Amiga motherboard (A3000) cleanup with Isopropyl alcohol: weird results

[da9000]

Hey guys,

following a lot of the suggestions on the forum about cleaning a battery spill with Isopropyl alcohol, I decided to be a bit more aggresive (in the past I cleaned the regions attacked by the spilled battery contents, acid in crystalized form, as far as I can tell, but it didn't do any good, my A3000 was still dead and showing a green screen. I replaced the soldered Chip RAM with sockets, but still no go).

So I poured copious amounts of isopropyl on the various 'infected' areas and then let it sit for a few minutes, then took the board and shook it to take the large amounts of alcohol off, and then used a blow drier (in cold-air mode) and had it blow on the board for a few hours to dry it out. Anyways, the most weird (to me) thing happened: there's various sediments, white in color, over various pins, both on the upper side of the board, but especially visible on the underside of the board, even in places where I wouldn't think the acid has crept to (Chip RAM area).

Has anyone seen this before? Is it what's left after the alcohol reacted (if it did) with the acid or acidic crystals? Could it be something else? According to some searching results isopropyl + sulfuric acid = propylene gas, but I doubt NiCD batteries contain sulfuric acid, as the name suggest Nickel and Cadmium.

I tried adding images in the Hardware section, but they don't seem to appear  Let's try here... OK, can't do it either The 'image manager' button doesn't really draw properly, and neither does it have a way to load a photo. Can someone help with photos/images ?


Observations:

1) it comes off easily with an old toothbrush
2) it seems to be like fine dust, like a white salt (not the kind you put in your food)
3) it's almost always around pins (or rather where pins stick out from the bottom of the motherboard), but also (less often) around pins going into the motherboard, from the top side

UPDATE:
Photo 1:


And a link:
http://www.amiga.org/gallery/index.php?n=1821=11

[da9000]

@Amiga_3k:

Ok thanks, I wasn't aware about the delay on the photos. I will wait and edit the previous post. Ok, I just checked: only 1 made it up Here it is anyways:
http://www.amiga.org/gallery/index.php?n=1821=11

As for the repair, yes, I'm very aware about the traces. Unfortunately I can't find any bad ones, and even though some people have suggested that since it's a multi-layered board there might be internal damage, I really believe it's not the case, because as I was looking at the board, under a very bright light, I can only see a middle layer(s) under the SMD 68030 CPU itself. The rest of the board does not seem to use the middle layer(s). Especially where the battery was, there doesn't seem to be any via ducts underneath. I'll keep on looking of course...

@Framiga:
Yes, thanks, Castellan's site has been my guide all along! He rules! Anyways, I'm not replacing a new battery yet (old has long been removed), because the machine boots to a green screen, so first I have to fix it, then I will add a new battery (probably lithium battery hack or a large coin-capacitor which I bought from www.jameco.com)

@KThunder:
Yes my custom chips are intact. In fact I tried as many as I could (anything that would fit in an A500) and they all worked great! In fact better than the A500's chips! (8372A Agnus would cause "screen trash" while moving windows, while the A3000's 8372B didn't!)
As for centisoft, I don't know... 97% rating and people leaving negative comments, and also last time I contacted him he was kinda avoiding the questions (about shipping for example), so even though it's cheap, I'm afraid I'll end up with 3 more DOA boards, to make a grand total of 4 boards and zero working A3000's ... (EDIT: his auction SEEMs to suggest that you get 3 motherboard, looking at the photo at least, but you only get 1. Centisoft = scumbag )

Maybe I should go check the "vendors" list you guys have been compiling...

[da9000]

Hehehe, yeah, it looks like a real mess, doesn't it?

The photo quality sucks, sorry but I don't have my digicam with me right now  Anyways this white stuff comes off very easily with a toothbrush... so I'm hoping (and thinking) that it cleaned up anything left over by the battery really well, and pushed it out of the various nooks and crannies.

As for drying out, I don't know how quickly it dried, but I just set the blow drier and let it go, did some other stuff and then got back to it. So maybe not hours, but one hour? Perhaps it dried really quickly, I don't know :/

[da9000]

Jeff wrote:
I try to avoid comments about specific sellers after taking some heat from "a rude guy in Canada" however I did buy one of those untested A3000 motherboards on ebay you are probably looking at.

It is complete junk, infact you can have mine for the price of packing and shipping if you really want it, I don't:-). It is an early revision unfinished board with TONS of solder work already done, ports missing and damaged, chips missing, ect. To top it off it looks like it was sitting in a stack of 50 or so and then someone played frisby with it.

