when (time frame) to just replace old electrolytic caps ?

[robb]

i am working on an old mid 80's circuit board that has some
original 2200 uF/ 63V electrolytic caps (size of a C-cell) plus
some others and was just wondering when one should just replace
such a creature ?

says made in W-Germany "Elkorauh" if it makes a diference ?

should i remove and test them (maybe stress them ?) or just leave
them alone (i.e. fix broken things)
is there a life expectancy for electrolytics ?

thanks for help,
robb

 

[Peter A Forbes]

i am working on an old mid 80's circuit board that has some
original 2200 uF/ 63V electrolytic caps (size of a C-cell) plus
some others and was just wondering when one should just replace
such a creature ?

says made in W-Germany "Elkorauh" if it makes a diference ?

should i remove and test them (maybe stress them ?) or just leave
them alone (i.e. fix broken things)
is there a life expectancy for electrolytics ?

thanks for help,
robb

We work on a shelf life of 10 years before needing reforming, assuming optimum
ambient temp etc etc.

In service on continuous operation about 20 years before we replace.

We do refurbs on our older 30V switch tripping batteries and chargers, and we
replace all the electrolytics and rectifiers, and the small transformer as well.
Most of these come in when the batteries are at end of life, usually 7 years or
so.

Bigger systems tend to be less of a problem as the caps are bigger and better
quality.

Our preferred vendor was Philips/BC Components, but we are now using Rifa/Evox
and BHC.

Peter

 

[Jamie]

i am working on an old mid 80's circuit board that has some
original 2200 uF/ 63V electrolytic caps (size of a C-cell) plus
some others and was just wondering when one should just replace
such a creature ?

says made in W-Germany "Elkorauh" if it makes a diference ?

should i remove and test them (maybe stress them ?) or just leave
them alone (i.e. fix broken things)
is there a life expectancy for electrolytics ?

thanks for help,
robb

Yes there is a life expectancy with electrolytics how ever, if you have
tested these caps after some reforming time and found them to be ok,
it may not be necessary to replace them..

One a second note:
If you're restoring, It might be a good idea to do so.

 

[Marra]

For the sake of reliability I would replace them after 5 years.

Its better to replace them than for them to pop and take something
else with them.

www.ckp-railways.talktalk.net/pcbcad28.htm

 

[[email protected]]

i am working on an old mid 80's circuit board that has some
original 2200 uF/ 63V electrolytic caps (size of a C-cell) plus
some others and was just wondering when one should just replace
such a creature ?

says made in W-Germany "Elkorauh" if it makes a diference ?

should i remove and test them (maybe stress them ?) or just leave
them alone (i.e. fix broken things)
is there a life expectancy for electrolytics ?

First off, "Elko" is short for "Elektrolytkondensator" (electrolytic
capacitor), and "rauh" ("rough") refers to the electrode type. This
kind of etched electrodes is standard; they result in higher
capacitance per volume, while plain electrodes mean better behavior at
high (i.e. upper audio) frequencies. And, generally speaking, you can
expect electrolytic capacitors from Germany to be of high quality
(i.e. to be comparatively long-lasting).

The life-time of electrolytic capacitors is primarily linked to
electrolyte loss (i.e. evaporation) over time, which strongly
correlates with ambient (storage or operating) temperature; it further
depends on the quality of the seal, and on the (initial) amount of
electrolyte they are meant to contain - larger capacitors can
therefore be better than miniaturized ones.

According to their expected use (e.g. consumer versus industrial
products, room temperature versus elevated temperatures), electrolytic
capacitors are sold in different "endurance classes" which can be
inferred from the labeling. The cheapest (consumer quality)
electrolytics are typically rated >2000 hours (three months) at 85
degrees centigrade. However, even this usually translates into >300000
hours (thirty years) at 30 degrees. And still significantly longer at
really convenient room temperatures. Industrial quality electrolytics
(rated >2000h at 105°) can be expected to last at least twice as long.

Thus, at normal ambient and operating temperatures, even standard
electrolytics can be expected to last a human life. Smoothing
capacitors in power supplies that are noticeably heated up by the
ripple currents they are expected to short-circuit, or by adjacent
transformers or heat sinks, are usually more endangered. Unless your
board is operated at elevated temperatures, or is safety-critical or
would be hard to service because it will be installed in an
inaccessible place, a prophylactic replacement after 20 years would
usually seem unnecessary.

Martin.

 

[Eeyore]

For the sake of reliability I would replace them after 5 years.

Good Lord ! I'd say that was very premature with 'typical' use.

Graham

 

[[email protected]]

Good Lord ! I'd say that was very premature with 'typical' use.

