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Old 21st March 2012, 12:18 PM   #1
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Default Capacitor advice please

Hi. Looking for capacitors to replace the cheap nasty electrolytics in my dacmagic 1. My first mod project so please excuse my ignorance.

First queston....I have found this guide on upgrading a dacmagic 2 , and it recommends changing some of the values, would i be able to use this guide as a reference for the values required, and what effect/benefit does changing the values offer? or am i better replacing caps like for like. (http://lickham.co.uk/pdfs/dacmagic.pdf)

Second query......Could someone recommend which capacitors would be best for replacing the existing ones....I was advised to use, rubicon zl for the big 3300uf and 2200uf caps, but they dont go up to 3300uf 25v, would the ZLH be a better option for these? And was told rubicon za for >6v and sanyo ocson for < 6v,

I had considered nichicon or elnas, but i am unsure which caps will be best used for which section on the pcb. Wanted to use some reasonably high quality caps, that dont cost a fortune.

Thanks
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Old 21st March 2012, 12:30 PM   #2
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I'm much like you, almost a newbie. I can share some links that provide much information (legend?) about caps. I have done some of the mods to the MUSE Dac mentioned. I have dabbled in high-end caps. I'll admit I can't hear a difference, good or bad. But I will follow this thread with interest! Thank you.

Doing your own DAC mods: a Primer

Capacitor Musings Article By Jon L DIY Audio Kits Reviews

ecp.cc
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Old 21st March 2012, 04:40 PM   #3
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I've replaced all electrolytic capacitors in 3 power amplifiers, a preamp, a disco mixer, 2 radios, and 2 hammond organs in the last two years. I'm listening to a 1970 dynakit amp, and a 1992 disco mixer (turntable magnetic cartridge interface) right now. My computer stopped talking to peripherals 2 weeks ago and I replaced 2 caps on it to get back online. More caps are on the way to do them all in the PC. I buy e-caps based on the hours design life. Nothing under 3000 hours. There have been no hum problems after I put these in- I think the cheap **** is being screened out. Rubicon, Nichicon, Panasonic, all make short life and long life caps. Buy the long life ones. United Chemicon I have uised, but their life spec has a worse ripple current at the end of life than the first three, so they are "massaging the numbers" to look good. Where the equipment has can caps (1970 or earlier) I pull the can out, plug the hole with screen wire, and install solder terminal strips from tubesandmore.com or triodeelectronics.com. In europe some guitar parts shops have turret board which can be sawed up, but I haven't seen any TRW Cinch type solder terminal strips. When you drill the hole to install the screw for mounting, use a magnet to pick up the trash as you drill. I use a hand crank drill for #6 machine screw holes.
Farnell has the hours life on the selector chart, other vendors you have to download the datasheet and read it.
Tin-Lead solder I use a WP25 iron mostly, but on the ROHS compliant PC board I had to use a 130 W pistol iron and then after I had the components out, drill the holes out with a pin vise. Europe wants more and more electronics in their landfills, I can tell. They have legally required silver solder holding in caps with a design life of 1 to 5 years.
I don't have an opinion about changing parts values. One can download an Electronic Design Assistant (see wikipedia EDA) on an up to date computer and run simulations, or buy the parts and try them out. Usually shipping charge is more than the caps I buy.
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Last edited by indianajo; 21st March 2012 at 04:59 PM.
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Old 21st March 2012, 05:44 PM   #4
RJM1 is offline RJM1  United States
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< 25V capacitors I always replace with 25 or 35V capacitors, especially 6 and 16V 1000uF capacitors in SMPS. They allways fail but when replaced, never come back.
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Old 21st March 2012, 06:58 PM   #5
jitter is offline jitter  Netherlands
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@indianajo

The reason why Europe has gone the RoHS route is because a lot of equipment will end up as landfill rather than being recycled, despite having several (free) options for recycling at our disposal. Reason: it takes less time to chuck something in the bin than bring it to a collection point, so some of us will always be tempted not to recycle.
The amount of electronics in households has gone up from a few items to many many more in the last few decennia. As a result, the amount of discarded electronics in landfill has also gone up dramatically.
Because lead is poisonous and will eventually leach into the groundwater, it was inevitable that this had to come to a halt.

Yes, leadfree solders (contain only a very small amount of silver, BTW) are harder to work with, but now that some time has gone by, leadfree joints are proving stronger and longer lived than joints with lead.

