Replacing A1200 Caps with Solid State Caps

[trip6]

I am thinking about having my buddy (who owns an electronics repair shop) replace all the caps on my A1200 with Solid State Caps... Has anyone run into any problems with doing this? Does anybody know what spec caps I will need and how many of each? Your help is greatly appreciated. I heard that rubicon are a good brand.

[jsixis]

all of the capacitors are solid state
with that cleared up, it can't possibly hurt provided they are decent caps of the same rating, it ain't "stereo" gear so I would not stray far from the actual capacitors.

Now if your talking about the cap keys, why bother haha

[gertsy]

I am thinking about having my buddy (who owns an electronics repair shop) replace all the caps on my A1200 with Solid State Caps... Has anyone run into any problems with doing this? Does anybody know what spec caps I will need and how many of each? Your help is greatly appreciated. I heard that rubicon are a good brand.

Does the A1200 have the same CAP problems as the A4000.?  I have an ATECH A1200 that was used consistently as a video generator for years, and more years by me. If its a risk why not change them, but if its not, best leave things unbroken alone...

[Karlos]

I was thinking about this but an electronics engineer I know has told me that it's a bad idea and that you should replace like for like; ie replace electrolytics with electrolytics and solid state with solid state. Replacing electrolytics with tantalum, for example is potentially a bad idea. Their failure characteristics are quite different. An electrolytic will fail gradually and tend to open-ircuit, a tantalum will tend to fail suddenly and closed-circuit. The latter is not a good prospect.

[ognix]

Hello!
I investigated a bit regarding (aluminum) electrolytic capacitors and the tantalum ones.

It seems that life expectancy of the lastest ones is much longer than the classic aluminum electrolytic ones (and no short-circuit in case of failure - which happens at voltages higher than their rating).

Check out:
http://en.wikipedia.org/wiki/Electrolytic_capacitor

and this interesting article about capacitors "plague":
http://en.wikipedia.org/wiki/Capacitor_plague

and more about tantalum capacitors:
http://www.engineersedge.com/instrumentation/tantalum_capacitors.htm
http://my.execpc.com/~endlr/reliability.html

even if:
http://www.electronicspoint.com/tantalum-caps-long-shelf-life-t134737.html
http://www.itiomar.it/pubblica/Telecomunicaz/lezioni/3_anno/Cap-Ta-1.pdf

Anyway a friend of mine substituted aluminum electrolytic capacitors with tantalum ones in an A4000T, and everything works fine (planning to do the same in a faulty A4000 motherboard I have).

[Castellen]

As I've mentioned before in several similar threads:

Tantalum capacitors should generally not be used on DC power supply rails for AC decoupling. The reason is that the low equivalent series resistance of the tantalum capacitor results in a very high momentary inrush current when the power supply is turned on. The high current flow causes the capacitor to heat up internally, which can result in it going short circuit and sometimes exploding. Google 'explode' and 'tantalum' to find out more.

It's possible you might get away with it forever, but it's entirely possible that one of the capacitors will fail in the future.  I've seen sudden failures happen in poorly designed equipment that has been in use for over 10 years.

Replace the original electrolytic capacitors with modern versions of a quality brand such as Panasonic or Rubycon.  If you select high temperature versions ( >100°C) they'll provide an even longer working life at room temperatures, though even standard good quality capacitors should be fine.

See this thread and this thread for more discussion on the subject.

And for the record, I've written an Amiga audio repair guide here and SMD capacitor replacement guide here.

Online price list here if you need to buy parts.

[tone007]

I powered up an IMSAI 8080 with the cover off that hadn't been on for years and one of the tantalum capacitors exploded and shot a chunk of itself across the garage and bounced loudly off of the door.  It was very exciting.

[ognix]

As I've mentioned before in several similar threads:

Tantalum capacitors should generally not be used on DC power supply rails for AC decoupling. The reason is that the low equivalent series resistance of the tantalum capacitor results in a very high momentary inrush current when the power supply is turned on. The high current flow causes the capacitor to heat up internally, which can result in it going short circuit and sometimes exploding. Google 'explode' and 'tantalum' to find out more.

Thanks a lot for this clear explanation: low ESR on power on explains short-circuit behaviour in some occasions.

It's possible you might get away with it forever, but it's entirely possible that one of the capacitors will fail in the future.  I've seen sudden failures happen in poorly designed equipment that has been in use for over 10 years.

Replace the original electrolytic capacitors with modern versions of a quality brand such as Panasonic or Rubycon.  If you select high temperature versions ( >100°C) they'll provide an even longer working life at room temperatures, though even standard good quality capacitors should be fine.

See this thread and this thread for more discussion on the subject.

And for the record, I've written an Amiga audio repair guide here and SMD capacitor replacement guide here.

Online price list here if you need to buy parts.

Thanks once more fore references and hints (and sorry for late reply).

Ciao!
   Luca "OgniX"   \8^)

[stachu100]

I powered up an IMSAI 8080 with the cover off that hadn't been on for years and one of the tantalum capacitors exploded and shot a chunk of itself across the garage and bounced loudly off of the door. It was very exciting.

Are you sure it was tantalum capacitor?
Not Aluminum electrolytic capacitor?

[tone007]

Are you sure it was tantalum capacitor?
Not Aluminum electrolytic capacitor?

100% sure.  It's not the first exploded one I've seen, either, just the first I witnessed exploding.  The molten orange streak and projectile are something I wouldn't expect you could get from an electrolytic, though I've never tried.

[A1260]

I powered up an IMSAI 8080 with the cover off that hadn't been on for years and one of the tantalum capacitors exploded and shot a chunk of itself across the garage and bounced loudly off of the door.  It was very exciting.

LOL! better leave the cover on the next time.... anyway how long do you think the c64 capacitors will last before take off?

[stachu100]

100% sure. It's not the first exploded one I've seen, either, just the first I witnessed exploding. The molten orange streak and projectile are something I wouldn't expect you could get from an electrolytic, though I've never tried.

As far as I know there is no tantalum capacitors inside IMSAI 8080... :confused:
Only aluminum electrolytic capacitors were used.
Unless someone did an extensive upgrade.

[CLS2086]

Hi,
try to look on the photo gallery what I did with a A1200 ;-)

[tone007]

As far as I know there is no tantalum capacitors inside IMSAI 8080... :confused:
Only aluminum electrolytic capacitors were used.
Unless someone did an extensive upgrade.

...maybe you've only seen empty ones?

Not a heck of a lot of anything in just the case. (and no, it wasn't one of the giant power supply capacitors that exploded.)

Start adding an assortment of some of the hundreds of various boards to make the system run, however, and you're bound to run across some tantalum capacitors.



I believe the one that blew up in mine was on a memory board.