2007 Dell XPS 410/9200 with Bad Caps

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

The best you can get in electrolytic at 3300uF is Panasonic FS around 20mOhm ESR, almost twice the originals...
If you go for Polymer caps you have to check the voltages: because you might not be able to find them with ratings matching the originals.
But at least they will be able to match or exceed the ESR of the originals.
Things change in 11 years, what was sound advice then no longer is due to production advancements.
See this thread for example: https://www.badcaps.net/forum/showthread.php?t=65732

So if I am understanding your post properly, when sourcing poly caps the microfarad and ESR specs are critical, and slightly higher voltage rated polys with similar ripple current ratings would be ok?

Should I only replace the burst caps, or will I have to replace all the electrolytics with polys for things to work ok?

[Per Hansson]

Re: 2007 Dell XPS 410/9200 with Bad Caps

So my best advice is always replace all caps of a series that has failed, it is just common sense...
But if you wanna save a bit on cost (and in the end may or may not need to redo it) you could just replace all of the caps with the same rating.
So in your case it would be all 3300uF 6.3v KZG caps and 2200uF 6.3v Rubycon caps that I can't see the series of but I'm guessing their are MCZ.

The most important spec in a switching circuit like this is the ESR, and in the past (11 years ago) solid polymer caps with high capacitance ratings did not exist.
So the normal thing was to just halve the capacitance rating of the replacement caps and it would usually work.
Though a board specifically like this one you have here might not take great to that, and besides today higher capacitance caps are available so it is just common sense to utilize them...
As for the voltage rating that is where you would still have a problem today.
But normally these types of caps are used for memory and CPU voltage.
So they usually don't see anywhere near their rated voltages.
So you can go down in voltage rating, but you of course need to measure the voltages before to confirm what is safe (again some common sense here helps.)

[piernov]

Re: 2007 Dell XPS 410/9200 with Bad Caps

Issue is that ESR is so low on (most) solid polymer caps that sometimes the buck converter cannot regulate properly. For example inrush current can become a problem and soft-start doesn't work good enough, or regulator can oscillate. Using 1.5x less capacitance helps since the ESR will be slightly higher (smaller caps have higher ESR) and charging the caps take less time. Having less capacitance isn't really a problem, originally electrolytic caps with large capacitance are often used for their lower ESR than their high capacitance (and putting multiple ones in parallel divide the ESR as well).

That said, in most cases you can use different specs, not too far off, and it's fine. I don't have all the cap specs on hand, but with a few different Rubycon ZLH and some random solid polymer, sometimes even MLCC, I don't have issues recapping random boards. As long as it's not a random bag of general purpose caps from Aliexpress…

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

So my best advice is always replace all caps of a series that has failed, it is just common sense...
But if you wanna save a bit on cost (and in the end may or may not need to redo it) you could just replace all of the caps with the same rating.
So in your case it would be all 3300uF 6.3v KZG caps and 2200uF 6.3v Rubycon caps that I can't see the series of but I'm guessing their are MCZ.

The most important spec in a switching circuit like this is the ESR, and in the past (11 years ago) solid polymer caps with high capacitance ratings did not exist.
So the normal thing was to just halve the capacitance rating of the replacement caps and it would usually work.
Though a board specifically like this one you have here might not take great to that, and besides today higher capacitance caps are available so it is just common sense to utilize them...
As for the voltage rating that is where you would still have a problem today.
But normally these types of caps are used for memory and CPU voltage.
So they usually don't see anywhere near their rated voltages.
So you can go down in voltage rating, but you of course need to measure the voltages before to confirm what is safe (again some common sense here helps.)

Issue is that ESR is so low on (most) solid polymer caps that sometimes the buck converter cannot regulate properly. For example inrush current can become a problem and soft-start doesn't work good enough, or regulator can oscillate. Using 1.5x less capacitance helps since the ESR will be slightly higher (smaller caps have higher ESR) and charging the caps take less time. Having less capacitance isn't really a problem, originally electrolytic caps with large capacitance are often used for their lower ESR than their high capacitance (and putting multiple ones in parallel divide the ESR as well).

That said, in most cases you can use different specs, not too far off, and it's fine. I don't have all the cap specs on hand, but with a few different Rubycon ZLH and some random solid polymer, sometimes even MLCC, I don't have issues recapping random boards. As long as it's not a random bag of general purpose caps from Aliexpress…

Ok, here's what I think I've come up with for aluminum polymer replacement caps for my blown KZG and MCZ electrolytics:

First, specs for the originals

KZG: size 10X25mm, 6.3v, 3,300uF, 0.012 ESR, 2,550 Ripple. Datasheet: https://www.digikey.at/htmldatasheet...zg-series.html

MCZ: size 10X20mm, 6.3v, 2,200uF, 11mohms ESR, 2770mA Ripple. Datasheet: https://pdf1.alldatasheet.com/datash...BYCON/MCZ.html

Proposed KZG replacements: https://www.digikey.com/en/products/...C1500M/4204197

Proposed MCZ replacements: https://www.digikey.com/en/products/...MDN1PX/2239224

So do you think these will work, or am I going back to the drawing board?

