Replacing Caps in a 600

[Chartus]

Whats the easiest way to replace the SMD capacitors on a 600.  Some of them are in tight places.  Is there any way to maybe snip them off without hurting the motherboard?

[alexh]

I'd be interested to know exactly which ones can be faulty and what their values are (some sort of nice diagram pwease!)

[Damion]

Chartus wrote:
Whats the easiest way to replace the SMD capacitors on a 600.  Some of them are in tight places.  Is there any way to maybe snip them off without hurting the motherboard?

The safest way is hot air. Personally, I apply a smidge of fresh solder, heat one side at a time, and gently wiggle the cap a small amount one side at a time (with a small screwdriver) in one direction, until it comes off. A good quality iron (I use a Hakko 937) is a must. Although it looks impossible, replacing the audio caps isn't too difficult with the right sized tips, a steady hand and lots of patience.

If you're careful, you won't lift pads... unless the joints are already damaged from the electrolyte, in which case some additional repair may be unavoidable. TBH I haven't yet found the best method for dealing with heavily corroded joints/pads. Best thing is to get to them before you have to worry about that.

Some people replace with tantalum caps, I simply order the original type in a quality brand (Panasonic) since I'm a stickler for originality.

@alexh

IMHO - EVERY single one should be replaced. I've found that with the Commodore-era A1200/A600, they've all leaked a bit, even if there are no visible signs. Every one on my A1200 and A600 boards emitted that tell-tale "fishy" odor during removal. The caps on my Escom A1200 seemed to be OK, but I replaced them anyway after witnessing what nasty things can happen when they leak... two seriously fux'd A600 motherboards in my case :boohoo:

Probably not really necessary to replace the thru-hole caps, but I do anyway with a quality replacement (like Chemi-Con KZE series) while I'm at it with the others.

There's a link on this page to the A600 schematics, which list all the needed caps. (I could post the Digi-Key part numbers for anyone in the US who wants to order them without the hassle of looking everything up.) The A1200 uses all the same caps, so order a bunch and do them all. :-)

-edit-

Just thought I'd add, there's some fantastic info on this subject here. Really saved me from making a mess of things!

[Chartus]

I have replaced the ones by the floppy drive.  It wasn't too hard but the pads were damaged on 2 of them from the leaing caps.  It looks like the ones by the audio out jacks are leaking and a few by the Sony encoder chip thingy.  Sorry no pics, I just broke my camera over the holidays.

[Chartus]

Yep its the audio caps that I was looking at.  They are in a tight spot.  I also have a Hakko iron but I am not that skilled with it yet.  I am trying to replace all of the smd caps and they are probably the hardest to get to.  I was hoping for an easier way.  That was a nice link to loo at. Lots of interesting and useful things to read.  Thanks

[klx300r]

the links D gave are very helpful and I also will stress to replace ALL your caps once you start...they are very inexpensive and even if some look good they are still 20+years old and will eventually leak

[Damion]

A couple (crappy) shots of an A1200 I did:

pic 1

pic 2

The light reflection makes the solder joints appear a bit "blobbish", but they look OK in person. ;-)

[alexh]

-D- wrote:
IMHO - EVERY single one should be replaced. There's a link on this page to the A600 schematics, which list all the needed caps.

Erm thanks, big help. How many are there on an A600?

I'm not sure I really believe you that all the capacitors are susceptible to failure and I dont think I (or anyone?) could be arsed to replace them all? Could they? It would take hours. Not to mention the high risk to most users of a mistake.

You think the failures are just due to poor quality capacitors and buying top quality will fix for the future? Not that they were the wrong values / type / power rating?

When they eventually break I guess I'll bin them and just use WinUAE :-(

[Damion]

alexh wrote:

-D- wrote:
IMHO - EVERY single one should be replaced. There's a link on this page to the A600 schematics, which list all the needed caps.

Erm thanks, big help. How many are there on an A600?

