Hxc on DDI-1 ?

[SyX]

Well, even if it's an ST, poooor st 

[Bryce]

Just checked back through my files. It was in fact an Amiga. The battery was no longer functional but not leaking, the entire PCB had this type of corrosion, not just this area.

Bryce.

[MaV]

Just checked back through my files. It was in fact an Amiga. The battery was no longer functional but not leaking, the entire PCB had this type of corrosion, not just this area.

Bryce.

How could this have happened? The battery must have virtually exploded.

Oh, you edited your previous post. Sea salt.

SyX, you're right. Poor, poor Amiga.

[Zetr0]

I wrote up the following on www.amibay.com, to help some fellow AmiBayers understand the battery leaking problem that is inherent of these wonderful machines.

Now before I splatter some text here, Bryce is most correct to warn everyone about the dangers of sodium hydroxide, this is very prevailent in coastal area's.  I have seen area's even in the UK strip a cars outer paint within a month (although that is great Yarmouth so I wouldn't put that past the kids out there either lol)

I would humbly suggest that unless you use a proper rinsing proceedure of electronic equipment once from the dishwasher, not to use it,  like all tools, you must know the best way to use it as it is important to know that any cleaning will probably use an agent with water, obviously for those that know we use (a lot of) isopropyl alcohol (IPA).  It is the best way to clean any electronic device (alternatively you could use car screen wash which is diluted IPA, ensure that you dont get one with a ton of strange detergents in it! or any if you can find it)

Now that bits over, heres the science bit -  I tried to keep the following far from A level chemistry as possible without going into full mind-numbing and tounge swallowing reaction equations.

There would be better ways to say this but this is the laymen expression, if anyone feels a better expression or more detail is require please add to or post on =D

It is a bit winded this post so jump to the end of it to catch the highlights.



Still here?  then Lets Begin =)


Whats in the NiCad Battery?

The rechargable battery like that on the A500+ and the Amiga A2000 - are officially called a NiCad (Nickle Cadmium) Accumilator.

A NiCad Battery consists of nickel oxide hydroxide, and metallic cadmium as electrodes - this is then emersed in (potassium hydroxide [KOH]) an alkaline electrolyte.


When it leaks: Reaction Time

Initially what happens is the reaction process here starts off with with the battery leak - this causes the Potassium Hydroxide to react with the air.... this over a time and room temperature will create Potassium Perxoide. Both of these chemicals react quite strongly with Copper.

Peroxide is a VERY strong oxidizer, when you have this combined with Copper (an oxidizing metal) you have a very compound problem, as you can imagine what starts off small will cresendo to a larger problem in a short space of time.

Environmental factors do play a part in this, from temperature to air humidity - all effect this copper - potassium hydroxide / peroxide reaction.

Now potasium peroxide is an inorganic compound with the molecular formula K2O2, it is also a mild alkaline to a base pending on its strength.


How do we fix it?

To neutralize an alkaline we must use an acid: of course acid will also react with Copper, infact theres very few things copper wont react with, so we need something safe and controllable - Acetic acid (i.e. spirit vinigar or natural lemon juice) - although this would react with copper - its relatively insignificant when compared to the peroxide base that has built up in concentrations on the PCB.

The acetic acid neutralizes the base and provides an alternative for oxidization with the peroxide being that its an organic compount.  As a plus point it also breaks down the concentrated Copper Hydroxide (those blue/green fuzzy bunnies) left over from previous reactions.


But why?!?!?

Copper Hydroxide is mildly amphoteric, This is the double whammy for the copper tracks as the more that reacts the more alkaine is produced thus the more it reacts untill it runs out of oxygen/copper..

There are four driving factors for this reaction

1. The amount of potassium hydroxid that leaks
2. The amount of potassium hydroxide that reacts to form potassium peroxide
3. The air humidity
4. The temperature of the PCB and environment.

I could go on with the forming of cystal and copper dendrites and electrical impedence - but thats only going to bore the pants off every one lol


In short (for those that skipped)

1. A NiCad battery has an alkaline electrolyte.
2. Electrolyte leaks and reacts with air to form a strong oxidizer
3. Copper is an verilent Oxidizing metal
4. Electrolye is an Alkaline and will concentrate to a Base
5. Copper reacts with Oxidizer causing more Alkaline
6. Alkaline reacts with Copper and Air creating more Alkaline

Once the battery leaks its like lighting a fuse to a firework and running away.