Thank you Jeff!!!!!!!!! That's what I was afraid of!!!!!
Did you buy it from the Centisoft guy? He says he send 3 at a time for $10... but if they are like you said, then what good are they, right?

I'm being patient and calculative. As much as I can. I'm also stubborn so I won't give up easily on trying to fix it. I'm not a newbie with fixing things, although I suck at electronics, but with all the great help from all the Amiga gurus here and some friends of mine, I'm hoping one day I'll figure out the bugger. I really don't think it's anything that serious as the damage was "contained". I just can't SEE it yet...

As for cleaning, I just used a toothbrush and the white residue went away easily enough

[da9000]

ral-clan wrote:
While alcohol is certainly recommended for cleaning electronics (it's fairly benign), it shouldn't take as long as the stuff you had to dry.  Sounds like yours had a lot of water content in it (or you just dumped on a ton).

But I also read somewhere that washing battery acid damage with VINEGAR is a good idea, as it would neutralize any remain acid activity in the residue on the board.

I'm not sure how this would work....wouldn't you need a base to neutralize an acid?  Is the stuff coming out of a burst battery an acid or a base?  White vinegar is an acid (acetic acid).

The one I used was typical super-market stuff: 70% isopropyl. As for drying time, I didn't wait for it to dry, I just let it dry, so the fact that it dried after an hour doesn't meant it didn't dry before I didn't time it. I'm sure it dried quickly enough.

As for vinegar, I read that in the past and have used it (successfully = no visible harm done), BUT in these forums some of the expert electronics guys advised against using vinegar or baking power, and only using isopropyl. So I'm sticking with isopropyl. It also doesn't smell foul like plain vinegar

Note: when I tried vinegar on the "furry" stuff coming out of batteries (in the past), I could hear it "sizzle" or "fizzle" (?) as it was reacting (I'm guessing) with the crystals. I felt like it was doing its job, but that's just a guess on my part. Perhaps it was eating away at my motherboard more quickly?!? (this was on another machine)

[da9000]

Framiga wrote:
sorry but a "The one I used was typical super-market stuff: 70% isopropyl." is out of the game for cleaning electronic stuf!

=>99% is the right number! :-)

Couldn't find any How is it going to be different?

[da9000]

Wol wrote:
da9000

Looks like a Lead compound to me, possibly
some form of lead sulfide or oxide or nitrate.

It will have formed due to chemical reactions with
the battery electorlyte and or the Isopropyl.
just remove it with a Nylon brush eg: Nail brush or
hard toothbrush.


Wol.

I have no idea what it is, but you seem to know better I took it off with exactly that: hard toothbrush
No improvement in my A3000 But that's probably because some trace is broken somewhere or something...

What was interesting is how the white stuff appeared around various pins/holes... as if there was acid inside the motherboard and the alcohol got in there, reacted and pushed the stuff out. I doubt that's the case, as the battery leak was cleaned almost immediately (about 5-6 years ago), but I was a neophyte then so I think I only used some Q-tips with plain water, and not isopropyl. After having sat unused for 5-6 years, it seems the acid kept on eating away at places. I _believe_ it booted one last time (after the 5-6 year hiatus), and then it just started green-screening ever since :~(  ...My first 'migy ...

[da9000]

Framiga wrote:
"Couldn't find any How is it going to be different?"

a 30% of "only Jesus knows" remaining stuff!

Anyway... i can provide a RS-Components RoHS IPA 400ml can code ID

cod: 693-775

but not knowing where you are from, i don't know if it could help.

Heh... If you insist that 30% more pure is better, I'll look for it. I'm in the US so I don't know if I can find that specific one, but I know some electronics shops, so I'll see what they have. Thanks

[da9000]

Framiga wrote:
the problem now is not the quality of the alchool anymore.

Now you have to find anf fix the damaged parts. Look at the damaged zone with a magnifier lens (or what you prefer)

I would suggest you to reflow the solders also (obviously if you have the right tools)

Yes, I've been looking as hard as I can, but tomorrow I will add a high-quality camera with a monitor so I can get even closer and more detail on the board.

I'm not sure if sure if "reflow" means to use one of those "heat guns", but I've re-soldered a lot of the pins/joints on key components around the damaged area: all Agnus, Denise and Paula pins, and some other ICs and components around them. This was all done from the back side of the motherboard. I've also replaced all the soldered Chip RAM (1MB) with sockets and put new (and tested) DIPs. No difference  I've also tested all diodes (zener and not) by removing from the motherboard. Also tested all fuses and they are good. I don't know how to test caps, inductors, ferrite beads and that "EMI" stuff... I also tested all resistors _without_ disconnecting them, and none seemed to be shorted (didn't test exact values to be honest).

