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Old 18th Feb 2014, 2:48 pm   #1
Okto1984
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Default Capacitor described as "-10+50%n", but what does the 'n' mean?

This has me puzzled. I've found a "100uf 200v -10+50%n" axial in my TV's schematic and it's the only capacitor described with an n at the end. The service manual says nothing more about it and googling didn't turn up anything either. While I first suspected non-polar as it's a bulky thing, the PCB and schematic show polarity markings like all the other electrolytic caps.

Just want to figure out that puzzling little 'n' before I do anything with it. It might be some essential feature to simply work, or some important safety thing!

Any help much appreciated.
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Old 18th Feb 2014, 3:35 pm   #2
vidjoman
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Default Re: capacitor described as "-10+50%n" but what does the 'n' mean?

Details of the set might help. Maybe it's sleeved or non-sleeved. Look at the original and see if you get a clue.
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Old 18th Feb 2014, 5:06 pm   #3
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Default Re: capacitor described as "-10+50%n" but what does the 'n' mean?

I suspect that the markings on the capacitor mean that the actual value is from -10% of nominal up +50% of nominal, rather than the more usuall symetrical tolerance range.

That is from 90% up to 150% of the nominal value.

Such tolerances are more often found on capacitors for power factor correction, or for power supply smoothing.
A value significantly LESS than nominal wont give the desired result, but a greater than nominal value is fine, within reason.
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Old 18th Feb 2014, 7:40 pm   #4
Okto1984
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Thank you both for the suggestions.

It's a beovision 7802 and the capacitor in question is on the secondary side of the power supply, it's smoothing one of the outputs from the flyback transformer which is going to the scan board and appears to be powering the deflection coils.

It may mean nominal, but virtually all the other capacitors are described as -10+50% or even -10+75%, and none have this odd little n.

The capacitor itself looks like an ordinary enough gold Roedenstein axial. I wouldn't suspect anything special from just looking at it.

May well turn out to be quite ordinary, but I'll wait a little while and see what turns up here, and if another googling when I'm thinking about different ways to describe it finds something before doing anything with it.
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Old 18th Feb 2014, 7:52 pm   #5
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

I don't know what the 'n' refers to specifically, but -10+50% is a quite normal tolerance for general-purpose smoothing electrolytics.
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Old 18th Feb 2014, 8:11 pm   #6
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

is it definitely an 'n' or is it the greek symbol Eta? Maybe a footnote elsewhere?
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Old 21st Feb 2014, 3:39 pm   #7
Studio263
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

The capacitors in that position give very little trouble, no need to replace it unless it is obviously faulty (short circuit or bursting open). If you want to change a capacitor in this set the one to go for is the one that couples the frame coils to the frame output stage (but only if this the 4 -legged sort), these do give a fair amount of trouble.

The 77XX chassis isn't one for capacitor troubles on the whole. Soldering problems yes, capacitors not so regularly. Have a look through the Notebook on www.beocentral.com for more 77XX servicing tips.
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Old 21st Feb 2014, 5:54 pm   #8
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Perhaps the "n" is a mistype that has been religiously transposed to the schematic by whoever copied it, maybe with very little or no technical knowledge?
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Old 22nd Feb 2014, 11:02 pm   #9
Okto1984
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Thank you for the further ideas.

I don't believe it's an eta, looks like the same character n as elsewhere. No footnotes either.

A typo is possible, I'm starting to lean towards this, although n is not close to the % key on the English, Danish or German keyboard.

As for capacitor replacements, recapping vintage items that otherwise work gets very varied opinions. I didn't know what to think, so as an experiment I decided to replace them on account of their age to see what if any difference it would make. I intend to update here with the final results when finished, but can already say this specific set was under performing and I didn't realise it before. The picture and sound have benefited. It did however work perfectly acceptably before I started, so it was not essential. Originality may matter more to some people, and others might be quite accepting of ageing as long as it still works (I also have a completely original beovision 9000 I'm happy with and use most days), but I just want to turn back the clock with this one and attempt to see what it looked and sounded like when new.

I'm thinking the 4-leg capacitors are the radial ones with a round plate with three legs around the outside and a single central one? Or have I misunderstood?
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Old 26th Feb 2014, 9:05 pm   #10
Okto1984
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Well, I put in a new capacitor a few days ago. A regular electrolytic polarised Rubycon with the correct uF, V and better ESR/ripple than the original, and it works great. I guess the 'n' didn't mean anything much in the end.

This capacitor was also a pain by being axial too. Nobody it seems makes 200V axial capacitors with low ESR and high ripple current. The Rubycon BXF radial I used however matches the electronic requirements while being short, light and wide, so it turned out to be a very good replacement in this situation. Despite the substitution, the end result is tidy and solidly attached.

Anyway, thank you everyone for the suggestions. I'm glad I checked, as I want to be sure all replacements parts are safe and work properly.
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Old 27th Feb 2014, 2:24 pm   #11
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Higher Working Voltage capacitors tend to be sold as high ripple current or high endurance capacitors rather then as low ESR.
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Old 28th Feb 2014, 1:25 pm   #12
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Quote:
Originally Posted by Okto1984 View Post
I didn't know what to think, so as an experiment I decided to replace them on account of their age to see what if any difference it would make.
My guess would be "none" unless ther originals are actually faulty. This can be determined by measurement, either of the component characteristics or of the operating conditions of the circuit.

I've been working on these sets for years, both for my own use and for other people. The only faulty capacitors in the power section tht I've come across have been the small ones around the SMPS control IC, and then only rarely. Some versions of the video / IF panel get hot around the sync / line TB IC and make the capacitors in that area look careworn, but they always measure OK so I let them be.

By all means change them all if you enjoy doing it but the whole joy of the 77XX chassis is that to really don't have to, the originals were that good. That pre-set that controls the 5V s/b supply though, that's a whole other issue...
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Old 28th Feb 2014, 9:37 pm   #13
Okto1984
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Hi Maarten, that's interesting about higher voltage capacitors. I'm finding the descriptions quite varied from manufacturer to manufacturer.

Studio263, this is also interesting - and reassuring about my other similar beovision, which despite being a little older than this set doesn't have the very tired sound this one did when I first received it.

I'm not sure what the "pre-set that controls the 5V s/b supply" is however? I'm wondering if s/b is standby? My set does have the strange habit of waking itself up when in standby.
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Old 1st Mar 2014, 2:57 am   #14
Maarten
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Default Re: Capacitor described as "-10+50%n", but what does the 'n' mean?

Long life is another description that is sometimes used.

s/b does indeed mean standby.
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