Capacitor Tolerance with Negative Tolerance Only - Page 1
Forum section: electronics / beginners

author: TinkerGDS
author_rank: Contributor
timestamp: November 11, 2016, 01:32:04 pm
content: I am replacing the capacitors on a Revox B261 Tuner. I have the service manual and started making a list of all of the electrolytics. I thought I understood capacitor tolerance: +-20%, -20% +80%, but most of the ones in the service manual are rated at -10% only. I don't understand what that means. Is that a shortcut for -10%, + 20%. I expected to see some information in the service manual like, all values represented are 20% unless otherwise noted, or something to that affect. So I'm not sure if there's a standard for parts and value listings, or if there really is such a capacitor tolerance as -10%.

author: danadak
author_rank: Super Contributor
timestamp: November 11, 2016, 03:26:30 pm
content: Different Cap technologies have different tolerance specs. They even have parts whose C rating isvery sensitive to the V across them.Are you just replacing electrolytics ?http://www.kemet.com/Lists/TechnicalArticles/Attachments/6/What%20is%20a%20Capacitor.pdfhttp://www1.eere.energy.gov/solar/pdfs/8_tuttle.pdfRegards, Dana.

author: TinkerGDS
author_rank: Contributor
timestamp: November 11, 2016, 04:10:39 pm
content: Those are two great documents. I've saved them in my reference library.Yes, I am just replacing the electrolytics. I am not trying to make the tuner "better", I just want to bring it back to its original state when it was new back in 1982.

author: Cliff Matthews
author_rank: Unknown
timestamp: November 11, 2016, 04:30:05 pm
content: Ditto here, I love this place! Thanks Dana.

author: Kalvin
author_rank: Super Contributor
timestamp: November 12, 2016, 02:13:29 pm
content: Quote from: TinkerGDS on November 11, 2016, 01:32:04 pmMy guess is the -10% notation means that the capacitance may be 10% less the nominal without compromising the sound quality, but it doesn't matter if the capacitance is higher than the nominal (+10% or %20, for example).

author: TinkerGDS
author_rank: Contributor
timestamp: November 13, 2016, 08:45:53 pm
content: Interesting. Thanks.

author: B1nary
author_rank: Contributor
timestamp: January 12, 2017, 02:05:44 am
content: Quote from: TinkerGDS on November 11, 2016, 01:32:04 pmI have the same tuner and wonder if you did an alignment on it or if something else prompted the cap replacement. If I may be so bold perhaps try an alignment to see where it's at. It might save you a ton of work. I've never done my alignment but I'm wondering if anyone here might have and what they used for an rf generator since the standard SencoreSG165 and the Sound Technology 1000A most techs used are older than the tuner and have questionable performance unless well maintained. If anyone has our is doing an alignment, what are you using for the rf portion?

author: TinkerGDS
author_rank: Contributor
timestamp: May 21, 2018, 01:15:29 pm
content: I have a number of Revox components. The first few I picked up were in non-working condition. I did not know much about the units so I purchased a recap kit from a Revox store on eBay. The kit contained all of the capacitors for the unit. After the full cap replacement the unit started to work, and still works great. Since then, I have decided to replace all of the EL caps on every unit I have. I've tested many of the capacitors I have replaced. Some were dead and some were marginal. I did not want to take a chance that the marginal ones would fail soon and I'd have to do another teardown and rebuild. The B261 tuner was no different. I replaced all of the capacitors. Then I decided to do the tuner alignment after checking some of the performance specs and seeing that it was not quite perfect anymore. I use an HP 8662A Signal Generator that I brought back to life for my alignment. It has a very good frequency range - way more than I need, but it can sweep, and it has a very wide attenuation range, that I really like.