Amiga 500+ questions

[Viserion]

Got my self another of these MBs and as usual there is some battery leakage.

I have brushed it with IPA, and used white vinegar to neutralized the acid. I have also read that others use lime instead.

Is one better than the other?

As I really want to do a proper job, when I have started the repair job.

I also need to take off 1 or 2 IC, and I notice that in an area of the MB close to the battery there are numerous solder points that are dark grey instead of the dull silver colour the others are.

Is there any point to remove the old solder, and add new solder instead.

If yes, how to you get rid of the dark grey coating, so you can remove the old.

[pandy71]

IMHO vinegar is more aggressive, side to this all acid need to be clean with water well to prevent corrosion.

Old solder can be removed by soldering suction pump and/or by desoldering braid.
Use some non aggressive 'no clean flux', don't use RoHS solder.

[Viserion]

So I should go over to the lime/citrus instead then.

I have cleaned this with IPA and a tooth brush, not wanting to use water as it usually is not a good mix with electronics.


The reason I asked is that the dark grey seems to isolate solder so it doesn't melt. I am afraid to use more heat as that could destroy something.

[Total Eclipse]

When I removed the battery from my 500+ I used vinegar and a tooth brush, immediately followed by a rinse with distilled water and an hour in the oven at ~60 degrees.

[ajk]

@Viserion

The dull solder can be tricky to melt with just the iron, but add some flux (or new solder, which contains flux) and it should be much easier.

[Viserion]

TotalEclipse: Don't have distilled water, so will have to get some unless you can use tap water instead, but then it's possible to have residue of the tap water.

Will see what I find, or else I will use IPA to remove any residue.

ajk: Thanks for the tips. Will continue on my A500+ shortly.

[Viserion]

I found an old bottle with distilled water, and did as Total Eclipse suggested.

Don't know if it was a success or not yet, but it looks dry.

Plan on solder on the components tomorrow, in addition to remove the grey solder.

[pandy71]

Originally Posted by Viserion

I found an old bottle with distilled water, and did as Total Eclipse suggested.

Don't know if it was a success or not yet, but it looks dry.

Plan on solder on the components tomorrow, in addition to remove the grey solder.

Demineralized water is used for ironing - should be available in any grocery, correct steps should be:

Unsolder (cut off old battery),
clean deposits, you may use citric acid or vinegar
rinse well with regular tap water
rinse well with demineralized water
use IPA to remove remains and to dry water (water with alcohol create mixture that vaporize good as regular alcohol)
dry troughly (1 - 2 days) in warm places
Most important is to dry areas under SMD mounted IC's

[Viserion]

Too late to follow that exactly, as I have already done the oven trick.

I have used a tooth brush to clean it with IPA, and said water.

As I took out all removable ICs before putting it in the owen.

It looks dry, but depending on how much soldering I get to do today, I probably won't power it up before tomorrow anyway.

[Viserion]

Most of the work is done, but there are some solder points that won't take solder.

At least on the top side. They will on the bottom side though.

It's only the ones that where the most attacked by the acid of the battery.

I am a bit concerned that the solder on the underside will be too thin, as ther is a very thin layer that will hold on some of the solder points.

[roy bates]

the only other way would be to remove all the parts in the effected area including the sockets,gently flat down the top with wet a dry paper in water or abrasive powder to remove the lacquer to expose the traces after removing all the parts and remove all the solder from the vias and re do it again then maybe add a lacquer coat after the parts are fitted again.

you might have to pre heat the board to help do the ground plains in alot of the vias.
and /or lots of flux paste.
sometimes adding more solder with flux paste helps remove stubborn solder from joints on its own.

it wont hurt to look under sockets and ic's in effected areas,you can find broken traces under them easier.

its just my opinion though.

ive seen battery leakage reach to the cpu socket on these,although that machine was probably stored on its side.

[Viserion]

In this case it is some of the solder points between U12 and U13, and a few above U12, that is the problem.


