Replace bad caps with Panasonic caps

[liukuohao]

Re: Replace bad caps with Panasonic caps

Yes, that is an excellent replacement. I don't know why I couldn't find it when I made the search.

Ok, then can you vouch that there is no problem with the motherboard
stability in the long term usage?

In my preference, I like the polymer/ solid capacitor better than the standard
electrolytic ones

[liukuohao]

Re: Replace bad caps with Panasonic caps

ESR is a characteristic and Impedance is another thing.

However, when capacitors are used on motherboards or power supplies in a specific way (high frequency switching power supplies or voltage regulators for CPU or RAM for example), the impedance value is almost the same as the ESR value. So, it's safe to consider the Impedance value listed in the datasheet (the one measured at 100kHz) as ESR.

The ESR should be as close as possible to the capacitors you replace. It's acceptable to be a bit below or a bit above (let's say 10-20%) but if the value is much different there can be problems (motherboard acting up, instability, premature death of capacitors etc).
So if your old capacitors had about 30 mOhm ESR and these new ones have 9 mOhm, there is a small risk, they're not quite a good match.

Those KZG capacitors probably had about 30 mOhm when they came out of the factory, but as they aged and started to go bad, the value changed (usually increases).

Before the motherboard started to show signs of problems, the capacitors probably had much higher ESR for months but the circuits on the motherboard tolerated that and still worked OK. So there is a bit of room when choosing replacement capacitors.

Q3) I have recently bought a desoldering gun workstation.
What is the right temperature to have gun heat up. What is the Celsius ????

The temperature depends on what you want to desolder and where it's installed. Solder melts at 180-220 degrees Celsius, depending on what type of solder it's used.
However, when you put the gun on solder, the solder and the copper in the circuit board where the component is installed will pull heat away from the gun so the gun tip will cool down. That's why it's normal to configure the temperature higher than 220-250c, usually 300-320C is a normal temperature.

Basically, you want to keep temperature low because you don't want to damage components or the circuit board but at the same time, it has to be high enough to actually start melting the solder.

Motherboards have large surfaces of copper in the circuit board, they will act as a heatsink and it could be a bit harder to use a gun on them. You may need to increase the temperature.
Another tip ... add a bit of solder to the leads of the capacitors that are already soldered, then use the desoldering gun if needed.

Learn how to use the desoldering gun, search youtube for videos that show how to use it.

Thank for your informative advice.
But I am getting conflicting advices from the forum members.
As you are advising me to stick to a capacitor that can MATCH the previous
capacitor's ESR value as CLOSE as possible. Yet I am hearing others that get
a LOW ESR will work fine provided you are getting a same capacitance of
820uf, 6.3v(or higher 10v). Sigh..... which side do I follow??

[c_hegge]

Re: Replace bad caps with Panasonic caps

^
It's listed as a tantalum capacitor. It should really have been listed as an electrolytic (like most of the other polies on RS).

[mockingbird]

Re: Replace bad caps with Panasonic caps

Q2) Does this Nichicon polymer / solid capacitor works on my capacitor
replacement:
http://my.rs-online.com/web/p/tantal...itors/0541491/?
I saw the the ESR value is very low = 0.009 ohms but it does not match the
UCC KZG series capacitor

Yes, that is an excellent replacement. I don't know why I couldn't find it when I made the search.

[mariushm]

Re: Replace bad caps with Panasonic caps

ESR is a characteristic and Impedance is another thing.

However, when capacitors are used on motherboards or power supplies in a specific way (high frequency switching power supplies or voltage regulators for CPU or RAM for example), the impedance value is almost the same as the ESR value. So, it's safe to consider the Impedance value listed in the datasheet (the one measured at 100kHz) as ESR.

The ESR should be as close as possible to the capacitors you replace. It's acceptable to be a bit below or a bit above (let's say 10-20%) but if the value is much different there can be problems (motherboard acting up, instability, premature death of capacitors etc).
So if your old capacitors had about 30 mOhm ESR and these new ones have 9 mOhm, there is a small risk, they're not quite a good match.

Those KZG capacitors probably had about 30 mOhm when they came out of the factory, but as they aged and started to go bad, the value changed (usually increases).

Before the motherboard started to show signs of problems, the capacitors probably had much higher ESR for months but the circuits on the motherboard tolerated that and still worked OK. So there is a bit of room when choosing replacement capacitors.

Q3) I have recently bought a desoldering gun workstation.
What is the right temperature to have gun heat up. What is the Celsius ????

