M105 capacitor ratings

Archived from groups: comp.sys.palmtops.pilot (More info?)

In article <2vudavF2nip49U1@uni-berlin.de>, No Spam <gogo@fake.com> wrote:

> I've seen several articles on replacing the capacitor in Palm M105s to
> keep them from clearing the memory when the battery is changed. They
> say that the original is a 0.22Farads, this doesn't sound right.

A low voltage 0.22F capacitor is a reasonable choice as a backup power
source so the primary power source can be replaced. Super capacitors
of several Farads are available, but the space inside the M105 probably
limits you to this 0.22F capacitor. Note that this type of capacitor
is only suitable as a backup power source for low power devices. The
capacitance is high, but so is the internal impedance making them
unsuitable for other type of applications capacitors are used for.

> Is it
> really a .22 micro Farad?

A 0.22µF capacitor isn't a reasonable choice as a backup power source
unless the time it takes you to replace the primary power source can
be measured in microseconds.

--
Göran Larsson http://www.mitt-eget.com/

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No Spam <gogo@fake.com> wrote:
>I've seen several articles on replacing the capacitor in Palm M105s to
>keep them from clearing the memory when the battery is changed. They
>say that the original is a 0.22Farads, this doesn't sound right. Is it
>really a .22 micro Farad?

Yes, that's the value. The actual part is a Dynacap double layer capacitor made
by Elna in the USA. This is a 3.3v .22F unit with Elna part number
DSK-3R3H224-H. These were reported here as hard to find or purchase in single
quantities. .22F (farads) is the same as 220uf (microfarads) which is the way
most caps are labeled these days. You can easily find tubular caps at or near
this value at Radio Shack or Frys, but most are too large to fit inside the
m105. I did some experimenting awhile back and found that you could go as low as
50uf and still get about 40 seconds to a minute to change the batteries. (The
original .22F cap gave me several minutes even though the manual states only a
minute.) I actually did install a 50uf Radio Shack cap in my m105 and it
continues to work fine about a year after replacement. It's a tight fit, but it
can be done. (The fit in my broken cap m125's is a bit tighter and so far I've
not found a cap to fit, but have learned to live with the defect.) You will need
a Torx 5 (about US$5) to open the back. The cap looks like a watch battery on
legs and is on large solder pads so is not hard to unsolder and replace.
Good luck.

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> .22F (farads) is the same as 220uf (microfarads) which is the way
> most caps are labeled these days.

I think your decimal point needs to be moved a few places. A
microFarad is one millionth of a Farad, not one thousandth.

Greg

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On Tue, 16 Nov 2004 08:23:27 -0500, No Spam wrote:

> They say that the original is a 0.22Farads, this doesn't sound right.
> Is it really a .22 micro Farad?

If it really was 0.22 Farads it would most likely be a relatively
leaky electrolytic capacitor which would not be good for battery
life, not to mention that its size would, if truth in advertising is
a goal, suggest a name change from Palm M105 to Lap M105.  

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On Tue, 16 Nov 2004 18:26:37 GMT, Aaron L wrote:

> These were reported here as hard to find or purchase in single
> quantities. .22F (farads) is the same as 220uf (microfarads) which is the way
> most caps are labeled these days.

Are you sure about that? 0.22F is about 1/5 farads, and 220uf is
220/1,000,000 farads, (0.00220F) or about 1/500 farads, unless I've
forgotten the difference between milli, micro, pico, femto, etc.

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OK, folks, it really is 0.22 Farads. Not millifarads or microfarads.
It's not an aluminum electrolytic but a carbon double layer capacitor.

That said, they fail as opens. In other words, they become electrically
nonexistant. So you can just solder another capacitor in parallel with it
to make it work.

I found some 1 farad caps at the local surplus shop (HSC Electronics) for
about US$1 each that are rated at 5 volts (that's the harder part - most
are less than the necessary 3.3V). About 1" diameter and 0.1" thick, I
just added pigtails, glued it to the ROM and hooked the wires in parallel
with the existing capacitor. Has worked fine ever since. Better than
new, for that matter - if I dropped it when new, the battery cover would
often fly off and the batteries emerge. Reinstalling them gave the
dreaded news that memory had been lost. Now it is saved no matter what.