[Per Hansson]

Re: 2007 Dell XPS 410/9200 with Bad Caps

I would go with the PSG I mentioned, it is available up to 2200uF at 16v at Digikey:
https://www.digikey.com/en/products/...2MJ20S/5824538

You could also go for this Kemet, it is a little bit cheaper:
https://www.digikey.com/en/products/...AE010/13420077

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

I would go with the PSG I mentioned, it is available up to 2200uF at 16v at Digikey:
https://www.digikey.com/en/products/...2MJ20S/5824538

You could also go for this Kemet, it is a little bit cheaper:
https://www.digikey.com/en/products/...AE010/13420077

So are you suggesting I use either of these as a replacement for both the KZG and the MCZ?

Thanks!

[Per Hansson]

Re: 2007 Dell XPS 410/9200 with Bad Caps

Yes

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

Yes

Ok great, thank you for all of your help and insight. I really appreciate you hanging in there even with my inexperience and noob nature.

I think I have one more question; can you please tell me why it is you chose this particular capacitor for the job?

I'm thinking 16v because it's rated high enough to avoid over-volting the cap, and with it being an ESR of 8 it's close to, but does not exceed the ESR rating of the original cap? These are a guess, I could be totally wrong.

[Per Hansson]

Re: 2007 Dell XPS 410/9200 with Bad Caps

The lower the ESR the better, so this one is slightly better than the originals.
I choose 2200uF vs the 1500uF that you showed simply because they are closer to the originals values.
The voltage rating is just a coincidence: it is what is available in that size...

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

The lower the ESR the better, so this one is slightly better than the originals.
I choose 2200uF vs the 1500uF that you showed simply because they are closer to the originals values.
The voltage rating is just a coincidence: it is what is available in that size...

Thanks for the insight. This will help should I need to repeat the repair on something else. I have ordered the parts and will update the post as soon as I'm confident I have a winner, or if I happen to have any questions after the job is complete.

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

Issue is that ESR is so low on (most) solid polymer caps that sometimes the buck converter cannot regulate properly. For example inrush current can become a problem and soft-start doesn't work good enough, or regulator can oscillate. Using 1.5x less capacitance helps since the ESR will be slightly higher (smaller caps have higher ESR) and charging the caps take less time. Having less capacitance isn't really a problem, originally electrolytic caps with large capacitance are often used for their lower ESR than their high capacitance (and putting multiple ones in parallel divide the ESR as well).

That said, in most cases you can use different specs, not too far off, and it's fine. I don't have all the cap specs on hand, but with a few different Rubycon ZLH and some random solid polymer, sometimes even MLCC, I don't have issues recapping random boards. As long as it's not a random bag of general purpose caps from Aliexpress…

The lower the ESR the better, so this one is slightly better than the originals.
I choose 2200uF vs the 1500uF that you showed simply because they are closer to the originals values.
The voltage rating is just a coincidence: it is what is available in that size...

Ok so the caps made it here Saturday afternoon and I installed them right away. It was a pretty challenging install since I only have a 25w soldering iron (the tip on the 45w iron from the storage unit was bad). I had some difficulty clearing the solder from the lugs in the circuit board but managed to get them cleared out and the new caps installed. There were traces on the board near the lugs that were very small and looked easy to damage or burn through if I wasn't careful, but I managed not to goof any of them up.

As of now everything looks like it's working properly, and the operation was a success!

My sincere thanks to everyone who participated in this thread and helped me with the knowledge I needed to order the caps and get this done!

[Per Hansson]

Re: 2007 Dell XPS 410/9200 with Bad Caps

Thanks for getting back, I'm surprised you got that done with a 25w iron though!
It is not something I would recommend anyone try, too high risk to damage the board.
Just putting that here for anyone else following along...

P.S: This thread was cross posted with this other one here:
https://www.badcaps.net/forum/showthread.php?t=103263

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

Thanks for getting back, I'm surprised you got that done with a 25w iron though!
It is not something I would recommend anyone try, too high risk to damage the board.
Just putting that here for anyone else following along...

P.S: This thread was cross posted with this other one here:
https://www.badcaps.net/forum/showthread.php?t=103263

I completely agree, a 25w iron is not ideal for this job. It's too bad the 45w iron I found in the storage unit had a bad tip. If that's not bad enough tips aren't available for this iron anymore. All said I feel lucky to have a positive result.

[stj]

Re: 2007 Dell XPS 410/9200 with Bad Caps

what is the 45w iron?

[DXseekerMO]

Re: 2007 Dell XPS 410/9200 with Bad Caps

what is the 45w iron?

Craftsman model 113.540420