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Old 08 May 2019, 14:14   #1
Turrican_3
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A600 recapped, but with missing capacitors?!

Hi everyone, I've recently purchased a recapped A600, with the 1.5 motherboard revision.

The unit seems to work flawlessly, but to my huge (?) surprise, I've noticed that not only the person who made the work replaced the capacitors, but he also completely removed a few ones, too!

I can easily notice this because I own a second A600 with the same board revision, and the capacitors are actually there.
(I'm confident people familiar with the matter will instantly spot the - empty - areas I'm talking about)

So my question is... are the missing capacitors actually useful?
I've tried looking on the 'net for some A600 motherboard fix (A1200 style) but so far I've found nothing... on a slightly related note, I can see there is a component missing on that Sony chip as well, at least compared to my old A600.

Any opinion would be much appreciated, and of course I can take more shots if needed.

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Old 08 May 2019, 14:30   #2
ajk
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Those are various power filtering caps, their role is not usually crucial; if the system works fine there is no need to do anything.

The soldering work is a bit crude. It might be that the person doing the recapping installed the through-hole caps first, but didn't then have enough room for the soldering iron to install those last two surface mount ones.
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Old 08 May 2019, 15:04   #3
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Oh, I see, thanks. May I also ask about the other missing one, next to Denise? (I forgot to add that, unfortunately I only have a *very* basic understanding of electronics so even though I saw the schematics, I am basically unable to tell what's actually required and what isn't, not to mention the functionality)
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Old 08 May 2019, 15:12   #4
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If it's working okay now, it'll be down to your PSU putting out a reasonably stable supply.

If you plan on installing an accelerator, and have stability issues, then I'd first look to reinstalling those capacitors.
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Old 08 May 2019, 15:27   #5
Turrican_3
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Got it, thanks to you too!
I have no plans regarding accelerators right now, but that's definitely useful information.

(it is also a bit ironic since I do have stability and other issues on my current A600, the one *with* the capacitors... but I am afraid a recapping is needed on that one)
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Old 08 May 2019, 15:55   #6
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To me it looks like the recapping is uncompleted, and the soldering, is.....crap.
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Old 08 May 2019, 16:54   #7
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That's *not* good to hear... :-\
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Old 08 May 2019, 17:45   #8
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Yeah, those capacitors aren't strictly necessary to the Amiga, once your PSU is working properly it should still run reasonably well. The extra power supply noise isn't a good thing however - it could lead to instability, and extra stress on the various chips in the machine. That particular missing cap is only used for the supply rails of the video output circuitry, but I'd still prefer if it was there, as stray noise might give you wavy noise in the display.

The soldering's not the best, but I've also seen worse.
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Old 08 May 2019, 20:03   #9
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Originally Posted by Turrican_3 View Post
That's *not* good to hear... :-\
Be careful of Italian resellers selling "recapped" mobos. Most of them are total hacks. I bought 2 (or 3?) A600s being sold as spares a bit of time ago and the tracks around the caps are utterly destroyed. I suppose the fact that Amigas and such are selling for a nice amount is attracting a lot of people in for a quick buck by reselling "recapped" mobos for a premium. Problem is, most of these people are working with 5€ soldering irons and have never really worked on SMDs before. But hey, you can do a tidy profit with just a few euros of caps, so who cares if a few Amigas get destroyed along the way! [/sarcasm]