Not bad for a buck!

Jim Horn (EE for 29 years and counting)

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On Tue, 16 Nov 2004 21:59:14 -0000, James Horn wrote:

> OK, folks, it really is 0.22 Farads. Not millifarads or microfarads.
> It's not an aluminum electrolytic but a carbon double layer capacitor.

Amazing. I used to replace similar power supply capacitors that
were about the size of quart milk containers.


> That said, they fail as opens. In other words, they become electrically
> nonexistant. So you can just solder another capacitor in parallel with it
> to make it work.

Do they always, usually or sometimes fail as opens? If the
original cap. is the appropriate type, I'd just snip it out of the
circuit and solder the new cap. to the remaining leads.


> I found some 1 farad caps at the local surplus shop (HSC Electronics) for
> about US$1 each that are rated at 5 volts (that's the harder part - most
> are less than the necessary 3.3V). About 1" diameter and 0.1" thick, I
> just added pigtails, glued it to the ROM and hooked the wires in parallel
> with the existing capacitor. Has worked fine ever since. Better than
> new, for that matter - if I dropped it when new, the battery cover would
> often fly off and the batteries emerge. Reinstalling them gave the
> dreaded news that memory had been lost. Now it is saved no matter what.

That still seems like a *huge* capacitor. What value cap. was
originally used in your PDA? I'd think that a farad sized capacitor
could just about power a Palm for a minute during the battery change
even while powered on!

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In article <1rllp0hq6j2p5cbl3bj6oqdkepb3kni904@4ax.com>,
BillB <alt.usenet.this.newsgroup> wrote:
> On Tue, 16 Nov 2004 21:59:14 -0000, James Horn wrote:

> > OK, folks, it really is 0.22 Farads. Not millifarads or microfarads.
> > It's not an aluminum electrolytic but a carbon double layer capacitor.

> Amazing. I used to replace similar power supply capacitors that
> were about the size of quart milk containers.

This type of capacitor is not suitable as a filter capacitor in a
power supply. Their internal impedance is so large that it can not
act as a filter capacitor and the current capability is not suitable.
They are perfect as a power backup in a PDA, Video or clock. For the
large power supplies you still need the "quart milk containers".

--
Göran Larsson http://www.mitt-eget.com/

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On Wed, 17 Nov 2004 10:58:47 GMT, Goran Larsson wrote:

>> Amazing. I used to replace similar power supply capacitors that
>> were about the size of quart milk containers.
>
> This type of capacitor is not suitable as a filter capacitor in a
> power supply. Their internal impedance is so large that it can not
> act as a filter capacitor and the current capability is not suitable.
> They are perfect as a power backup in a PDA, Video or clock. For the
> large power supplies you still need the "quart milk containers".

That's exactly what the large capacitors were used for, large
power supplies. At the time they were used, PDAs didn't yet exist.
For that matter personal computers didn't either as most people know
it. Various 8080 CPU compters were sold in kit form and you could
buy and assemble an Apple I computer (the Apple II was not quite
ready). I'm well aware of the internal impedance of those old
electrolyitics, and in the power supplies they were used in, 4 were
used in parallel and provided up to about 20 amps of DC current.
They lasted long enough (4 or 5 years) but due to their impedance
and slight resultant heating, wouldn't be expected to last much more
than that.

I'm not sure what you mean by 'filter' but that may be because you
seem to be referring to a different type of capacitor that the one
that I mentioned. The large capacitors were indeed used to convert
60 hz AC to DC which is a gross form of filtering but I didn't call
them filter capacitors. I just said that they were used in power
supplies. And they weren't the type of capacitor used to filter out
the remaining voltage 'ripple'. Smaller, higher quality capacitors
were used for that purpose.

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In article <4edmp0plf4k0mlr612vgkneablcc6cp8b1@4ax.com>,
BillB <alt.usenet.this.newsgroup> wrote:

> That's exactly what the large capacitors were used for, large
> power supplies. At the time they were used, PDAs didn't yet exist.

Large capacitors are still used in large power supplies. The type
of capacitors used in the M105 is in no way replacing the large
capacitors.

> They lasted long enough (4 or 5 years) but due to their impedance
> and slight resultant heating, wouldn't be expected to last much more
> than that.

