Would you change this cap ?

[Bill]

Hi folks- If an electrolytic measures slightly over it's rated value
with a trusted meter, would you consider this cap bad thus replace it
? For example, if a 100uf measures 107uf, does that mean the cap is
drying out and must be replaced ? Thanks

Bill

 

[Dr. Anton Squeegee]

In article <8fb59540.0312060715.59afb535@posting.google.com>,
elect21st@aol.com says...

Hi folks- If an electrolytic measures slightly over it's rated value
with a trusted meter, would you consider this cap bad thus replace it
? For example, if a 100uf measures 107uf, does that mean the cap is
drying out and must be replaced ? Thanks

Not at all. Most electrolytics have a tolerance of at least 20%.
This means that 107uf is well within spec for a 100uf cap.

In any case, the electrolyte drying out would have the opposite
effect from what you're describing: Capacitance would, in that event,
decrease.


--
Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
kyrrin a/t bluefeathertech d-o=t c&o&m
Motorola Radio Programming & Service Available -
http://www.bluefeathertech.com/rf.html
"Quando Omni Flunkus Moritati" (Red Green)

 

[Leonard Caillouet]

If you suspect the cap may be bad and you don't have the equipment to test
it for ESR, DA, and leakage, or if there is any evidence of electrolyte
leakage, change it. 100uF caps are pretty cheap and easy to find.

The capacitance is well within tolerance, but there are other
characteristics that could be off.

Try http://my.execpc.com/~endlr/index.html for some good info on capacitors.

Leonard Caillouet

"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0312060715.59afb535@posting.google.com...

Hi folks- If an electrolytic measures slightly over it's rated value
with a trusted meter, would you consider this cap bad thus replace it
? For example, if a 100uf measures 107uf, does that mean the cap is
drying out and must be replaced ? Thanks

Bill

 

[Clint Sharp]

In message <8fb59540.0312060715.59afb535@posting.google.com>, Bill
<elect21st@aol.com> writes

Hi folks- If an electrolytic measures slightly over it's rated value
with a trusted meter, would you consider this cap bad thus replace it
? For example, if a 100uf measures 107uf, does that mean the cap is
drying out and must be replaced ? Thanks

Bill
Unless the cap is something really special I wouldn't suspect it of

being faulty for being more than its marked value, the tolerance on
electrolytics is usually greater than 10% anyway. On the other hand, if
the cap has been removed and is a standard part, I'd replace it anyway
if I had one in the parts drawer, purely because the action of heating
up the leads twice (once out, once in) is not wonderful for the part,
it's a dirt cheap part at that.
--
Clint

 

[Bob Parker]

Dr. Anton Squeegee <SpammersAreVermin@Dev.Null> wrote:

Not at all. Most electrolytics have a tolerance of at least 20%.
This means that 107uf is well within spec for a 100uf cap.

A lot of electrolytics have a tolerance of +50/-20%, as far as I know.
So +7% is entirely within that range.

Bob

 

On Sat, 6 Dec 2003 08:46:12 -0800, Dr. Anton Squeegee
<SpammersAreVermin@Dev.Null> wrote:

In article <8fb59540.0312060715.59afb535@posting.google.com>,
elect21st@aol.com says...

Hi folks- If an electrolytic measures slightly over it's rated value
with a trusted meter, would you consider this cap bad thus replace it
? For example, if a 100uf measures 107uf, does that mean the cap is
drying out and must be replaced ? Thanks

Not at all. Most electrolytics have a tolerance of at least 20%.
This means that 107uf is well within spec for a 100uf cap.

Plus, most cheap multimeters or only about %10 tolerance on their
measurements.

 

[RonKZ650]

Use an ESR meter. Even a fantastic quality mutimeter will regularly check caps
as good when in fact they are bad.
Ron

 

[Jerry G.]

Standard electrolytic caps, unless specified as precision, have a tolerance
of about -10% to about +20% of their nominal cap value. If you are using a
low cost cap meter, there may also be a 10% error to start with. The ESR
rating of the cap is also very important. As the cap ages, the ESR will go
up, and the cap value may decrease. In some cases the cap may start to go
resistive, or shorted.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0312060715.59afb535@posting.google.com...
Hi folks- If an electrolytic measures slightly over it's rated value
with a trusted meter, would you consider this cap bad thus replace it
? For example, if a 100uf measures 107uf, does that mean the cap is
drying out and must be replaced ? Thanks

Bill

 

[Asimov]

"Jerry G." bravely wrote to "All" (07 Dec 03 01:19:04)
--- on the heady topic of "Re: Would you change this cap ?"

+20%?!?! You mean more like +100%!!! -10/+20% is more like a precision
electro... ;-)

JG> From: "Jerry G." <jerryg50@hotmail.com>

JG> Standard electrolytic caps, unless specified as precision, have a
JG> tolerance of about -10% to about +20% of their nominal cap value. If
JG> you are using a low cost cap meter, there may also be a 10% error to
JG> start with. The ESR rating of the cap is also very important. As the
JG> cap ages, the ESR will go up, and the cap value may decrease. In some
JG> cases the cap may start to go resistive, or shorted.

JG> --

JG> Greetings,

JG> Jerry Greenberg GLG Technologies GLG
JG> =========================================
JG> WebPage http://www.zoom-one.com
JG> Electronics http://www.zoom-one.com/electron.htm
JG> =========================================


JG> "Bill" <elect21st@aol.com> wrote in message
JG> news:8fb59540.0312060715.59afb535@posting.google.com...
JG> Hi folks- If an electrolytic measures slightly over it's rated value
JG> with a trusted meter, would you consider this cap bad thus replace it
JG> ? For example, if a 100uf measures 107uf, does that mean the cap is
JG> drying out and must be replaced ? Thanks

JG> Bill

.... Is reactance then illusory? No, it just appears that way...