The Three Stooges, I mean Bezerks. Blowing life into them again....

[level42]

Just found the answer. Battery leakage is actually no acid at all.
It's a (alkali) base !

So, we do the right thing and fight it with an acid (vinegar).

I've asked a question on KLOV if we should mix it with water before using it and if we need to use demineralised water to rinse after the process. Until now, I get some stuff that looks like chalk around the legs of the parts, and I don't really like that....

[polaris]

lol andre i was just about to ask is the battery acid or alkaline, i think there are both.
ok
the equation
base + acid = salt + water, the residue is the salt in the equation
the salt should be chemically inactive so just needs to be washed off, cant harm to use demineralised water
what acid is it you are using andre?


EDIT oops removed the gaps for andre

[petieken]

When I see suspicious or stubborn substances on a pcb (non-battery leakage stuff) I always try to remove it first by dipping a small paintbrush (like the kids use) in alcohol and swipe over the area.

Lately I found out alcohol is effient for more things than just drinking it

[polaris]

unconfirmed information following
just been reading that it may be potassium hydroxide in the battery which is a very strong base so may need lots of acid to neutralise it.
bear with me andre i'll see if i can make sense of the chemistry

[level42]

Right, Ully's ZPU has been running 100% stable ever since I started it earlier this evening after the 2nd bridged track.

I officially declare it repaired now. Acid and battery tomorrow....

[level42]

what acid is it you are using andre?

This is exactly the bottle I've got here:

http://www.schoonmaakazijn.nl/

(The green one, the others have added scents, which we don't need).

The site says that vinegar is the weakest acid. Also: "Schoonmaakazijn" (= "cleaning vinegar") is only used for cleaning and not for food preparation. If mixed with water too much the cleaning function will be lost (so I guess we really don't need to mix it for our purpose).

It also says: Cleaning vinegar has an acid percentage of 8% which is a lot higher then that of "nature" vinegar that is used to prepare food.

The rest of the site gives a lot of uses for this stuff. F.I. fighting cat-piss stains (!) and fighting chalk rests....but also cleaning a dishwasher etc.

[level42]

So, I gave it a bath yesterday. We really needed to stop the base residue from further eating tracks and parts......

Something I noticed: Most PCBs are (screen) printed with (white) texts to identify partnrs. on the PCB. This is easy for repair. Stern did it's very best and even "drew boxes" to indicate what function each area of components has.

Nice, but I scraped of a little bit of the white line at one part, and discovered the copper track under it was fully covered with the bad-blue base battery leakage! I guess those lines are like a "border" or a "dam"....it holds (and keeps) the leaking stuff on the same place and thus let it have even more effect....

Anyway, after vinegar, scrapping bad looking areas (tracks) and more vinegar and of coure rinsing and drying...I tried the board this morning and now it's completely dead. No beeps just a steady LED.... 

Must have scraped off a bit too much somewhere......arrgghhh, o well, will look into it tonight. It can't be a big problem.....

[level42]

.....and fixed ! 

I was pretty puzzled by this one. I scraped carefully and all tracks looked OK.

A tip: use a very bright light (f.i. halogene or TL) light and shine from the back of the PCB and try to look "through" it. This really helps to follow tracks and sometimes (not always !) you can see breaks.

It all looked OK. I measured all the tracks where I had scraped the cover from and they all beeped out just fine.....mmm weird.

SO I started checking for shorts between the + and - supplies and ground but it looked ok.
Then I thought about measuring the reset button. If this would constantly short, of course the board will never boot.
So I measured it and got some readings of resistance. Normally you don't get that at a switch of course, it's either fully shorted or fully open. So I desoldered the reset button and tested and it's been running fine again now for about 30 minutes. I'll "transplant" one of the reset buttons from the other boards (of course I will check it first).

I actually think that the rinsing was causing the problem this time. There may very well still be water inside that button. It worked fine before. It can also be that the button was already dodgy and the water gave it it's last push, but I doubt it.

Another reason why I tend to not wash PCBs if not strictly necessary, like now.

[level42]

Battery installed. Had to jumper another track (!) to get the diode properly working.

She's not a looker anymore with all those bridges, bare copper etc. but it works great now. Saves scores, no re-booting.
Will keep it in my machine until I go visit Ully, that's the best way to test it thoroughly

[level42]

After three days, still going strong !

(Why do I have the feeling I keep talking to myself in this thread ?  )

[petieken]

Keep posting the progress! I've been reading these repair logs from the beginning with interest .

[polaris]

you know i read them i just barely understand them, so i only post very occasionaly

[Superully]

(Why do I have the feeling I keep talking to myself in this thread ?  )

it might SEEM you're talking to yourself, andré, but i'm sure a lot of people are reading along - myself included. it's just that i'm so nervous about these berzerk boards and their tendency to fail ...

[Etienne MacGyver]

(Why do I have the feeling I keep talking to myself in this thread ?   )

I know that i am following every step of the way !

there is only not so much to give comentary, i can only say that you are doing a wonderfull job puzzeling this out everytime there is a failure, wich i really like, and its learnfull stuff.

I know some basics, but its interesting to folow, and usefull to me in some ways,

Keep posting the progress please !

[DarthNuno]

I know that i am following every step of the way !
there is only not so much to give commentary, i can only say that you are doing a wonderful job...

+1