The impedance of the large power supply capacitors is nothing compared
to the impedance of the small 0.22F capacitor used in the M105. The
impedance is so high that they are completely worthless as a power
supply filter capacitor. Their intended application is to replace
backup batteries in low current applications like a PDA, video or clock.

> I'm not sure what you mean by 'filter' but that may be because you
> seem to be referring to a different type of capacitor that the one
> that I mentioned.

Big electrolytic capacitors are almost always used as filter capacitors
in power supplies.

> The large capacitors were indeed used to convert
> 60 hz AC to DC which is a gross form of filtering but I didn't call
> them filter capacitors.

You don't use capacitors to convert 60Hz AC to DC. The 60Hz AC is
converted to a pulsating DC using a rectifier (diodes). The pulsating
DC is smoothed to a nice DC using filter capacitors (big electrolytic
capacitors).

> I just said that they were used in power
> supplies. And they weren't the type of capacitor used to filter out
> the remaining voltage 'ripple'. Smaller, higher quality capacitors
> were used for that purpose.

You can't use a small capacitor to filter out the ripples in a large
power supply.

--
Göran Larsson http://www.mitt-eget.com/

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On Wed, 17 Nov 2004 13:47:59 GMT, Goran Larsson wrote:

> Large capacitors are still used in large power supplies. The type
> of capacitors used in the M105 is in no way replacing the large
> capacitors.

Of course. If you felt the need to say this you must have
misinterpreted something I wrote.



> You don't use capacitors to convert 60Hz AC to DC. The 60Hz AC is
> converted to a pulsating DC using a rectifier (diodes). The pulsating
> DC is smoothed to a nice DC using filter capacitors (big electrolytic
> capacitors).

Of course, again. I've designed (relatively simple) power
supplies, usually using 4 diodes in a bridge design. If I wanted to
pick the kind of nits you're looking for I could just as easily say
that you can't convert AC to DC using capacitors and diodes, because
they need wires to connect them.


> You can't use a small capacitor to filter out the ripples in a large
> power supply.

Of course not. The best EEs accomplish that with dessicated,
sputtered-metal coated lutefisk.

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Here in comp.sys.palmtops.pilot,
AaronJ <noemail@noemail.com> spake unto us, saying:

>-Hotsync before and after (less than 5 minutes).

I have a 8MB Northstar Memorysafe module for my m105:

http://www.northstarmobile.com/

My m105's capacitor is dead, but this makes a battery change relatively
painless. All I have to do is restore the MemorySafe software from the
PC or from my wife's m100, and the pull the rest from the flash module.

--
-Rich Steiner >>>---> http://www.visi.com/~rsteiner >>>---> Smyrna, GA USA
OS/2 + eCS + Linux + Win95 + DOS + PC/GEOS + Executor = PC Hobbyist Heaven!
WARNING: I've seen FIELDATA FORTRAN V and I know how to use it!
The Theorem Theorem: If If, Then Then.

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"Aaron L" <noemail@noemail.com> wrote in message
news:begkp0958h72e5ki8vm3oqqh0u80atn5bs@4ax.com...
> >
> >I've seen several articles on replacing the capacitor in Palm M105s...
>
> The actual part is a Dynacap double layer capacitor made by Elna in
> the USA. This is a 3.3v .22F unit with Elna part number DSK-3R3H224-H.
> These were reported here as hard to find or purchase in single
> quantities.

I give up - I can't seem to find one of these anywhere in the UK. The wiz
at Maplins tells me an ordinary capacitor with a similar rating like
http://www.maplin.co.uk/Module.aspx?ModuleNo=456&TabID=...
simply won't do the job, despite what the catalogue says.

Does anyone know of a source of the Elna unit or suggest a suitable
alternative?

TIA,
R.

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Rudy Lacchin wrote:
>
> "Aaron L" <noemail@noemail.com> wrote in message
> news:begkp0958h72e5ki8vm3oqqh0u80atn5bs@4ax.com...
> > >
> > >I've seen several articles on replacing the capacitor in Palm M105s...
> >
> > The actual part is a Dynacap double layer capacitor made by Elna in
> > the USA. This is a 3.3v .22F unit with Elna part number DSK-3R3H224-H.
> > These were reported here as hard to find or purchase in single
> > quantities.
>
> I give up - I can't seem to find one of these anywhere in the UK. The wiz
> at Maplins tells me an ordinary capacitor with a similar rating like
> http://www.maplin.co.uk/Module.aspx?ModuleNo=456&TabID=...
> simply won't do the job, despite what the catalogue says.
>
> Does anyone know of a source of the Elna unit or suggest a suitable
> alternative?

