How to repair an A600 case?

[Jonathan Drain]

I wasn't too careful with an A600, and taking it apart I broke the tabs that hold the case together. How do I fix it?

Related question: Do I need to change any capacitors, like with A1200?

[Cammy]

I don't know how to fix it, it may end up being like my A600, open for business all the time! My A600 had its tabs broken already when I got it, and it looks like the previous owner had tried to seal it with silicone.

You may not need to change your caps yet, but you will eventually as the A600 and A1200 suffer from the exact same problem, and the A600 is a little older. My A600 needs its audio caps replaced, amongst probably others. If you can do the job yourself, I think it'd be best to replace them all and forget about them.

[ajk]

If you want a simple fix, I'd just take some strong transparent or white tape and attach the halves that way on the sides/back. It's easier just to keep an eye out for a cheap replacement case than try to glue the tabs back or anything like that.

[AlfaRomeo]

How do we know when to replace that A1200/A600 caps?.. Just when we see some leakage or other wear type or by the age that the machines have now we should start replace the caps?
It´s certain that sometime the caps will leak or probably they will leak?

[pandy71]

Originally Posted by Jonathan Drain

I wasn't too careful with an A600, and taking it apart I broke the tabs that hold the case together. How do I fix it?

Please attach some photo to show damages.

Originally Posted by Jonathan Drain

Related question: Do I need to change any capacitors, like with A1200?

Only if necessary.

[8bitbubsy]

Originally Posted by AlfaRomeo

How do we know when to replace that A1200/A600 caps?.. Just when we see some leakage or other wear type or by the age that the machines have now we should start replace the caps?
It´s certain that sometime the caps will leak or probably they will leak?

I don't get people saying that Amiga 600, 1200 or 4000 with the old SMD caps shouldn't be changed if they look ok... Believe me, those caps are just as bad as the ones in a SEGA Game Gear (eew).

Around 1989-1994 there was bad SMD capacitors spread around the whole market, they started to leak its electrolytic acid after well some years with active use. I recommend getting rid of them and insert new SMD capacitors... Yours might look fine, but they'll probably leak some day if you start to use the Amiga a lot.
Do it while you can, the acid can tear circuit traces apart and do horrible damages!

The through-hole caps are less likely to leak, but they might dry if they are in a dry or hot environment.

Tips:
* The polarization is very important! Swapping it will result in a cap starting to bulge and presumably blow up like a ballon (and release a gas kind of smoke).
If it's a tantalum capacitor, it can explode instead. Careful!

* Same µF (micro farad) value = very important, depends on the cap usage though. Buffer/filter caps usually do fine with a higher capacitance. In the Amigas I'd use the same values!

* Same voltage rating (or higher, it's just what they can handle) = Important (Using a 16v cap in a 16v circuit is absolutely okay, but the cap will stay alive a bit longer if you use one with a higher voltage rating, like 25v. Sometimes there's no room for any bigger caps -- then you should go for the circuit voltage, or a little bit higher if it's an unusual voltage rating)

* SMD/Through-hole: Not important, but using through-hole capacitors on surface mounted pads makes the pads very fragile! Only do this is a last way out option.

* There's no need for using caps rated 105C°, 85C° capacitors are suited just fine. The Amiga is not an XBOX 360


Wow, that was a wall of text! Hope you learnt something new

[AlfaRomeo]

Very nice and complete explanation

[pandy71]

Originally Posted by 8bitbubsy

I don't get people saying that Amiga 600, 1200 or 4000 with the old SMD caps shouldn't be changed if they look ok... Believe me, those caps are just as bad as the ones in a SEGA Game Gear (eew).

not necessary, replacing can create more problems (unsoldering, soldering stress, risk damage of vias even if replacement is made by skilled person)

Originally Posted by 8bitbubsy

Around 1989-1994 there was bad SMD capacitors spread around the whole market, they started to leak its electrolytic acid after well some years with active use. I recommend getting rid of them and insert new SMD capacitors... Yours might look fine, but they'll probably leak some day if you start to use the Amiga a lot.
Do it while you can, the acid can tear circuit traces apart and do horrible damages!

Nope - year 1999 - 2007 are years more suspected for bad caps, there is no acid in caps (but anyway electrolyte can be corrosive as acid)
http://www.badcaps.net
https://secure.wikimedia.org/wikiped...pacitor_plague

Originally Posted by 8bitbubsy

* Same µF (micro farad) value = very important, depends on the cap usage though. Buffer/filter caps usually do fine with a higher capacitance. In the Amigas I'd use the same values!

Exactly same value is important only where time constant or similar (eg analog audio filters) relations are important. For power supply higher values can be used and this is better (lower should be avoided).
For typical electrolytic cap tolerance is -50% +100% (highly depend from few thing, most important is temperature - higher temperature - higher capacity)

Originally Posted by 8bitbubsy

* Same voltage rating (or higher, it's just what they can handle) = Important (Using a 16v cap in a 16v circuit is absolutely okay, but the cap will stay alive a bit longer if you use one with a higher voltage rating, like 25v. Sometimes there's no room for any bigger caps -- then you should go for the circuit voltage, or a little bit higher if it's an unusual voltage rating)

Modern caps are usually smaller than older then usually newer cap can be higher voltage rated and can have higher capacity than old caps - both are OK for power supply circuits.
Also what is really important electrolytic caps can be used with higher voltages than specified but they shall be formatted before putting in circuit (this is not case for typical caps replacement in Amiga but ca be useful for high voltage circuits).

Originally Posted by 8bitbubsy

* There's no need for using caps rated 105C°, 85C° capacitors are suited just fine. The Amiga is not an XBOX 360

Yes, but those 105C° are usually higher quality than 85C° (usually lower ESR to) then if any choice is possible and price difference is not huge between 105C° and 85C° then 105C° can be preferred one.

Originally Posted by 8bitbubsy

Wow, that was a wall of text! Hope you learnt something new

indeed - thank You!

[8bitbubsy]

My point was that the SMD caps from the 1989-1994 era are very likely to leak, which is dangerous for the circuit. The SMD caps from 1999-2007 aren't that leaky I think, but AFAIK they can fail fast too.
And when I mentioned acid, it was just a slang. The electrolyte really eats on the traces.

You were pretty much repeating what I said, but in more details.

[pandy71]

Originally Posted by 8bitbubsy

You were pretty much repeating what I said, but in more details.

Yep, agree then I thank You once again for review about bad caps.