From Newsgroup: comp.sys.apple2

At last, the inevitable has transpired! On Friday I took my 1980 integer
Apple II out of its box and set it up. Saturday afternoon, after playing
Jungle Hunt, I heard the crackling noise. And saw the whisp of smoke.

This isn’t the first time a RIFA has given it up, so I acted quickly to switch off the power. Carried the still-smoking Apple out of the room, and opened some windows to let in fresh air. Next step is to hunt around and see
if I have an extra capacitor. I think the last machine I had to replace was
a Mac 512K. I may have ordered an extra then.

Service life in this Apple II: about 43 years. Not bad!
--
]DF$
The New Apple II User's Guide:
https://macgui.com/newa2guide/

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From Newsgroup: comp.sys.apple2

On 2024-08-26, D Finnigan <dog_cow@macgui.com> wrote:

if I have an extra capacitor. I think the last machine I had to replace was
a Mac 512K. I may have ordered an extra then.

Are there some known people or places that one can send Apple2 and
classic Macintosh units to for re-capping?

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From Newsgroup: comp.sys.apple2

phigan wrote:

On 2024-08-26, D Finnigan <dog_cow@macgui.com> wrote:

if I have an extra capacitor. I think the last machine I had to replace
was
a Mac 512K. I may have ordered an extra then.

Are there some known people or places that one can send Apple2 and
classic Macintosh units to for re-capping?

The Apple II isn't notorious for failing capacitors (except for this one in
the power supply!), so I don't know of any services for this kind of work.
I have heard of places for older Macintosh models, but I haven't used any of them. There were some people selling capacitor kits for Macs too, which
could save some time as long as you did the work yourself.
--
]DF$
The New Apple II User's Guide:
https://macgui.com/newa2guide/

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From Newsgroup: comp.sys.apple2

In article <dog_cow-1725052556@macgui.com>,
D Finnigan <dog_cow@macgui.com> wrote:

phigan wrote:

On 2024-08-26, D Finnigan <dog_cow@macgui.com> wrote:

if I have an extra capacitor. I think the last machine I had to replace was >>> a Mac 512K. I may have ordered an extra then.

Are there some known people or places that one can send Apple2 and
classic Macintosh units to for re-capping?

The Apple II isn't notorious for failing capacitors (except for this one in >the power supply!), so I don't know of any services for this kind of work.
I have heard of places for older Macintosh models, but I haven't used any of >them. There were some people selling capacitor kits for Macs too, which
could save some time as long as you did the work yourself.

I can think of only two classes of devices where recapping is likely to fix
a problem:

1) Computer equipment (and maybe other electronics more generally) of a
certain age that was built with counterfeit electrolytic capacitors
that tended to bulge, leak, and fail:

https://en.wikipedia.org/wiki/Capacitor_plague

Apple IIs (and 68K Macs, while we're at it) predate this issue by several
years.

2) Really old devices (mostly running on vacuum tubes instead of solid-state
devices) that used wax- or plastic-covered paper capacitors in which
failure of the wax covering would cause the paper dielectric to absorb
moisture, altering its properties.
--
_/_
/ v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/ Top-posting!
\_^_/ >What's the most annoying thing on Usenet? --- Synchronet 3.21e-Win32 NewsLink 1.2

From Newsgroup: comp.sys.apple2

Scott Alfter <scott@alfter.diespammersdie.us> wrote:

In article <dog_cow-1725052556@macgui.com>,
D Finnigan <dog_cow@macgui.com> wrote:

phigan wrote:

On 2024-08-26, D Finnigan <dog_cow@macgui.com> wrote:

if I have an extra capacitor. I think the last machine I had to replace was
a Mac 512K. I may have ordered an extra then.

Are there some known people or places that one can send Apple2 and
classic Macintosh units to for re-capping?

The Apple II isn't notorious for failing capacitors (except for this one in >> the power supply!), so I don't know of any services for this kind of work. >> I have heard of places for older Macintosh models, but I haven't used any of >> them. There were some people selling capacitor kits for Macs too, which
could save some time as long as you did the work yourself.

I can think of only two classes of devices where recapping is likely to fix
a problem:

1) Computer equipment (and maybe other electronics more generally) of a
certain age that was built with counterfeit electrolytic capacitors
that tended to bulge, leak, and fail:

https://en.wikipedia.org/wiki/Capacitor_plague

Apple IIs (and 68K Macs, while we're at it) predate this issue by several
years.

2) Really old devices (mostly running on vacuum tubes instead of solid-state
devices) that used wax- or plastic-covered paper capacitors in which
failure of the wax covering would cause the paper dielectric to absorb
moisture, altering its properties.

The Wikipedia article you cited acknowledges there are other causes for capacitors to fail than counterfeit electrolyte.
One being that they can dry out over time.

I stored a IIgs keyboard in my roof space (which gets hot in summer) and it didn’t work after several years. After a lot of troubleshooting and getting nowhere the caps were replaced as a what-if and it now works.

Regards
Andrew
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From Newsgroup: comp.sys.apple2

D Finnigan <dog_cow@macgui.com> wrote:

phigan wrote:

On 2024-08-26, D Finnigan <dog_cow@macgui.com> wrote:

if I have an extra capacitor. I think the last machine I had to replace
was
a Mac 512K. I may have ordered an extra then.

