View Full Version : what to do about 386-486 system preservation

November 28th, 2008, 06:10 AM
Anyone have experience cleaning up battery leakage, or should I just trash any system with battery problems? I dread the task of opening everything up that *could* have leaked, but I guess I have to do this asap. I have put aside a lot of 85-95 computers when I get them, they're not really in my area of interest, but at the same time I want to preserve them. I have 15 or so 386-486 systems, probably have 20+ bare motherboards from the e386-486 era, Amiga stuff, etc. All of this I have more or less ignored as "not vintage" - Maybe this is a mistake - whatever you call computers built before the WWW age and after 1985.

Would a basic solution (vs. acidic) and a needle pick do the trick? I have seen some threads on the subject in the board and I will do some more research.

50 years from now working 386 machines are going to be harder to find than 8088's should all of the MB batteries leak. In addition to a battery problem that no one want to "touch", people don't consider 386-486+ systems vintage so they have gone unattended. If you're like me, I'll accept a lot of computers from a donor, but they insist I take "everything" and that's how I have accumulated these newer systems.

Anyone here specialize in the 386-486 as a collector here? I use a Compaq Deskpro 386s with 5 1/4" and 3.5 drives as my bridge system for copying disks and files. The Deskpro has a detached battery.

Despite their external appearance, the 1985-95 era machines require the most attention, at least of what I have. For purists here I will call them "GUI-era vintage" so as not to confuse them with traditional vintage computers. Whatever you call them they need to be preserved NOW.

I have posted some pictures of 386-486 boards I have accumulated over the past 10 years. Here is a link to my items available page, which includes a lot of these items



November 28th, 2008, 08:23 AM
All of the 386 Mobos I own have off-board 4-AA size battery holders supplying the clock. They're in no danger of dying due to battery leakage, although the case might suffer a bit. Many were purchased that way; others had external batter connectors on them and an option to leave the coin cell out.

I'm more concerned with systems using the Dallas Semi internal-battery clock chips. While one can cut into the epoxy and find the battery, it's not an elegant solution and replacements can be very hard to come by.

November 28th, 2008, 09:04 AM
I stockpile almost any 386/486 board or processor I find. In most cases though I have found that the local computer shops didn't use soldered-in batteries. I see quite a few boards where they used either a CR2032 or some other off-the-board battery.

November 28th, 2008, 10:36 AM
I usually just use a paste of baking soda and water to neutralize any acid that might be still around ( I believe the green crystals are cupric sulfate ) then wipe if off with a wet rag.

Then I use a pair of small diagonal cutters to clip the leads on the NiCad barrel and do the area under it.

A brass-bristle brush will clean up any other residue.

If any of the traces are eaten through, a piece of wirewrap (stripped) soldered across it (or a little piece of the lead off a capacitor or resistor for power or ground traces) will take care of that.

November 28th, 2008, 11:15 AM
I pretty much remove the dead batteries as soon as I get the motherboards (very few have any charge left, and only a few seem to have leaked already). If they do leak the area affected is probably just the keyboard port, or in some cases the memory slots are close by. The Amigas seems to put the batteries close to important things like the processor and have been known to kill boards.

Mostly I just clean up the small leaks with alcohol since the board coating keeps the junk out of the traces unless it has been leaking a very long time.

External batteries are fine for when you need to setup and use the systems, but if you are just using a few AA batteries in a case remove them when not in use or they will leak as well.

November 28th, 2008, 01:24 PM
Hi Gang !

I too collect old motherboards. A couple of years ago ( to make a long story short ), I had found a very important computer ruined because the battery pack ( 3 AAA batteries ) leaked and ruined the MB, case, PSU, etc.

I then went through my entire collection of 286, 386, and 486 boards, and anything that even came close to looking like it was leaking was "removed". Naturally, I had quite a few boards that were already beyond repair.

You are correct, be dilligent, and go through those computers before it's too late.


November 28th, 2008, 02:05 PM
What to use to clean up the damage depends on the type of cell used. If the cell was an alkaline or lithium, then a solution of white vinegar works well. If it was a carbon-zinc primary cell that leaked, use a paste of baking soda and water.

Almost nothing in my experience is harder on a PCB than old cat urine. It eats right through the resist and completely dissolves the copper traces.

You don't want to know how I discovered that one.

November 28th, 2008, 03:00 PM
Thanks for the replies. I am glad to hear that the boards are not beyond hope if there has been a leak.

Today I checked my Apple IIGS - The battery is dead but not yet leaking.

I am going to use baking soda and water to clean the effected areas of boards that do have problems, clip out the batteries, and in their place solder a wire to a detached battery holder.

I have been told that this acid is caustic, wash hands after touching/avoid touching.


Terry Yager
November 28th, 2008, 10:36 PM
Am I the only one who uses H2O2? (The cheap kind, from the Dollar Store), and a toothbrush-size soft brass wire brush (for people with really heavy plaque buildup). Works for me...sometimes. Be sure to rinse with H2O and dry thoroughly before testing (use yer wife's blow-dryer).

Of course, success depends on the extent of the damage, YMMV.


Terry Yager
November 28th, 2008, 10:39 PM
I have been told that this acid is caustic, wash hands after touching/avoid touching.


Vs the non-caustic type of acid...???