There are around 20 total (including the 4 big thru-hole caps), the amount and values are spelled out clearly in the schematics.

I'm not sure I really believe you that all the capacitors are susceptible to failure and I dont think I (or anyone?) could be arsed to replace them all? Could they? It would take hours. Not to mention the high risk to most users of a mistake.

I can only go by what I've seen, which is that they leak at random and not just the audio caps as is oft-repeated. *All* of them had leaked to some degree on my C= made A1200. Random locations on two A600 boards (audio caps fine on both of those). Escom board was fine, but is also newer.

It does take a little time to replace them, but things go quickly after getting the hang of it. Less than an hour a board I would say. And I agree - there absolutely is a risk (particularly if the leaked electrolyte has had a chance to cause damage) and I stress that sending the board to an expert like Anthony Hoffman (Castellen) is probably a real good idea.

You think the failures are just due to poor quality capacitors and buying top quality will fix for the future? Not that they were the wrong values / type / power rating?

Unfortunately I can't say, maybe an expert can chime in. From my amateur perspective, the quality of the caps used by C= was poor, especially considering the random nature of those that leak. I noted from earlier posts by Castellen that he uses the original type/rating in a quality brand, so I went with that.

When they eventually break I guess I'll bin them and just use WinUAE :-(

It's no biggie, a couple of evenings and you can have all those POS caps replaced. I bet you'll get tired of having all that old junk set up around the house long before it actually breaks. ;-)

[Retro_71]

Just a little bit of a thread High Jack. Are the number and type of caps in the A1200 the same as the A600 and if not does anyone have a list of parts?
Also is there a total list for A3000 and A4000 Caps?

I just got myself a SMD hot air and solder rework startion so i plan to replace all my Amiga's with New caps.
Almost forgot need a caps list for the A500 and A2000(or should i not worry about them since one really mentions them much?)

Regards

[rkauer]

 The A600 & 1200 shares the same capacitor values and even the same board code!

 Yes, they are A3000 and 4000 schematics floating around, and they use the pretty same board code from the ancient A2000.

[Retro_71]

Thanks rkauer, now to track down values and quantities.
Unless some helpful person already has already got them....  :-D   ;-)

[countzero]

alexh wrote:

I'm not sure I really believe you that all the capacitors are susceptible to failure and I dont think I (or anyone?) could be arsed to replace them all? Could they? It would take hours. Not to mention the high risk to most users of a mistake.

I can finish a a600 board about 30-45 mins in one sweep. I don't bother with hot air though. Just wiggle the cap gently in one direction, with a beak head plier until it comes off. if you do it right way, you won't lift any pads, the legs are already corroded by this time so it will come off eventually. When you get the head, the legs are in the open so just remove the plastic bottom (if it's still there) and desolder the legs and any remaining solder with a solder braid. I have yet to lift a pad by this method (and I did 3x1200, 2x600, 3x4000 boards till now). Of course practising on a A600 first is a good idea before working on something like A4000 till you get the feel of it.

[xPhilx]

@Retro_71
I recently replaced the caps on one of my A4KD mobos, here's the cap list:-

10 X 47uF / 16V
1 X 100uF / 6.3V
5 X 22uF / 16V *
1 X 10uF / 35V
2 X 4.7uF / 25V

* Optionally (recommended) you can (should) replace the two audio 22uF/16V caps at C443 and C433 with non-polarised caps, I used 22uF/35V.  All other caps remain polarised radial.



DISCLAIMER: I'm no expert, just read and research lots and lots .

[Chartus]

Whats a beak head plier?  Do you wiggle it back and forth?  I have already replaced 5 caps in my computer with lifted pads on 4 of them.  Probably corrosion :-D.  Thats my story and I'm sticking to it.  Wasn't too hard to fix but I would rather not have it happen again.

Update: I feel stupid.  Of course I know what a beak head plier looks like.  I know what it looks like but not the name, if that makes any sense :-)