Help to id the capacitors in my preamp

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I like to recap my 20 years old preamp. However there are some capacitors I never see them before. Can someone tell me what they are so that I can get the proper replacement capacitors?
 

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Just adding a little detail to the post by Elvee.
They look like Siemens Aluminium Electrolytic capacitors, 1000 uF, 6 V. The parts that I have are marked with an S instead of EK.
I believe that the Siemens range became EPCOS which is now TDK EPCOS. I don't think that they list that type any more.
I have been told that they did have a nasty habit of firing the orange plastic case upwards if they were abused. Convential types fail a little less dangerously.
 
The preamp is about 25 years old and the audio sound coming out is very
good and sweet. Should I still bother to replace them or not? If I should,
what brand of replacement caps should I get to keep up with the high quality?

Hi,

Replace all electrolytics with decent modern versions, which
are a lot better, and leave everything else as is capacitor wise.

Film/foil capacitors have got smaller over the years, but not better.

rgds, sreten.
 
Your 68 nf etc are film which should not deteriorate based on time alone. The 1000 uf @ 6 and the 100 uf @ 40 have plus's on them and are patently electrolytic. Without the datasheets one doesn't know what these were sealed with, as late quality caps could have been sealed with silicon rubber (good) or epoxy (better). However, 99.99% of electrolytic caps in the equipment I have ever owned have service lives of less than 20 years, so I do not own a $150 ESR indicating electrolytic capacitor meter. I just replace the **** things based on the calander and overall lack of performance of a piece of old electronic gear, leading in most cases to better sound or performance with each cap I install. I sound check after every 2 caps to make sure I made it better and not worse.
Brand is not the best indicator of quality, as Panasonic, Nichicon, Rubicon, United Chemicon, Epcos, Illinois, Vishay Sprague and Cornell Dublier all sell short life caps lines sealed with **** to the the majority of customers that want those for replacement. I find reading the datasheets that United Chemicon and CD have worse ripple specs for their end of life specification, so I prefer to buy something else. I like sprague initial quality but nobody seems to stock long life versions of e-caps from them. So I mostly buy long life Panasonic, Rubicon, or Nichicon caps. I buy nothing under 3000 hours rated service life unless I make a mistake. Some vendors have the service life in the selector table, others make you download the datasheet to use this quality indicator.
I find lead spacing to be not very important where there is vertical room above the cap. However, in higher values you have to watch diameter and height to not exceed the amount of room you have on the PCB. Where my equipment has 3 volt or 6 volt caps I tend to install 12V or 25 V caps to limit the number of lines I have to purchase. Also some people say the higher voltage caps tend to last longer.
 
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The 1000 uf @ 6 and the 100 uf @ 40

The GPF print on the electrolytic caps is a DIN code, the EK series are switch tolerant types (what German lytic cap manufacturers commonly refer to as "schaltfest")
Capacitance of these caps doesn't deteriorate at switch-offs, comes in handy at phono board locations.
Replacements are smps suitable lytics, or if it's supposed to remain something German, a Frolyt : FROLYT Radial Lead Type

Next quiz : name the brand and model number of the amp.
(hints : ILP transformer, the steel plate shielding, and in particular the red-painted bolts/nuts/washers)
 
However, 99.99% of electrolytic caps in the equipment I have ever owned have service lives of less than 20 years, so I do not own a $150 ESR indicating electrolytic capacitor meter. I just replace the **** things based on the calander
I am not sure this is the best advice, especially when this is taken into account:
The preamp is about 25 years old and the audio sound coming out is very good and sweet.
Hi,

Replace all electrolytics with decent modern versions, which
are a lot better, and leave everything else as is capacitor wise.
Are you that sure?
Eugene might end regretting the butchering his beloved preamp.

I just made actual ESR measurements on some samples, including a Siemens 220µF/16V GSF in an epoxy-sealed thermosetting orange case, just like the ones pictured. That capacitor is ~32 years old.
Modern types of same value are included for comparison (@1KHz):

Code:
Siemens GSF:   76mΩ
Multicomp LL:  152mΩ
Sanyo SE8D CG: 154mΩ
Nic NRSZ:      101mΩ
Sanyo OSCON:   66mΩ

(All capacitors are unused and are relatively recent, except for the Siemens, of course)

It is interesting to note that the veteran beats them all, except the OSCON of course, but even then by not that much.

Of course, the size of the Siemens is much bigger than any of the modern ones, but in an existing situation, that doesn't matter.

One could object that it has not been used, but the actual degradation when subjected to gentle conditions of temperature and ripple is certainly negligible, and in a preamp that is normally the case.

This thread could also be of interest:
http://www.diyaudio.com/forums/parts/199046-oldies-but-goodies.html
 
Elvee I suppose the tires on your ride are also 25 years old? Low mileage ones, of course. I suppose you check the air pressure before you take your 25 year old tires out on the motorway/freeway/autobahn/tollway at 100 km/hr?
If you had a datasheet on the GSF showing it was a >3000 hour cap, that would be interesting. That would show that the sealant was better than cheap rubber. Rare, but possible. Plenty of people pay $$ for an organ that sounds great, only to have it to turn into a kazoo in 2 weeks of serious use because the historical original water evaporates out right past the cracked rubber seals.
The one thing I agree with, I have plenty of bad sounding or performing old electronics to work on instead of something that sounds good. Of what is listed here, one H182, One H112, the 10-82 tone cabinet and the Wurli 4500 are waiting recap for cause- the rest have been done.
 