I've started looking at the schematics, but there are too many lines and I'm getting confused
My next plan (as far as testing) is to find out how to test certain chips that are related to the Chip RAM (since I get a green screen, and then a black screen after a couple of seconds, and immediately a green screen again), so I can see if they are getting the right voltages at least. I don't have a scope so I can't test to see if they are also getting the right signals :/

Wish me more luck!

[da9000]

amiga92570 wrote:
Use a commercial board cleaner available from an...

I will try to get some. Any suggestion for places/stores/brands?

I don't know if my solder is "acid core". How do I find out?

I've tested all suspicious looking tracks and they seem ok with continuity testing. Any suggestions at which points I should be testing voltages at? And how can I test the oscillators (I don't have replacements) ? Finally when you say "verify data, address, etc line", are you talking about the ECS chips or the Chip RAM itself?

Thanks

[da9000]

Just wanted to say thanks for all the input guys. I'm going to get some sleep now... been up all night trying to figure this thing out. I'll update this thread as I discover new things.

In the mean time, can someone who's a hardware expert tell us a bit more about the multi-layerd Amiga boards? After looking at the A3000 rev. 9 board with a bright light, at an angle, I could see the middle layers ONLY under the CPU area. Nowhere else. So, if the area under the battery was corroded (as it is in my case), do you really think it has affected something under there that's important? Or not? (from what I can see there's nothing under the battery section)

Thanks in advance!

[da9000]

@amiga_3k:
You're correct in that if the solder job is not well done, the alcohol or other liquids might sip through. But what I think happened was that the alcohol didn't sip through to the other side, but because I put so much of it, it just overflowed and went around the board (the board wasn't horizontal the whole time). My solder job is pretty good too, so I had made sure there were no holes or anything of the sort. Of course I can't be 100% sure on that, but I think it's ok (based on other jobs I've done). But right now I can't take that stuff apart, because I have no more solder wick, and it was such a pain in the butt taking the Chip RAM out, to begin with. But even when I took the Chip RAM out, I didn't find ANY bad chips. So the problem was not the Chip RAM. It's someplace else...
Thanks for the idea though


@Framiga:
Yes, I've done a little 'via testing' but not much, because it's hard to get the board to stand up... I'm not a pro, and I don't have the right equipment. But yes, the problem is definitely with the motherboard or the chips I could not test, but I don't think it's the chips because the computer was working solidly. It's the battery the killed it, I'm 99.9999% certain.
"Multo grazzie", I'll need lots of luck!


@Castellen: (<-- this guy is my hero! without him or his site my A4000 would be dead or trashed by now!)
I'll take a paragraph approach on this one:


History:
--------
I believe the problem is due to the leak, as might be evident from the history so far: the machine worked fine for a decade almost. Around 2000 I noticed the battery get fuzzy, but no real spillage. No scars, no corrosion on the mobo. Removed it, cleaned the area with, I believe, wet with water Q-tips and the like. I don't think I used any sort of alcohol, but it's been too long to remember. Left it sitting until 2005 (I know... now I'm paying for it). Turned it on around May 2005, and I _believe_ it booted to some sorta ok state (Kickstart screen or even WorkBench, I forget). Turned it off and then on again and it green screened. As soon as I saw that, I opened it up again and saw that inside it had a few nasty scars, not only where the battery was, but specs of scars around the surrounding area. But they were small scars, like it had drizzled acid. No big scars or corrosion, except where battery negative terminal was. Also, no corroded ICs or sockets, or pins. Just a bit of green/blue (tirquise?) on some pins, like the resistor and cap north of the negative terminal and a couple of the ICs near there (U480, U477, U472).


Typical things:
---------------
I did reseating of all these ICs: 2xCIA, SCSI, Agnus, Paula, Denise, Chip RAM, Kickstarts (2.04), RTC, 4xGAL chips on the Chip RAM side, disabled FPU, removed all Fast RAM for now. Maybe I should do _all_ socketed ICs like Amber, Gary, Ramsey etc? Would any of the ones I didn't reseat cause a green screen? (I don't know which other chips access Chip RAM). I also tested the following on my A500: 2xCIA, Agnus, Paula, Denise. All worked flawlessly.