Indeed. It's all about evaporation and diffusion through the seal, and
you can't discuss this without discussing temperature. Electrolyte
loss more than doubles for each temperature rise of 10 degrees
centigrade. For specific numbers applying to a quality product of the
">2000 hours at 105 degree" type see

<http://www.epcos.com/inf/20/30/db/aec_07/B41851__B43851.pdf>.

If you extrapolate the diagram at the top of page 19 to lower
temperatures you easily arrive at life-times in excess of 100 years
(10^6 hours) for low ripple-current loads.

Martin.

 

[Pieter]

For the sake of reliability I would replace them after 5 years.

Its better to replace them than for them to pop and take something
else with them.

www.ckp-railways.talktalk.net/pcbcad28.htm

Hmm. 5 years?

I suggest:
if it is "made in China" every 3 months
if it is old Philips, and not used in high current or in a high
temperature environments: 50 years or so

I have several old radio's etc with original componnents from the 50's
and 60's that still work perfectly. Not using them is bad. Use them
and if they have not been used for years, format the caps at low
voltage/current.

Pieter

 

[Marra]

I run high power amplifiers that run quite hot so 5 years is a good
time.
I havent had any go short circuit yet so 5 years must be on the safe
side.

 

[robb]

We work on a shelf life of 10 years before needing reforming, assuming optimum
ambient temp etc etc.

In service on continuous operation about 20 years before we replace.

We do refurbs on our older 30V switch tripping batteries and chargers, and we
replace all the electrolytics and rectifiers, and the small transformer as well.
Most of these come in when the batteries are at end of life, usually 7 years or
so.

Bigger systems tend to be less of a problem as the caps are bigger and better
quality.

Our preferred vendor was Philips/BC Components, but we are now using Rifa/Evox
and BHC.

thanks Peter,
the application is fairly light duty sealed environment with low
temps and little crowding, low temps and i think total usage time
is pretty low with low strees to so i will probably just let them
go on

thanks again for reply
robb

 

[robb]

Yes there is a life expectancy with electrolytics how ever, if you have
tested these caps after some reforming time and found them to be ok,
it may not be necessary to replace them..

One a second note:
If you're restoring, It might be a good idea to do so.

thanks for help and reply Jamie,

now i need to go google reforming capacitor

thanks for help
robb

 

[robb]

replace
such a creature ?

First off, "Elko" is short for "Elektrolytkondensator" (electrolytic
capacitor), and "rauh" ("rough") refers to the electrode type. This
kind of etched electrodes is standard; they result in higher
capacitance per volume, while plain electrodes mean better behavior at
high (i.e. upper audio) frequencies. And, generally speaking, you can
expect electrolytic capacitors from Germany to be of high quality
(i.e. to be comparatively long-lasting).

The life-time of electrolytic capacitors is primarily linked to
electrolyte loss (i.e. evaporation) over time, which strongly
correlates with ambient (storage or operating) temperature; it further
depends on the quality of the seal, and on the (initial) amount of
electrolyte they are meant to contain - larger capacitors can
therefore be better than miniaturized ones.

According to their expected use (e.g. consumer versus industrial
products, room temperature versus elevated temperatures), electrolytic
capacitors are sold in different "endurance classes" which can be
inferred from the labeling. The cheapest (consumer quality)
electrolytics are typically rated >2000 hours (three months) at 85
degrees centigrade. However, even this usually translates into
300000
hours (thirty years) at 30 degrees. And still significantly longer at
really convenient room temperatures. Industrial quality electrolytics
(rated >2000h at 105°) can be expected to last at least twice as long.

Thus, at normal ambient and operating temperatures, even standard
electrolytics can be expected to last a human life. Smoothing
capacitors in power supplies that are noticeably heated up by the
ripple currents they are expected to short-circuit, or by adjacent
transformers or heat sinks, are usually more endangered. Unless your
board is operated at elevated temperatures, or is safety-critical or
would be hard to service because it will be installed in an
inaccessible place, a prophylactic replacement after 20 years would
usually seem unnecessary.

Martin.

Thanks Martin.

for all the useful info, now i can use your parameters to
determine if replacement is needed.
i think they will not need replacement because the stress level
( hours of usage, heat, etc..) is fairly low.

these appear to be used in a stepper motor circuit and are placed
far away from hot stuff

i was mostly concerned about deteriorating from just age alone,
but your info helps me relaize that capacitor age may not be as
important a factor on the 20 year scale

thanks again for all your helpful info,
robb

 

[robb]

Hmm. 5 years?

I suggest:
if it is "made in China" every 3 months
if it is old Philips, and not used in high current or in a high
temperature environments: 50 years or so

I have several old radio's etc with original componnents from the 50's
and 60's that still work perfectly. Not using them is bad. Use them
and if they have not been used for years, format the caps at low
voltage/current.

Pieter

thanks Pieter,
i think these have average to low use and probably can be left to
work for a few more years.

thanks again for help and reply,
robb