The RoHS directive isn't limited to lead. It also restricts the use of:
Mercury (Hg);
Cadmium (Cd);
Hexavalent chromium (Cr6+);
Polybrominated biphenyls (PBB);
Polybrominated diphenyl ether (PBDE)
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Old 22nd March 2012, 12:32 PM   #6
marce is offline marce  United Kingdom
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The lead in electronics is a minor percentage of the world usage of lead, in the bottom 1%. The lead in tin lead solder does not leach out that readily, so would not actually pollute the water system, like the fear mongers would have us believe. Solder joint reliability, work and research is still being done on that one, hence life support and high rel is not using it yet.
Of course we now burn more energy to produce the elctronics, due to the higher reflow temperatures, so its not all bad.
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Old 22nd March 2012, 01:23 PM   #7
RJM1 is offline RJM1  United States
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Tin whiskers and other facts about lead free solder.
http://nepp.nasa.gov/WHISKER/referen...ic-Pb-free.pdf

Summary quote.
"No mitigation technique other than the addition of at least 3% Pb by weight to Sn has proven itself to be totally adequate in the field
–Multiple research efforts to develop effective mitigation for tin whiskers"

Another excerpt.
Lead leaching into ground water.
Attached Images
File Type: jpg 1-Lead -leaching.JPG (114.5 KB, 277 views)

Last edited by RJM1; 22nd March 2012 at 01:40 PM.
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Old 22nd March 2012, 04:44 PM   #8
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If Europe was serious about keeping electronics out of landfills, they would have required 10000 hour electrolytic caps. (epoxy sealant instead of rubber). I believe this legislation was written by the ignorant to fill the needs of large corporations that enjoy the prospect of selling the same customer over and over again. The whole lead usage thing went insane when everybody was buying a new PC display every 11 months, each of which had lead X-ray shielding. The caps in displays were lasting about a year, as were the caps in the switcher power supplies in the PC's. I've got a stack of dead PCAT supplies and CRT's. Maybe next winter I'll be skilled enough to fix my first switcher supply. Up to now I've been cutting them up for RF chokes, NTC resistors, and lightning arrestors (MOS)
As far as keeping equipment out of landfills, all it takes is a little gold. You can't buy a dead PC around here except at Goodwill/Salvation Army, and people in Florida tell me that is illegal there. I didn't even get the CPU back on the PC I turned in for a bad PCI bus slot struck by lightning. That ******* repairman threw away the whole mainboard and my Windows 98 source disk, too. PC salvage all goes in a big drum at the PC repair place, to be shipped off somewhere for money. I could really use several dozen of salvage 0.3" spacing headers to make an organ stop sequencer, but I've found 2 salvage $4 PC's in a year.
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Last edited by indianajo; 22nd March 2012 at 04:55 PM.
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Old 22nd March 2012, 05:11 PM   #9
marce is offline marce  United Kingdom
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And I was brought up in a house with lead water pipes as a kid and it hasn't done me any harm, has it Mavis!
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Old 22nd March 2012, 05:36 PM   #10
jitter is offline jitter  Netherlands
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@RJM1

Interesting read, but there's a lot I have my doubts about.

E.g. the whiskering problem is something I have not yet witnessed, and I have been working nearly 6 years with leadfree solder and leadfree products. I work in industrial electronics, BTW. Also, in those six years I have not seen an increase in inexplicable faults or increase in products returned for repair.

True, in the beginning of the leadfree era, everyone in the company I work for had to adjust to the new process and there were some solder process related issues that had to be solved. They have, and apart from a higher tendency to form solder bridges between closely spaced pins during wave soldering, there aren't really any problems with leadfree soldering that stand out.

When it comes to desoldering through hole devices from pcbs with fully plated holes, I prefer SnPb solder. Other than that, I don't really care. And yes, we still make a number of products with SnPb solder, including some that I can't imagine being exempt from RoHS regulations.

The fact that medical and transportation are going to lose RoHS exempt status pretty soon means that leadfree has proven itself enough to make that happen. In fact, we have been producing leadfree for a customer in medical appliances for several years now.

Was there as much apprehension about unleaded fuels as there is about leadfree solder?

Last edited by jitter; 22nd March 2012 at 05:41 PM.
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