The rest looks good.

As the holes are tiny, I'm afraid to to more damage to traces.

Hav eto see if I can find a way to do it that deasn't destroy anything else.

[Viserion]

Done a bit more cleaning, and I'm pretty certain that the metal rings(for lack of better word) is either gone or disintegrated.

Particularly in one of the holes I can't get solder to stick on either side of the board.

On 3-4 others, I can't get solder to stick on the top.

I tried searching for the metal rings, but don't really know the name for it.

Is it possible to get replacements for this, and what are they called.

The holes are very small, so I'm uncertain if it's even possible.

I do have some electric conductive paint, I thought to use as a last resort by using that instead of solder.

Would that be a solution instead?

[kipper2k]

Originally Posted by Viserion

Done a bit more cleaning, and I'm pretty certain that the metal rings(for lack of better word) is either gone or disintegrated.

Particularly in one of the holes I can't get solder to stick on either side of the board.

On 3-4 others, I can't get solder to stick on the top.

I tried searching for the metal rings, but don't really know the name for it.

Is it possible to get replacements for this, and what are they called.

The holes are very small, so I'm uncertain if it's even possible.

I do have some electric conductive paint, I thought to use as a last resort by using that instead of solder.

Would that be a solution instead?

If the holes(vias) are rotted out then you have no choice but to start running jumper wires from known good points to further along the trac at another junction point. It is possible to feed thin wires through a good via so you have that option. Don't bother with conductive paint, its expensive and too much hassle for a board with a lot of bad tracks.

Take hi-res pictures of the board and start looking at traces that need to be jumped if you are willing to do the work. It's an A500+ so i would try to get it working if i were you, especially for the benefit of more chipmem etc.

Think of the repair as playing a game and see if you can get to the end

if you need some hi res of a certain area, ask me... i have lots on the a500+.. with and without sockets

[prowler]

Those metal rings are called solder pads (or just pads for short).

It is possible to buy PCB repair kits from hobby electronics suppliers (such as RS Components and Maplin in the UK), which consist of sticky-backed copper tracks and pads you can use to replace those which have been eroded by battery leakage.

Edit: and/or just follow kipper2k's troubleshooting advice above.

[Viserion]

I already have the electric paint already, and have opened it, and as I must use it within 6 months of opening it anyway so might as well use it if it works, as I never be able to use all of it by that time anyway.

The tracks themselves look good, but will upload a picture tomorrow, as it already way past my bed time.

By the way it is an A500+ , so I do this both to get a fully working board(I have one that works with an ACA500 only, and several that won't boot), and to get some knowledge.

I don't mind the wires if it comes to that, as I'm more interested in the functionality than someone with more aesthetic sense than me .


Oh, I forgot. I will also check out the repair kits, to see if they are worth it or not.

[pandy71]

Paint is not OK - is unreliable , may be to high resistance and fail after hard to predict time.
In case where PCB is damage apply "point to point" method - localize signal (use schematics and multimeter - in ohm or continuity mode), check where signals ends, connect both points directly, try to recreate shape of trace with insulated wire, there is special wire in usually PVDF/PTFE insulation so called kynar wire - this is correct, industry like approach to fix corrupted PCB.

[Viserion]

Okay, then I need to get some of those wires first.

[Viserion]

Here is a few pictures that I said I would upload yesterday.

It's the second from the top on the left side of the label battery, that won't hold solder from neither the top or bottom side of the MB.

The rest have solder on the bottom side.

[pandy71]

Originally Posted by Viserion

Here is a few pictures that I said I would upload yesterday.

It's the second from the top on the left side of the label battery, that won't hold solder from neither the top or bottom side of the MB.

The rest have solder on the bottom side.

this may help you a bit

http://uk.farnell.com/duratool/d0226...4mm/dp/2102028

Some vias may be damaged (not sure how many layers is on A500+) if there is more than 2 layers then wire may be only one way to fix PCB/