, you can just solder a wire between the +ve of one battery and the -ve of the other one.

 

[cowboybob]

Welcome to ETO, kbrooky!

First thing is to carefully clean the PCB traces with some "Contact Cleaner" (or at the least, distilled water) and a soft bristle brush to get rid of any remaining corrosion and the acid causing it. Hopefully the areas you've already scrapped still have some copper cladding left on the PCB. Dry completely.

Whatever non-corroded good traces that are left will be a dull gray (solder covered). You should "jumper" over the green, corroded portions (as suggested by Diver) with a small, insulated wire that is soldered to the good (gray) section(s).

Also check for corrosion on the underside of the battery holders.

If, however, any of the green traces disappear beneath the black "glob" (the IC - the LED's flashing timer) with NO copper visible after cleaning, then the unit is toast.

 

[throbscottle]

You can get "pens" for cleaning corrosion, which have a glass fibre refill. One of these would be your friend.