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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Would you change this cap ?
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 |
#3
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Would you change this cap ?
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" wrote in message om... 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 |
#4
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Would you change this cap ?
In message , Bill
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 |
#5
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Would you change this cap ?
Dr. Anton Squeegee 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 |
#6
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Would you change this cap ?
On Sat, 6 Dec 2003 08:46:12 -0800, Dr. Anton Squeegee
wrote: In article , 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. |
#7
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Would you change this cap ?
Use an ESR meter. Even a fantastic quality mutimeter will regularly check caps
as good when in fact they are bad. Ron |
#8
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Would you change this cap ?
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" wrote in message om... 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 |
#9
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Would you change this cap ?
"Jerry G." bravely wrote to "All" (07 Dec 03 01:19:04)
--- on the heady topic of " Would you change this cap ?" +20%?!?! You mean more like +100%!!! -10/+20% is more like a precision electro... ;-) JG From: "Jerry G." 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" wrote in message JG om... 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... |
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