If we look closely at Bryce's picture - The reaction has resulted in a copper hydroxide build up in the 68000 cpu socket.  These types of sockets are essentially zinc alloy, once this alloy reacts it will resist electrickery as dendtrites are formed, and then eventually (and I have a CPU this happened to on my Keychain), the socket and Legs of the CPU will flutter off like paper.

I have had the fortune of reparing a lot of Amiga's from this peril, its very common fault, especually on the A500+ and A2000, sadly a battery doesn't have to have a fast-spill either, this can be slow, drawn up by atmospheric heat and pressure- thus it can go directly into the surrounding air and then crystalize on the PCB all over the place.

I have here an A500+ that some one had stored upside down, the battery had leaked all into the top RF sheild... .. I have seen some ugly... but that tin alloy used as a RF shield was an absolute scair! the motherboard PCB... completely spotless...

Yay for peoples strange storage habbits, and a bit YAY for the *pointless* top RF shield! LOL

Anyway sorry for boring everyone.

[MaV]

@Zetr0: This is not boring at all.

At the moment I'm trying to revive to XT boards which have the same problem.

[Womble]

It seems Aussie dishwashers don't have water softenners or anywhere to actually add salt, and the dishwasher tablets we use also don't contain it. Its been a good decade since I left the UK, had forgotten about the salt. Just dawned on me too that the water here is soft, our kettle is about 7 years old and still looks like new. Am original from Cambridge UK and the water there is hard as nails, furs up everything.

Have put plenty of board through a wash and they still look mint many years later.

[Bryce]

@Zetro: A really good description, and not boring. It's just a shame that mostly when people come asking about stuff like this, their computer is usually well beyond repair already.

Also top marks for supplying Gryzor with more new words to randomly add to sentences just to confuse people Sesame Street was brought to you today, by the words: Amphoteric, dendtrites and the letters P and h.

Bryce.

[Gryzor]

*chuckle*

[awergh]

Well I errr tried to get the ribbon cable off the PCB but I think I failed in the worst possible way

Well maybe not quite that bad but I got the ribbon cable off but not the bottom half of the connector I think I did it wrong so I have half a connector and a separate ribbon cable which I dont know how to get the rest of the ribbon cable off as in the bottom cause it doesnt look like I can get it all off cause its conenctected to the PCB with plastic bits.



PS: Bryce can fix everything right??

[awergh]

Oh wait maybe it isn't the end of the world yet, I think I can just press the new ribbon cable onto the sharp pointy sticking out bits with a screwdriver and then use some tape and all is better??

[awergh]

well atatching a new ribbon cable seemed to work one problem though
disc missing I assume this is the ready signal problem and the cable im using has a twist in it, is this a problem?
I was reading although for the 6128 that it was bad to have a twist ?

[Bryce]

If there's a twist in the cable and the drive is connected after the twist, the the drive might appear as B: not A: Best not to have any twist.

The connector half was meant to stay on the board, it's soldered there. But there should be a piece of plastic that clips on top of the cable after it pressed on to the points. Did you loose/break that bit? If that's in place, you don't need any tape.

How about a picture?

Bryce.

P.s. I can't fix everything. Things I can't fix: Broken glass, broken hearts, the European financial situation.....

[awergh]

when I cat or |b it seeks but the led doesnt come on I assume that might be from cutting connections on the ribbon cable or something.

I will try a different floppy ide cable tomorrow since its too late now but at least i have stacks of spare floppy ide cables that i can use.

well looks like i did the right thing with the connector thats good to know i did break the clips though not really knowing exactly what i was doing.

I might not be shorting the right pins for the ready signal though because I am confused. does it have to be pins 33 and 34 connected to the floppy drive so the red wire and the next one ? cause i didnt think the other end could be right because then I would be adding power to the floppy drive where im not supposed to unless im supposed to only short after the connector and not inbetween the floppy drive and the DDI

[awergh]

I untwisted the ribbon cable and this made no difference I think.
Well looks like the Chinon FZ-357 doesn't seem to work so no lazy way out.

but I have another 8 various different spare 3½ FDD to choose from so thats not too much of a problem.

so I'm shorting pins 1 and 2 on the ribbon cable somehow I'm thinking these are the wrong ones but I thought I shouldn't choose pins 33 and 34 because power from the was provided from the FD-1 to the DDI via 33 so I don't think I can do that.

Do I actually have to modify a drive to give the ready signal in this case and can't be lazy and not do any soldering?
Any of these suitable?