The temperature depends on what you want to desolder and where it's installed. Solder melts at 180-220 degrees Celsius, depending on what type of solder it's used.
However, when you put the gun on solder, the solder and the copper in the circuit board where the component is installed will pull heat away from the gun so the gun tip will cool down. That's why it's normal to configure the temperature higher than 220-250c, usually 300-320C is a normal temperature.

Basically, you want to keep temperature low because you don't want to damage components or the circuit board but at the same time, it has to be high enough to actually start melting the solder.

Motherboards have large surfaces of copper in the circuit board, they will act as a heatsink and it could be a bit harder to use a gun on them. You may need to increase the temperature.
Another tip ... add a bit of solder to the leads of the capacitors that are already soldered, then use the desoldering gun if needed.

Learn how to use the desoldering gun, search youtube for videos that show how to use it.

[liukuohao]

Re: Replace bad caps with Panasonic caps

Hi All!

Thank you very much for your advice!!

Q1) Why does it necessary to match the ESR /impedance value of a
capacitor which I am about to replace?

Q2) Does this Nichicon polymer / solid capacitor works on my capacitor
replacement:
http://my.rs-online.com/web/p/tantal...itors/0541491/?
I saw the the ESR value is very low = 0.009 ohms but it does not match the
UCC KZG series capacitor

Q3) I have recently bought a desoldering gun workstation.
What is the right temperature to have gun heat up. What is the Celsius ????

[mockingbird]

Re: Replace bad caps with Panasonic caps

In my opinion, this is the only suitable replacement:

http://my.rs-online.com/web/p/alumin...itors/7083642/

It matches KZG ESR of 0.030, but it is 8x20mm instead of 8x11.5, so you will have to account for the extra height.

[c_hegge]

Re: Replace bad caps with Panasonic caps

^
That's what I would do. I have a few Nichicon L8 (or S8, can't remember for sure which) 820uF 6.3V in 8mm dia. It doesn't look as though RS has them, so you could try element14. The ESR there is only 7 or 8 mOhm.

You could also use 820uF 16V to get the ESR down a bit.

[stj]

Re: Replace bad caps with Panasonic caps

or use poly's

[mariushm]

Re: Replace bad caps with Panasonic caps

The ESR of the capacitor is specified in the datasheet, which you can find here:

The ESR is a bit high compared to the ESR of the KZG series, you should use capacitors with a bit lower ESR even if the lifetime rating is not as high.

You can get a lower esr by using a capacitor that's rated for higher voltage and/or for slightly higher capacitance. There is a relation between the volume of a capacitor and the ESR (among many other things) and as a capacitor rated for higher voltage will usually be slightly taller, that also means the ESR will be a bit lower.

So for example, while 820uF 6.3v Panasonic FR is advertised as having 56mOhm ESR, an 1200uF 6.3v or a 1000uF 10v Panasonic FR capacitor will have an esr of about 41mOhm, which brings the ESR much closer to 36mOhm (the one KZG has).
Panasonic FM series should behave about the same, maybe even a bit lower ESR, but the lifetime is probably a bit smaller. 1200uF 6.3v and 1000uF 10v have 30 mOhm esr but they're 20mm tall (if there's heatsinks, coolers close by, make sure the height isn't a problem)

Now, 1000uF is close enough to 820uF that the circuit will be fine (95% sure), 1200 uF is a bit of a stretch but it may work just fine.

So now you can just go on RS-Online and pick the ones that are 8mm in diameter, because these capacitors are available in both 8mm and 10mm diameters.

Panasonic FM 1000uF 10v 8 x 20mm : http://my.rs-online.com/web/p/alumin...itors/5261115/
Panasonic FR 1000uF 10v 8 x 15 mm : http://my.rs-online.com/web/p/alumin...itors/7083548/

This should also work (just a bit weaker than Panasonic FR performance wise) :

Rubycon ZL 1000uF 10v 8 x 20mm : http://my.rs-online.com/web/p/alumin...itors/7037239/

[ReeceyBurger123]

Re: Replace bad caps with Panasonic caps

Try using rubycon mbz, or mcz they are great for motherboards and correct esr I use them in most of my repairs. If you cant find then have a look at nichicon hm, hz they are also motherboard grade.

[ReeceyBurger123]

Re: Replace bad caps with Panasonic caps

Fr isnt the correct esr for motherboards unfortunately.

[liukuohao]

Hi there,

I have some Chemi-con KZG 820uf 6.3v 8mm diameter are leaking badly.

I wonder if I replace the following Panasonic cap:
http://my.rs-online.com/web/p/alumin...itors/7083447/
would pose any problem later on my motherboard.

The reason, I choose this FR series capacitors because the endurance is
longer than the others = 10,000hrs!!!!

But it does not specified the ESR value???

Thank you for any guidance / feeback given.