[EDIT: I resat all socketed chips. I read someplace that Gary could possibly cause green screen].

Socket repair:
--------------
I will use your method, but I prefer to use sockets, so I will go buy some good ones (machine pinned as you said), and remove the existing and stick the new ones in. And yes, the ground/VCC pins sucked big time because of the 'heatsink' effect. Especially when trying to remove the Chip RAM. But for informational reasons: I did re-heat/re-solder (what's the right term?) the actual socket joints for many of the ICs in the area (Agnus, Paula, Denise, part of the video circuitry, RTC and a couple of the surrounding chips). Nothing changed


Advanced terms:
---------------

It's near impossible to create a "bad" solder joint with plated through hole technology. Usually the worst thing you can do is have solder shorts, but you've got to be pretty bad to do that with component technology this big!

This went a bit over my head Can you explain the "plated through hole tech" ? And as for "solder shorts", do you mean because the holes are too close? I've been very careful, testing with my DMM to make sure there are no shorts.

[EDIT: I understand now, and I agree 100%]

Isopropyl:
----------
Yes it looks a bit worse than expected, and at some point I thought it might have to do with the soldering job. I'm not so sure because of one thing: the Chip RAM I desoldered were the last 2 banks, 8 chips. The farthestmost bank (4 chips, 0-512KB) did not have any of the white gunk left afterwards. But the 2nd from farthest bank (4 chips, high 512-1024KB) had tons of it! And it's not like I did anything special when desoldering/soldering the 2nd set... Also of note: the next 2 banks (1024KB-2048KB) didn't have any gunk. Of course these were soldered from the factory and I didn't really touch them.

As for the purity, I agree with ya: I'll keep the high quality stuff for my meth experiments and use the 70% for 17 year old motherboards And the damn alcohol is so expensive for such a common "ancient-tech" thing...


PCB layers:
-----------
Thanks for the "lonely vias" tip! That is really really helpful, so now I can track and see if there is any inner-layer usage near the scars! And yes, of course I've been using your "via repair" page to guide me along this Herculean task

Thanks again for all the info/tips/help Castellen!


I think Wayne's server drives must be chocking right about now!

[da9000]

Just an update:

I checked the A3000 power supply, just to be certain, and I got the following readings. In general they were pretty stable, only the 2nd decimal digit (0.0x) changing once in a while.

Pin  Voltage
---  -------
1    +4.92v
2-6  +5.12v
11   -4.92v
12   +4.93v
14   -11.90v
15   +11.72v

Pins referenced from: http://pinouts.ru/Power/amiga3000power_pinout.shtml

BUT while measuring voltages on the motherboard I found something suspicious. _Most_ (I didn't test all) of the ICs on the Agnus side of the board were getting 5.02v to VCC, except U452 and U451. Those two were getting 4.76v. Could this be a problem?

Another general question: would an A3000 work with 1x256Kbit chips for Chip RAM? Or must it have 4x256Kbit chips? I'm just curious, but I've been using 424258 NECs (details here: http://www.amiga-stuff.com/hardware/256kx4-dram.html), which were there to begin with...

[da9000]

Castellen wrote:
You could probably still get reliable soldered joints from a blind gorilla weilding a flame thrower.

Actually, I've just been working on some boards which appear to have been soldered by such a beast, but that's another story...

LOL!!!!!  :roflmao:

I wanted to just update the thread about the whole "battery acid" thing. It's not acid. Zac67 is right:

http://www.amiga.org/forums/showthread.php?t=30657

Doh! You're completely right - the caustic stuff in a NiCd battery is NiOH, obviously a base and no acid. Old "zinc-carbon" batteries use ammonium chloride, which is an acid.

There's always something left to learn...

Further update on my case:
Nothing exciting. All chips seem to be fine, except my Agnus. It seems fried. I also spotted some problems with my soldering on the Chip RAM, but those are fixed. Perhaps there are more, or the problem remains elsewhere

[da9000]

@amiga92570:

I've cleaned the board up some time ago. I had a couple of questions for your previous (top of page) suggestions:

1) I don't know if my solder is "acid core". It says "Rosin-Core, Silver-Bearing Solder". I guess that's not "acid core", is it?

2) I've tested all suspicious looking tracks and they seem ok with continuity testing. Any suggestions at which points I should be testing voltages at?

3) And how can I test the oscillators (I don't have replacements)?

4) Finally when you say "verify data, address, etc line", are you talking about the ECS chips or the Chip RAM itself?

Thanks!