I have no idea why the 5.5V 0.22F cap you showed wouldn't work, but I'd
suspect it is going to be somewhat larger than the 3.3V version, which
might present a problem inside the limited space available in a PDA.

Generally, a capacitor with a higher voltage rating is OK to substitute
for one with a lower voltage rating. If the Maplins cap fits, go ahead
and use it.

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"Rudy Lacchin" <rulaREMOVETHIS@blueyonder.co.uk> wrote:
>>This is a 3.3v .22F unit with Elna part number DSK-3R3H224-H.

>I give up - I can't seem to find one of these anywhere in the UK.

Would it really be wise to replace your failed cap with an 'original type' part?
It appears that virtually all of these caps eventually fail after a few years
(or less). Even those who bought replacement boards to fix this problem had the
caps on them again fail. All my four m1xx units are now failed. If you can't
find your cap, or if you change your mind, you might try one of several
workarounds:

-Hotsync before and after (less than 5 minutes).
-Backup to a card (less than 2 minutes-m125 only).
-Replace with different type of cap (size is the problem).
-Use rechargeable batteries and charge them *in* the unit.
-Use an external battery pack to hold the voltage during change.
-Find an old IIIxx model and rob it. These caps don't seem to fail as much.

I've tried them all, but in the end I think that hotsyncing for the m100/m105
and backup to the card for the m125 turned out to be the easiest. And really,
when you only have to change the batteries once a month or so, it's not all that
big an inconvenience anyway...

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Here in comp.sys.palmtops.pilot,
AaronJ <noemail@noemail.com> spake unto us, saying:

>rsteiner@visi.com (Richard Steiner) wrote:
>
>>I have a 8MB Northstar Memorysafe module for my m105:
>
>I have one of those. I never used it on my m100 or m105 because they
>don't have flash rom.

Ah. Then it seems I've found value where you have not. :-)

>If I lost all my data, I also lost the Northstar module backup program
>and without that I couldn't reload from the module so was SOL.

True, but that module can be restored by beaming it back from any Palm
device (no PC required), or by restoring that single file from the PC.

Given the low price for m105's currently on eBay (I just bought another
one complete with a PalmPix camers and 8MB Northstar module for US$40),
it's almost worthwhile to buy a second one simply for backup purposes.

>>All I have to do is restore the MemorySafe software from the PC
>
>If you're going to use a PC to restore the MemorySafe software anyway,
>why not just do a regular hotsync to restore everything?

I still use a serial cradle for several reasons. A complete restoral
of 8MB takes quite some time, and ties the Palm to that location.

By using the Northstar, I can restore one file, then take the Palm with
me while the MemorySafe data restoral is taking place.

>That's quicker and easier.

Not so. The restoral from the flash device is actually slightly faster
(in my case) than the transfer from the PC, and it doesn't tie me to a
single location.

>>or from my wife's m100, and the pull the rest from the flash module.
>
>Her cap is still good???  

Doesn't matter. Since even a set of NiMH AAA's last each of us roughly
three weeks given our usage patterns, the chances of both Palms dying
at the same time are extremely small.

--
-Rich Steiner >>>---> http://www.visi.com/~rsteiner >>>---> Smyrna, GA USA
OS/2 + eCS + Linux + Win95 + DOS + PC/GEOS + Executor = PC Hobbyist Heaven!
WARNING: I've seen FIELDATA FORTRAN V and I know how to use it!
The Theorem Theorem: If If, Then Then.

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rsteiner@visi.com (Richard Steiner) wrote:

>I have a 8MB Northstar Memorysafe module for my m105:

I have one of those. I never used it on my m100 or m105 because they don't have
flash rom. If I lost all my data, I also lost the Northstar module backup
program and without that I couldn't reload from the module so was SOL.

