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Old 08 September 2016, 14:44   #1
lord of time
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Smelly Miggy!!!

Hiya guys and girls - I have got a rather odd and anoying issue with my A600... I recently received my vampire 2 and its great so as you can imagine my little 600 has been getting a bit of a work out how ever the last few days I can smell what can only be described as a fishy/chemically smell when the machine is on, not only that but my sound output seems to be missing some channels. My guesss was caps but I have gone over the board with a fine tooth comb and cant see any leakage or bulges nor can I smell anything when the system is powered down. Any ideas?
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Old 08 September 2016, 14:46   #2
dlfrsilver
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the capacitors. If it smells rotten fish, they are dead.

and you must replace them !
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Old 08 September 2016, 15:45   #3
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Yep, that's capacitors. Get them replaced before their guts dissolve your A600's motherboard! Often they don't give any visual indication as they leak downwards, corroding the traces underneath them where you can't see.
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Old 08 September 2016, 18:44   #4
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Thanks for confirming my thaughts guys... I am fairly handy with a soldering Iron if I was to purchase one of the replacement cap kits of evil bay what advice would you give in regards to installing the little buggers?
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Old 08 September 2016, 19:49   #5
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It's a lot harder job than it looks. The ones near the keyboard and the audio connector are really hard to do. you'll need good eyes or a microscope to see the little solder tabs. Even removing the caps is prone to disaster.

You could end up knackering your motherboard if you're not careful, unless you are really 100% sure that you can tackle this then I would send the board to someone who can.
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Old 08 September 2016, 23:58   #6
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Indeed, with just an iron it will be extremely tricky to change them all without causing damage. I'm not saying it's impossible, just very tricky. A hot air rework station is a far better tool for the job and can be used to replace them without any damage to plastic parts.

The important thing to do is practice as much as you can before you attempt it on your Amiga. Any old-but-working PC graphics card, USB card or motherboard will do - just make sure it works again after you've taken off a bunch of components and put them back on.
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Old 09 September 2016, 01:49   #7
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i have replaced caps on mine by standard capacitors, not SMD.
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Old 09 September 2016, 16:54   #8
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Being handy with a soldering iron is not enough. You need experience (can be gained as mentioned above), generous use of flux and preferably two soldering irons.
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Old 09 September 2016, 20:14   #9
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Check your board revision also. On Rev1 "A300" the pads are too small making removing and resoldering trickier. Later revs are much easier but only if you have the right tools, and flux, lots of flux.

If you only have one normal soldering iron, the pliers method of removal is probably best. Solder wick will not help, except for cleaning the pads after the caps are removed.

In order of preference for me for removal

Soldering Tweezers
Hot air
Pliers
Pair of Irons
Single Iron

If you are using any kind of method with heat, including hot air, it helps to Clean any bad corrosion off and put a spot of fresh solder on the contacts first. Shiny joints give a better thermal contact therefore less time spent heating. If you stick an iron on a crusty green pad, the pad will probably detatch before the solder melts.

I was very dubious about the pliers method but have had 100% success when using it. I think the trick is to break the cap legs by fatigue not twist/snap them in one go, that way the mechanical force is not enough to damage the pad. Pinch the can slightly with the pliers, to ensure a good grip, press down towards the board slightly to ensure no upwards force is applied to the pad, then repeatedly twist the cap CW and CCW about 15-25 degress. Reverse the rotation when you feel the resistance start to increase. Also, try to avoid any sideways forces, rotation only! It can take quite a few repetitions for the legs to break but don't get impatient.
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Old 09 September 2016, 21:32   #10
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I've seen a guy who is very experienced with electronics AND using a very good hot air station (in a very modern electronics lab), and the caps near the keyboard/audio connectors gave him a *lot* of trouble indeed.

He managed to do it, but it took a very long time, and some headache
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Old 10 September 2016, 01:12   #11
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I don't find the caps behind the keyboard connector particularly difficult, but I always remove the top part of the connector and always give it a few layers of kapton tape. Sometimes the corrosion underneath is so bad that the solder has trouble melting but thankfully I've never had that issue at the keyboard connector. *Touches wood*
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Old 24 September 2016, 02:50   #12
lord of time
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Thanks for all the help guys - I have purchased a recently recapped board and removed my old board... It had become really unstable random resets, missing sound channels, grey screens on boot so gonna send it for a recap and if its too far gone I am gonna steal its ram to do the 2mb chip ram mod on my replacement board!
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Old 24 September 2016, 17:11   #13
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I wouldn't bother with the piggy back chip RAM mod. It would be different if 1MB cards were unavailable or it freed the connector for another use but as it is, not worth it.

It's a slightly tricky mod that is even trickier to undo if you mess it up or it turns out you have bad RAM chips. The piggy backed chips can also foul on the floppy drive bracket when you screw it down.

But it is a neat trick so if you're determined then go for it.
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Old 24 September 2016, 19:24   #14
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I agree. It's a nice mod in a "because I can" sort of way, but personally I'd rather repair the old board and either keep it as a spare or sell it to someone else who needs one. A recap (and probably trace repairs) will likely fix it though.
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