Recapping

[Sim085]

Hello, I read on another thread that "Recapping is not required on A500s".
http://eab.abime.net/showpost.php?p=1177071&postcount=2

Does this also apply for the A500+
I know the A500+ can have battery leaks. But what about the capacitors?
Also why then does the A1200 need recapping?

[Jope]

The caps are "as good" as in the A500. Sometimes they fail, but not as often as in the surface mount Amigas.

[Daedalus]

Yep, failures aren't as common with that type of capacitor, and when they fail, they don't normally cause as much damage as the type used in the A1200. The A1200 (and 600, CD32 and 4000) all use surface mount capacitors, which were less mature technology (and were cheap), so they fail more or less predictably around now. And when they fail, they fail more dangerously because they leak directly onto the circuit board underneath them, corroding traces slowly until the machine starts to fail. And, because this corrosion is hidden underneath the capacitors, it's often not obvious to the casual observer until it's too late.

[Franchute13]

Hi.

Check that the capacitors are not leaking liquid.
regards

[Sim085]

How?

I mean how to know if they are leaking directly onto the circuit board underneath themselves? Is there a method?

Originally Posted by Franchute13

Hi.

Check that the capacitors are not leaking liquid.
regards

[ajk]

There will be dull solder joints and oily residue around the capacitors when examined closely.

[Jope]

Yep, no wet/dried up puddles of electrolyte should be visible.

[Sim085]

Was wondering; can the A1200 when recapping be recapped with capacitors which don't leak... or it doesn't work like that (they need to be exactly the same)?

[Jope]

People have used other types of capacitor too. Ceramic and tantalum ones.

Ceramic ones are a bad idea, their capacitance depends on the voltage. You need to be extra sure that they have the same value when installed.

Tantalum may explode if there is a problem, but that probably isn't such a big issue in normal use. :-)

[ajk]

You can, tbtorro for example does this with polymer capacitors which don't have liquid electrolyte. Ceramic capacitors can also be used although the jury is still out on whether they are a suitable replacement or not. But even good quality modern electrolytic replacements are not very likely to leak (the original ones Commodore used were early technology and probably also chosen based on cost rather than lifetime).

[Daedalus]

The same type of capacitors are much longer lasting these days, and you can get extra long life versions too. Alternative types are also available that should never leak, such as inorganic polymer capacitors. These are much more expensive, but also should last the lifetime of the rest of the machine.

Some people use ceramic or tantalum capacitors which also should never leak, but they have totally different characteristics so I don't personally use or recommend them for this purpose.

[fordav1]

On A500/A500+ the two blue caps on the top left of the board at the back near the VIDIOT Hybrid and RGB 23 pin port should be changed if they are original SHOEI 3300uF 10V (C401, C402). When either of those two caps fail they can short internally. The +12v input power to the VIDIOT is filtered through C401 and if it shorts it *will* blow up the VIDIOT. When that happens R405 (4.7 ohm 1/2W) will also smoke and burn. I have seen that a couple of times and I had to get a replacement VIDIOT self-build kit because the VIDIOT was toasted. Clearly Commodore knew this was a problem because the earlier rev 3/5 board uses a 4.7 ohm 1/4W resistor at R405 and they probably had issues with burning resistors so increased it to 1/2W in later rev 6 and rev 8 boards.
So basically anyone with an A500/A500+ should change those two caps to quality Japanese caps before they go bad and blow the Video Hybrid....

[Sim085]

From where do you guys buy your capacitors and for which ones would you go?

I found a local technician who is happy to do this job for me. He told me he is sure he has any capacitor required for the job however I prefer to source them myself to make sure these are of good quality.

Originally Posted by Daedalus

The same type of capacitors are much longer lasting these days, and you can get extra long life versions too. Alternative types are also available that should never leak, such as inorganic polymer capacitors. These are much more expensive, but also should last the lifetime of the rest of the machine.

Some people use ceramic or tantalum capacitors which also should never leak, but they have totally different characteristics so I don't personally use or recommend them for this purpose.

[MigaTech]

The Capacitor kit for 500 used to be available from AmigaKit. Now they only stock the 600/1200/CD32/4000 kit, found here;

http://amigakit.amiga.store/catalog/...oducts_id=1137

Also check the seating of all the IC's on that A500 a very common issue which is often missed. They are know to start to raise up after long periods of time. Specially if the machine has not been used and stored. < Position of storage makes a difference, if it is upside down for instance. <I knew of an A500 Plus which was stored upside down and the battery leaked but didn't damage the board.

So all seems silly but it is true that these things can happen. Heat and long running use can also be contributors to IC's raising out of dill sockets.

Another common A500 fault is the ODD / EVEN CIA's < these get damaged from people plugging in or unplugging devices when power to the Amiga is ON. < NEVER DO THIS !!

[Sim085]

Hi sorry I wasn't clear, at the moment I am looking for capacitors for my A1200 not the A500 given that the A500 has less risk of leaking.

Originally Posted by MigaTech

The Capacitor kit for 500 used to be available from AmigaKit. Now they only stock the 600/1200/CD32/4000 kit, found here;

[Signman]

Is this a capacitor leak?
I have a 2000 MB that won't boot beyond light gray screen.
Tried everything, battery had some leakage but I believe no damage.

By the way what is that wire for on the back, it seems to lead from a expansion slot on the board to the first Cia chip.

[dlfrsilver]

looks like flux residues never cleaned to me.

[Daedalus]

Originally Posted by Sim085

Hi sorry I wasn't clear, at the moment I am looking for capacitors for my A1200 not the A500 given that the A500 has less risk of leaking.

I generally buy mine from either Farnell / Element 14 or RS Components. They both stock many different options for the capacitors - I go for Panasonic, Nichicon or Rubycon personally, and make sure to choose a series with a high lifetime rating. For example, the last set I ordered were Nichicon CB series, which are rated for 7000 hours at 105 degrees C.

[Sim085]

Thanks Daedalus, is there a definitive list somewhere. I have done a search on the internet but some are from 2009 and sometimes not very clear.

Originally Posted by Daedalus

I generally buy mine from either Farnell / Element 14 or RS Components. They both stock many different options for the capacitors - I go for Panasonic, Nichicon or Rubycon personally, and make sure to choose a series with a high lifetime rating. For example, the last set I ordered were Nichicon CB series, which are rated for 7000 hours at 105 degrees C.

[Daedalus]

John Hertell has a good list of part numbers covering all the SMT Amiga models. Scroll down this page for details. He uses Panasonic Hybrid capacitors, which are about as good as you can get.