Mitsumi D359T5
Teac 235HF 4291-U
Sony MP-F17W-02
Epson SMD-1300
Alps Electric DF354H911C
Samsung SFD-321B (hmm bent pin)
Panasonic JU-257A606P F1019
Panasonic JU-256A888P

I'm even using a 720KB disk so I assume its just ready pain that causes disk missing errors.

[Bryce]

The Mitsumi D359T5 is definitely easy to convert. Two easy changes (solder blobs) is all that required as far as I can remember.

Bryce.

[awergh]

I tried to convert the teac but i think i failed to get proper contact or something so I guess I'll try again with the Mitsumi just I think I should clarify the guide I found before destroying another FDD
http://honi.hucki.de/mitsumi.html

so I move DCH to RDY to get the Ready Signal and and DS1 to DS0 (whats this supposed to do, something with the heads?)

And the last bit with the wire is amiga only right?

Is there an easy way to unsolder those bridges because my attempt with the teac didnt really work I couldn't get it off, I ended up cutting it and probably removing too much solder/ getting brown stuff in the spot making it hard to get proper contact.

Is it possible when I attached the ribbon cable that I didn't do it perfectly so its not working because of that reason, it looks fine but I just wonder thats all?

[Zetr0]

@awergh

The DS0 and DS1 jumper headers are to set the drive to respond as Disk 0 or Disk 1, some drives have more jumpers labled DS2 and DS3 - these are also quite common.

Using an internal Amiga Drive from the A500 / A600 and A1200 will already have the RDY signal modification as default on the device.  If however you are using an external drive unit, then you will need to ensure tha the RDY signal is enabled.

Always tripple check the polarity of the cable from the interface as its very easy to get them back-to-front.


There must be something in the air as I have recently just made (hacked up) two external 3.5" Drives for my Beeb B =)

While I am at it, a Big whoop for Samsung 5volt 1 amp mobile phone chargers =D

[Bryce]

There's no problem with cutting the bridge off. As long as the two points aren't electrically connected any more, then it's fine. Are you sure the Ready and DS0 Bridges are making proper contact?

The cable from the DDI-1 needs to be connected the other way around ie: Turned 180° for the connections to be correct. Connecting it wrongly won't damage the drive or CPC, but it won't work - Will report disc not ready and the disc LED might be permanently lit.

Edit: And yes, you don't need the piece of wire.

Bryce.

[awergh]

I'm not sure the RDY and DS0 bridges are making proper contact  think I made too much mess to fix though, well one of them I was happy with but the other not so much. I think cutting bridges is much easier then unsoldering them, bridges are soo small.

I don't have the LED permanently lit I just put the cable the same way as the old one so I assumed it was right and then connected it to the FDD the wrong way.

I think I meant by the not quite being on properly was that maybe it was slightly out of alignment and the pins weren't going to the right places though it looks fine so I doubt that

[Bryce]

Don't you have a meter to test whether the new bridges make contact? If not, buy a cheap one. It won't be the last time you can make good use of it.

Bryce.

[awergh]

I have a meter though the battery is almost flat I think but I couldn't really see where on top to test the contact only on the bottom which I'm not totally sure its getting contact.

[Bryce]

I'm not sure I understand you? The RDY jumper connects two relatively large solder pads. you should have soldered a wire across these two points. You can then check with the multimeter whether the two points are really connected. It's an SMD PCB, so there won't be contacts on the bottom to test. Can you send us a picture of the current situation?

Bryce.

[awergh]

Oh I should of used a wire whoops I just used a blob of solder hence I'm not totally sure if its connected properly. I might be able to get you a picture though it is potentailly embarrassing because the soldering doesn't look so good or the accident with the screwdriver.

Good thing I can try with another FDD tomorrow although the DS1 bridge (what is the DS0 DS1 things for anyway?) is really small on the Mitsumi drive.

[Bryce]

Yes, using a piece of wire to bridge the gap makes things much easier. Remove the solder blob with a solder pump or de-soldering braid and solder a piece of wire instead.

The DS stands for Drive Select. PCs use two wires to select which one of four drives is being accessed DS0 to DS3, the CPC can only access two drives (A: and B:) and handles these signals slightly differently. PC drives are always set to DS1, but need to be DS0 to work properly with a CPC. Most drives only offer DS0 and DS1 and most PC drive controllers also are only set up for 2 drives.

Bryce.

[awergh]

Well I tried to fix it and I think I did it ok but I had demished the size of one of the solder pads before so I can't be totally sure that it has complete contact I will try the other floppy drive later and it doesnt have any jumpers to worry about unlike the teac.