I did use it on my IIIxe though and it worked fine. The IIIxe does have flash
rom where the Northstar program can be loaded so that it will survive a hard
reset/complete data loss. But my IIIxe's backup cap is still working just fine
and I've never needed to use the module for a complete recovery. But then I
guess that's nothing to complain about and the module did give me some piece of
mind on trips.

>All I have to do is restore the MemorySafe software from the PC

If you're going to use a PC to restore the MemorySafe software anyway, why not
just do a regular hotsync to restore everything? That's quicker and easier.

>or from my wife's m100, and the pull the rest from the flash module.

Her cap is still good???  

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On Sun, 19 Dec 2004 01:28:40 -0500, Richard Steiner wrote:

> >Her cap is still good???  
>
> Doesn't matter. Since even a set of NiMH AAA's last each of us roughly
> three weeks given our usage patterns, the chances of both Palms dying
> at the same time are extremely small.

A bit of case surgery might allow you to add a connector which
would allow the NiMH's to be recharged while inside the M105. If
there are any existing but unused traces on the hotsync connector,
they could be used instead, avoiding having to drill out the case
and not needing to find room to fit a socket within the M105.
Looking inside my hotsync cradle, it appears that of the 10 traces
on the connector, the middle 4 aren't used.

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rsteiner@visi.com (Richard Steiner) wrote:

>AaronJ <noemail@noemail.com> spake unto us, saying:

>>>or from my wife's m100, and the pull the rest from the flash module.
>>
>>Her cap is still good???  
>
>Doesn't matter. Since even a set of NiMH AAA's last each of us roughly
>three weeks given our usage patterns, the chances of both Palms dying
>at the same time are extremely small.

But what happens if you have one of those fatal errors that require a hard reset
and you wife's not around? So you try and call her to hurry and bring over her
m100 to beam you that needed backup program, but your cell phone's dead. Damn.
But hey there's a pay phone right over there and you're able to get her. Great.
And she's not far away so she's there in ten minutes. But oops, it just happens
that today you forgot to carry your little Northstar module with you. Damn. Ok,
back to the house...

Maybe it's time to treat you and your wife to a couple of Zire 21's (US$99) for
Xmas...  

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On Sun, 19 Dec 2004 18:09:11 GMT in comp.sys.palmtops.pilot,
AaronJ <noemail@noemail.com> spake unto us, saying:

> rsteiner@visi.com (Richard Steiner) wrote:
>
>>Doesn't matter. Since even a set of NiMH AAA's last each of us roughly
>>three weeks given our usage patterns, the chances of both Palms dying
>>at the same time are extremely small.
>
> But what happens if you have one of those fatal errors that require
> a hard reset and you wife's not around?

Hmmm. That would be an interesting scenario. However, the only errors
that I've ever encountered on my m105 device were fixable with a soft
reset. No software loss involved.

I also have a pair of Northstar modules - one permanently in the house,
the other permanently in my briefcase. No "remembering" necessary. :-)

> Maybe it's time to treat you and your wife to a couple of Zire 21's
> (US$99) for Xmas...  

What would they give me over the m105 that I would actually use?

From the specs I've seen, that strikes me as a waste of money...

--
-Rich Steiner >>>---> http://www.visi.com/~rsteiner >>>---> Smyrna, GA USA
OS/2 + eCS + Linux + Win95 + DOS + PC/GEOS + Executor = PC Hobbyist Heaven!
Applications analyst/designer/developer (14 yrs) seeking employment.
See web site above for resume/CV and background.

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On Sun, 19 Dec 2004 12:14:57 GMT in comp.sys.palmtops.pilot,
BillB <rainbose@earthlink.newt> spake unto us, saying:

> A bit of case surgery might allow you to add a connector which
> would allow the NiMH's to be recharged while inside the M105.

The lack of a capacitor bothers me so little that it isn't worth it to
tinker. If it becomes an issue, I'll simply buy another unit on eBay.

--
-Rich Steiner >>>---> http://www.visi.com/~rsteiner >>>---> Smyrna, GA USA
OS/2 + eCS + Linux + Win95 + DOS + PC/GEOS + Executor = PC Hobbyist Heaven!
Applications analyst/designer/developer (14 yrs) seeking employment.
See web site above for resume/CV and background.