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Elvee I suppose the tires on your ride are also 25 years old? Low mileage ones, of course. I suppose you check the air pressure before you take your 25 year old tires out on the motorway/freeway/autobahn/tollway at 100 km/hr?
If I had a way of being objectively satisfied the 25 yo tires are in perfect condition, I may do it, but tires and capacitors are not in the same league, both for aging mechanisms, and for the fact that tires are a life-critical component.
If you had a datasheet on the GSF showing it was a >3000 hour cap, that would be interesting.
That would be interesting indeed, but unfortunately, I don't have the datasheet.
The effective life of E-caps is something much more complex than a single figure.
You probably have some awareness of that, unless you routinely change every 5000 hour capacitor in your gear every year.

The specified life is generally estimated at or near the maximum current and temperature.
Under more normal operating conditions, the life increases according to certain laws, generally exponentially.
This means that a cap operated at around 30°C and subjected to a moderate ripple would in theory last a very long time, something like 100 years or more.
Except it doesn't.
For modern E-caps anyway.
On top of the calculated life, most have an absolute limit, a quasi shelf life.
But it doesn't need to be like that: in the early seventies, Siemens had achieved a level technological expertise close to perfection in this field.
Thanks to the purity of the materials, the construction techniques, the formulation of the electrolyte, they were able to produce capacitors of a quality that is unrivaled today, 30 to 40 years later.
That quality shows in the electrical characteristics like ESR, ESL, leakage current, but also in the stability. The inside of the capacitor is in perfect equilibrium and doesn't age by itself. The sealing too is of outstanding quality.
All this means these capacitors will outlast all capacitors made today or even in 20 years.
Using today's knowledge, technology and expertise to produce capacitors in the same spirit would result in even better components, but manufacturers simply don't do that: they make cheap and compact crap instead.

You probably think I am painting a rosy picture of the past. But at the same time, many other manufacturers had a much poorer quality, and I must have replaced thousands of caps made at around that time, particularly in HP test equipment: they seemed to have a flair for choosing the worst available alternatives.
It is also true that there is a sort "culture" in this field: US makers were inferior to european ones in this respect (and for film caps too). But they were more advanced in ceramic technology.
But even when they chose european sources, HP managed to find the crappiest available.
 
In my experience reputable manufacturers' Aluminium Electrolytic capacitors are good for many years service. They have a bad reputation because it's all too easy to misuse them.
The first rule of power supplies is that they must be cheap and small is good too. So there is a great temptation to economise on the capacitor size and also heatsinks for the semiconductors so they are in a bad environment.

I can believe that the orange electroltyics are OK if they are just decoupling so not subject to high ripple currents and also not being cooked in the power supply.
The EPCOS web sie has some information at http://www.epcos.com/web/generator/...__en.pdf;/PDF_GeneralTechnicalInformation.pdf
The Siemens ones that I have are well sealed. I can believe that it is epoxy. I assume that is why they had a reputation for failing explosively when abused.

Unfortunately most people are only prepared to pay for cheap and compact crap.
I think that HP test equipment is OK but is is designed down to a price so it's unfair to expect many decades of service. How many people keep a car for 10 years.
 
Phenolic resin actually, in those years.
Downside of the Roederstein EK types, as used in '70s gear as e.g. Quad 33, was the bakelite container, after a few decades in a hot and dry location it turns brittle and cracks.

Shelf life of the EK (+ EKU) is extraordinary.
The $13K Brinkmann Edison phono stage, introduced a year or two ago, still had a EK in each channel : http://www.brinkmann-audio.de/inhalt/en/test/edison_hr042011.pdf

E stands for Electrolytic, K for Kondensator.
EK series are regulars, EKU is the bipolar type.
 
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Phenolic resin actually, in those years.
Downside of the Roederstein EK types, as used in '70s gear as e.g. Quad 33, was the bakelite container, after a few decades in a hot and dry location it turns brittle and cracks.

Shelf life of the EK (+ EKU) is extraordinary.
The $13K Brinkmann Edison phono stage, introduced a year or two ago, still had a EK in each channel : http://www.brinkmann-audio.de/inhalt/en/test/edison_hr042011.pdf

E stands for Electrolytic, K for Kondensator.
EK series are regulars, EKU is the bipolar type.
Roederstein's are very similar to the Siemens, externally at least: thermosetting case, but brown/brick color instead of orange, epoxy sealing (it is epoxy, not phenolic). The quality is excellent, comparable to the best present capacitors, but not on the par with the Siemens: they are not as durable, and in a sample I have, the ESR is 128 milliohm, practically double of the Siemens. This one has actually been used, but not in harsh conditions, merely decoupling of a battery operated equipment.
 
it is epoxy, not phenolic

I was referring to early EK production.
In the late '80s, the series was expanded with the EKR and EKS types (S for small, and R for low ESR model)in an aluminum case, EK and EKU types changed from bakelite & phenolic to more modern plastic and epoxy resin.
(i have both the Roederstein and Siemens plastics, bought new over the years)
 

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I was referring to early EK production.
In the late '80s, the series was expanded with the EKR and EKS types (S for small, and R for low ESR model)in an aluminum case, EK and EKU types changed from bakelite & phenolic to more modern plastic and epoxy resin.
(i have both the Roederstein and Siemens plastics, bought new over the years)
They are specified very conservatively: on the 220µ/16V EK I have, the ESR @100Hz is 301mΩ. The advertised value is 1.16Ω. And this one is not a NOS, it has been in use.
In the same conditions, the Siemens GSF is at 221mΩ.
 
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