Are there some known people or places that one can send Apple2 and
classic Macintosh units to for re-capping?

The Apple II isn't notorious for failing capacitors (except for this one in the power supply!), so I don't know of any services for this kind of work.
I have heard of places for older Macintosh models, but I haven't used any of them. There were some people selling capacitor kits for Macs too, which
could save some time as long as you did the work yourself.

I agree that the capacitors used in Apple IIs are very reliable. In fact,
all the common capacitor issues are inside the power supply.

There are two kinds of problems that are common:
electrolytic filter capacitors in the “line side” of the supply, and the X2 type polypropylene capacitor directly across the line input intended to
protect the supply from line spikes and reduce RF interference conducted
from the supply to the line.

The second type (and the type reported by the original poster) is trivial
to dignose by the horrendous odor! The X2 capacitor across the line has a value in the 0.5-2.0uF range, and a 230vac rating. They are widely
available for under a dollar, and are made in a rectangular plastic
package. The power supply will need several days of “airing out” before it’s nice to be around. ;-)

The first (electrolytic) type of failure is rarely sudden (or odorous), resulting from a long, gradual decline in filtering the raw 280vdc from the bridge rectifier connected to the AC line. If this happens, it decreases
the ability of the power supply to operate the computer. There are usually
a couple of these, both the same rating: about 100uF and 300vdc. They are also widely available, and it makes sense to replace them both.

There is a more sudden failure mode of these electrolytics: shorting. If
this happens, the fuse will blow, but often the bridge rectifier will also
be shorted, and it should be replaced before power is reapplied.

BTW, “re-capping” is an artifact of 1) old vacuum tube (hot, high voltage) equipment, 2) old and not very reliable paper-insulated or wet electrolytic capacitors, and 3) folks not very skilled in the repair of such equipment.
The combination of these ingredients has led to an almost superstitious tendency to “replace ‘em all”. This is almost never necessary, and often results in needless damage.

In the case of low-voltage, solid state electronic equipment, re-capping is certainly unnecessary and potentially damaging. (Note that power supplies
are NOT low-voltage.)
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
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From Newsgroup: comp.sys.apple2

Michael J. Mahon <mjmahon@aol.com> wrote:

BTW, “re-capping” is an artifact of 1) old vacuum tube (hot, high voltage)
equipment, 2) old and not very reliable paper-insulated or wet electrolytic capacitors, and 3) folks not very skilled in the repair of such equipment. The combination of these ingredients has led to an almost superstitious tendency to “replace ‘em all”. This is almost never necessary, and often
results in needless damage.

In the case of low-voltage, solid state electronic equipment, re-capping is certainly unnecessary and potentially damaging. (Note that power supplies are NOT low-voltage.)

While I don’t have your experience, I have heard from others who have extensive recapping experience, that over time, electrolytic capacitors in equipment that is not used can degrade. To prevent degradation, the recommendation is to use the equipment for 30mins a year to keep it
exercised.

If the equipment hasn’t been used for an extended period of time then exercising the equipment may not result in satisfactory function.

Regards
Andrew


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From Newsgroup: comp.sys.apple2

On 2024-09-04, Michael J Mahon <mjmahon@aol.com> wrote:

D Finnigan <dog_cow@macgui.com> wrote:

phigan wrote:

Are there some known people or places that one can send Apple2 and
classic Macintosh units to for re-capping?

The combination of these ingredients has led to an almost superstitious tendency to ???replace ???em all???. This is almost never necessary, and often
results in needless damage.

Unfortunately, the Mac LCIII that I would like to get working again most definitely has capacitor issues as you can visibly see leakage around
several of them on the board. Unfortunately I don't know if there are
any further issues yet.

The other unit that I would like to get working is a IIgs. Right now
when powered on it only shows thick horizontal black and white bars on
the screen. I'm thinking it's most likely some of the onboard RAM that
is the culprit (ROM3), but there may also be a sign of a leaked cap or
two in that one as well.
Unfortunately, the Mac LCIII that I would like to get working again most definitely has capacitor issues as you can visibly see leakage around
several of them on the board. Unfortunately I don't know if there are
any further issues yet.

Perhaps I should have said "for fixing" rather than "for re-capping". ;)
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From Newsgroup: comp.sys.apple2

phigan <wwiv@bbs.penisys.online> wrote:

The other unit that I would like to get working is a IIgs. Right now
when powered on it only shows thick horizontal black and white bars on
the screen. I'm thinking it's most likely some of the onboard RAM that
is the culprit (ROM3), but there may also be a sign of a leaked cap or
two in that one as well.

Did you mean vertical columns of white and black?
This is usually a sign that the CPU has not kicked in. Has this machine had
an accelerator in the past? Perhaps the cpu socket is not making good
contact with the cpu.
I have not heard of many people having issues with the IIgs capacitors.
They are not surface mounted and therefore avoided the bad caps plague.
Regards
Andrew



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From Newsgroup: comp.sys.apple2

"scott@alfter.diespammersdie.us" wrote:

2) Really old devices (mostly running on vacuum tubes instead of
solid-state
devices) that used wax- or plastic-covered paper capacitors in which
failure of the wax covering would cause the paper dielectric to
absorb
moisture, altering its properties.

About a year later... Learned something interesting today..

Leon
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