I still haven't had the time to properly look at the two A600s I got, but I hope I'll be able to resurrect them.
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Old 09 May 2019, 09:14   #10
Turrican_3
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Quote:
Originally Posted by Daedalus View Post
The extra power supply noise isn't a good thing however - it could lead to instability, and extra stress on the various chips in the machine. [...]
Hmm, as I said I'm definitely not a pro, but I might try to add the missing capacitors (I've been looking for a cheap SMD station for a while since the first A600 started having instability issues) then, of course after a bit of practice - I definitely do NOT want to damage the Amiga!
Quote:
Originally Posted by jbenam View Post
Be careful of Italian resellers selling "recapped" mobos. Most of them are total hacks. [...]
Guess it's too late (?), but I have to add that the price I paid was relatively fair so I don't feel I've been robbed. I mean, nowadays many sellers keep asking for 150/200 euros for A600s with absolutely no recapping. :-\
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Old 09 May 2019, 09:32   #11
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To be fair, that one particular capacitor probably won't make a huge difference unless you're getting interference in your video out. But if you do go ahead with it (after lots of practice of course) I would recommend removing the through hole capacitor nearby so you can easily access the far pad.
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Old 09 May 2019, 10:33   #12
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Thanks, I really appreciate all of your replies guys. :-)
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Old 09 May 2019, 19:13   #13
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Guess it's too late (?), but I have to add that the price I paid was relatively fair so I don't feel I've been robbed. I mean, nowadays many sellers keep asking for 150/200 euros for A600s with absolutely no recapping. :-\
You just need to be really patient. I've seen some sold for 50-60EURs (which is pretty much the right price for something that old which might die any second). Heck, I bought an A2000 on eBay for 30€ shipped not too long ago. Just don't fall for the scalpers putting a high starting price and/or high buy it now.

Anyways, that's a deed done now - also be careful of the PSU, I had an A600 which looked like it needed a recapping (it was very unstable, especially when using the serial port) and instead it was just the PSU on its way out.
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Old 10 May 2019, 11:46   #14
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also be careful of the PSU, I had an A600 which looked like it needed a recapping (it was very unstable, especially when using the serial port) and instead it was just the PSU on its way out.
Will definitely look into this for the other A600, thanks.
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Old 13 June 2019, 14:41   #15
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Also, I recommend buying some cheap router or other garbage at a local thrift store. Then, practice taking those SMD caps off/on until you can do it in your sleep.

When done properly, the fillet should be a nice curved "ramp" up to pins. Remember, less is more in this scenario.

I cringe when I see those giant blobs of solder on SMD parts.
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Old 14 June 2019, 03:53   #16
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When done properly, the fillet should be a nice curved "ramp" up to pins. Remember, less is more in this scenario.

I cringe when I see those giant blobs of solder on SMD parts.
Same here. The key here is a quality soldering iron, plenty of flux, and very little solder.

I can't stress how important it is to use a good quality flux when doing SMD soldering. You can get away without it for through hole work, but it's absolutely essential for surface mount.
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Old 14 June 2019, 09:38   #17
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Thanks guys!
Please note that this discussion got somewhat outdated though, I've made huge progresses as described in this thread, but this particular A600 is likely being added soon to the recap/repair queue.

(I'm currently working on my 1993 A1200 first, because I really care a lot about it - those A600 instead were purchased second hand, I do care about them as well of course, but not as much as the A1200)
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Old 25 June 2019, 15:39   #18
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While waiting for my soon-to-be-recapped A1200s brand new caps to arrive I decided to return to this A600.

I suspect (it was purchased second hand) by closer inspection that it might have suffered a caps leak, perhaps less severe than the other Amiga I mentioned before on another thread.
But again, I'm definitely NOT sure about this, its just that many surface mounted components have opaque soldering instead of the shiny one, and as far as I understand this is one of the most evident symptoms.

I have another question however, regarding the caps (those are caps, right?) shown in the photo, and the small component (transistor?) immediately below.

I wonder if I can leave those caps as they are... or should I replace them with the default type. And I also wonder (sorry for the low quality photo, can take a better one if needed!) if that transistor is ok or whether it needs some reworking... I'm quite confidend whoever replaced components on this board was less skilled than me, and that would be an achievement in itself!
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Old 25 June 2019, 18:56   #19
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The soldering looks decent enough; not too much solder and nice fillets. Those are ceramic caps so they can't possibly leak. The transistor maybe has too much solder, looks a little blobby.

There have been concerns that ceramic caps might affect the audio due to the piezoelectric effect they have. I have tried this and can't say I'd have noticed any difference, although I didn't do any objective measurements.

If the audio works and sounds good to you, I'd say there is no pressing reason to do anything to those caps, but of course you can if you want it to look more like the original
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Old 26 June 2019, 10:37   #20
Turrican_3
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Quote:
Originally Posted by ajk View Post
The soldering looks decent enough
[...]
The transistor maybe has too much solder, looks a little blobby.
Oh sorry, I was mainly referring to that transistor indeed regarding the soldering quality, I should have phrased it better/clearer.

Nice to hear that anyway, thanks!
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