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Old 5th March 2010, 10:23 PM   #1
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Default Recap Krell KSA200S

Hi all,

I am disasembling my Krell KSA200S and recap all the electrolitics caps, except the bigs ones of the power supply.
There are four ERO and a few Sprague.
Anyone perfform this job, wihc brand is recomended for replace same or are others today that better the originals?

Thanks!
Rubén
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Old 5th March 2010, 10:53 PM   #2
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Default Recap!

Hi, I've done this before and the best brand (for my taste) is Panasonic and Rubycon.

Make sure you use the correct voltage and if possible a higher temp. cap 105 C.
You will probably notice that the new cap's are smaller that the old ones. Just try to fit a cap with a higher voltage than the old one, it'll fit just fine.

All the best,


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Old 5th March 2010, 11:08 PM   #3
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Hi Audiofanatic,

I see that there is in the main boards Sprague tantalum (grey color) axial leads, wich use for replace this?
Ok with the temperature rating and size

Thanks for your repply!
Rubén
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Old 5th March 2010, 11:54 PM   #4
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Default Pics!

Hi Rubén,

Please send us pic's of the component's you want to replace and I'll try to help you the best I can.

Regards,


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Old 6th March 2010, 01:47 AM   #5
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Hi Audiofanatic,

Here is the caps that I want to replace,
http://media.digikey.com/photos/Vish...107X9025F2.JPG
CAP WET TANT 560UF 10% 60V AXIAL - ST560-60T4KI

This is only to see wich kind od cap is, the voltage and capacitance is different.

Rubén
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Old 6th March 2010, 01:44 PM   #6
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It depends on the value of the cap.

If we're talking about 47 Uf/60 volts than you can use Rubicon axial that's OK.

But make a picture of the actual component and it's value than I'll give you a straight answer.

All the best,


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Old 6th March 2010, 03:53 PM   #7
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Hi Audiofanatic,

The caps are Sprague tantalum, the values are 47uf X 100V (Six per board) and 220uf X 25V (one per board)
They are placed in the ouput main board.
Do you said that replace this tantalum with electrolitics?

In the drive board are four ROE 470uf X 100V (gold colour)
I need to do a search to find if this ROE caps are electrolitics or tantalum.

Currently Iam working but latter take a few pictures.

Best Regards
Rubén
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Old 6th March 2010, 10:21 PM   #8
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Hi Audiofanatic,

Here is the link to some pictures, the small grey are the tantalum

ImageShack® - rds70's Profile Page

Do you know how appart the heatsinks from the main board, I take off all the screws buy cant release...

Best Regards
Rubén

Last edited by serraniruben; 6th March 2010 at 10:26 PM.
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Old 6th March 2010, 10:57 PM   #9
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I would not replace those tantalum's with electrolytic, the ESR is much higher. Really good Tantulum caps are really good, they are just expensive. There are few electrolytics that would compare.

The ROE's are electrolytics for sure. ROE makes great parts, and I would only replace with an equally good part.

As for brands, while Rubycon and Panasonic make really good caps, there is nothing wrong with Nichicon or Elna either, and if they have a part that works for your need, don't be afraid to use them. I highly recommend them for local supply caps, and like the Nichicon gold supply caps better than the CDE that Krell appears to have used.

Is there anything wrong with the ROE caps? Are you just replacing them because they are older? If there is nothing wrong with them, I don't know that I would bother. I would consider running some tests, make sure the noise and distortion figures are within test, nothing seems strongly out of spec, and leave it at that. If things are out of spec, or caps are measuring off, then certainly replace them.

Also, I'd consider the power supply more if you have upgradeitis. I've never had an amp of any quality that wasn't improved by making the power supply better. Increasing the total capacitance, adding film bypass caps, replacing diodes with new ones (these have improved drastically in the last 20 years). While the Krell's usually already have a pretty decent and substantial power supply, I'm sure it could be improved. Depending on the rails and current demands, replacing the standard power supply with a CRC type can drastically lower the power supply noise, and improve low level distortion. If money is no object, you could go with a CLC pi filter instead, which offers greater capacity and lower impedance, as well as greater stability under load.

As much as that last one sounds nuts, it's exactly what I did for an aragon amplifier I had, in which I removed the internal power supply completely, and replaced it with 66uf's of onboard capacitance. I then took an aluminum DIY chassis I picked up and installed larger toroidals I ordered custom for the unit, with around 30% more capacity, 88uf's of capacitance, and 16mh's of inductance, with very low internal noise. I also upgraded it to a better quality Ixis dual rectifier bridge, with film bypass. I think the Krell is a better amplifier, and I'd guess that it has a better power supply to begin with, but this massive increase in supply I came up with gave my amplifier a much much lower noise floor, and much improved distortion. While I didn't actually test the amplifier's output, I'd have to imagine that it is now capable of greater rms and dynamic output. I wouldn't be surprised if the Krell could be turned into a much better amplifier. This is similar to Cello's amplifiers, which in many ways were similar in execution to earlier Levinson designs with much better CLC filtered power supplies.
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Old 7th March 2010, 01:39 AM   #10
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Hi Pjpoes,

I really apreciated your extense repply.
I try to maintance the original amp spec for a long time again.
I am not sure if is necesary to change the caps.
The Sprague tantalum are rated to 125ºc so I think that are ok.
I am doubt that the electrolitycs are good after tens years of use.
So I need to messure the amp to see what happening.
Originally the amp dont work, because the input board have a power resistor and relay burned.
I buy a new input board, in a few days try to run the amp for test.

Best Regards
Rubén
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