Sansui big capacitor replacement - disappointment

[restorer-john]

Quadbob, Agreed. Shoot that glue salesman. I have cursed his name many times while scratching cement-like brown goo off pcbs, redrilling the holes (otherwise the cancer continues) and extracting useless components. What was the deal with hiding links under all that brown goo? Or my personal favourite, a 1N4148 or a tiny zener under the brown goo sitting next to the rotten filter caps. :thumbsdn:

 

[Kjell-B]

EXAMPLE=

My 7070..........that was barely used then stored on a bench in a basement for YEARS with zero use.

According to "scientific evidence" presented here--------->

This 7070 should be LONG DEAD........it should have mucho dead caps.

YET--------->

It functions PERFECTLY............only a bulb needed replaced in it.

SOUNDS GREAT!

hmmmmmmmmmmmmmmm..........................:scratch2:

And this is not the ONLY vintage (70's) receiver I have that is like that.

WHY????????

They should all be long dead..........the caps are WAY PAST the life they should have according to science ( and science is proved all the time to be nothing but evolving theory). :scratch2:

When the caps have lasted that long they may continue for 500 years.
I believe this is the best test for electrolytic capacitors - the "long life-test". When 35 years passed without trouble, they will last very long.

And current manufacturers state only 15 years .... A good cap is then replaced by a lesser one.

 

[pahtcenter77]

I have a Sansui amp that is in need of "freshening up", so I have quite an interest in this thread. I have read it twice, and some parts three times. Since I do not have much electronic expertise, I am relying on info such as this to determine how much work to have done on it, as well as recommendations from the tech I select to do the work.

Both sides seem to agree on one point - that "caps" are similar to batteries. They consist of plate(s) and electrolyte. If I am correct in that assumption, then they might be compared to car batteries. Although some seem to last forever, car batteries fail. Proper usage and maintenance (as in electric forklift batteries) make them last alot longer, but they eventually give out. With that information, I propose the following scenario:

I am going to send my teenage daughter from away to college. I will give her my 1997 Chevy pickup as a vehicle, and she and ????? will be driving it cross-country during the summer. I send it to my mechanic for a tune-up, to include belts, hoses, spark plugs, wires, oil and filter, tranny service, etc.

The battery has a 5 year warranty, and is about 3 years old. It seems to start the vehicle just fine. Should I have it changed? I'm sure a new one might not act EXACTLY the same as far as starting or charging, but I doubt I'll notice the difference. Should I leave the old one in, not really being sure of the consequences if it fails later?

Feel free to show me the error of my thinking.

77

PS I'm gonna change the battery.

 

[hpsenicka]

When the caps have lasted that long they may continue for 500 years.
I believe this is the best test for electrolytic capacitors - the "long life-test". When 35 years passed without trouble, they will last very long.

And current manufacturers state only 15 years .... A good cap is then replaced by a lesser one.

I believe your logic here is based on a series of flawed assumptions.

Firstly, you assume that a capacitor that has not suffered a catastrophic failure is still working within spec, and will continue to do so.

Secondly, you suggest that the best test for an electrolytic capacitor is whether or not a complete failure has occurred, effectively dismissing the value of engineering design, and electronic measurement.

Thirdly, you assume that having survived well beyond the designed service interval, that you can extrapolate an indefinite (or effectively infinite?) service life in practical terms. That makes about as much sense as expecting them to fail the day after their "best-before-date" has passed.

Fourthly, because manufacturers continue to state a conservative service life of approximately 15 years ( as they have in the past), you assert that these products are inferior. I don't believe manufacturers and designers are behaving any differently in this practise than they have for decades, and this is not a reliable basis for predicting component life.

It seems to me that all of these points are flawed, and your entire premise is not logical.

You have raised some thought provoking questions elsewhere in this thread, but in my mind you have been unable to successfully prove or defend any of your assertions. I welcome a good discussion or debate as much (or perhaps even more than ) most folks, but controversial or extreme positions must be well supported in order to be taken seriously.

 

[Crazy]

I believe your logic here is based on a series of flawed assumptions.

..........................................................................................
It seems to me that all of these points are flawed, and your entire premise is not logical.

You have raised some thought provoking questions elsewhere in this thread, but in my mind you have been unable to successfully prove or defend any of your assertions. I welcome a good discussion or debate as much (or perhaps even more than ) most folks, but controversial or extreme positions must be well supported in order to be taken seriously.

WELL.......the fact that many hi-fi's still function perfectly after years of use & non-use proves that the "theory" all caps "should" crap out long before this time to be a "flawed assumption".

What I can't get is WHY "some" ..."seem" to go out of their way to avoid a simple fact such as this???????????????

Like I said before............science, which is nothing more than an evolving theory, must be tempered with common sense. Nothing is cast in stone.

Another thing to be considered is if one is a rabid collector, a museum curator or just some average Joe enjoying the sounds coming out of his "used" $100 receiver.

Me...........I'm that average Joe.

Putting a stupid outlay of cash into some used hi-fi that can be replaced way cheaper and with more ease, is kinda dumb to me.

But...........that's me............just an average Joe "attempting" to use common sense--------->

Yep.........I'm just grooving on listening to my "cost effective" good sounding stereo that I couldn't afford to buy when young in 1973.

To get stupid about it, only removes the fun.

But that's me...........

To each their own.

I guess another 20 years or 30 years we will all know rather than predict and assume based on "theory".


PS------------> a stereo is not in the same class as reliable transport for a young child. Sorry...........NO COMPARISION............let's keep it in perspective shall we. :thmbsp:

 

[hpsenicka]

Crazy... I don't see anyone telling you how to spend your money. That is a personal decision each individual makes according to their needs/wants and their budget.

So far this discussion has been mostly focused on the technical reasons behind replacement of aging electrolytic capacitors, and the sonic implications of doing so.

 

[EchoWars]

EXAMPLE=

My 7070..........that was barely used then stored on a bench in a basement for YEARS with zero use.

According to "scientific evidence" presented here--------->

This 7070 should be LONG DEAD........it should have mucho dead caps.

YET--------->

It functions PERFECTLY............only a bulb needed replaced in it.

SOUNDS GREAT!

hmmmmmmmmmmmmmmm..........................:scratch 2:

And this is not the ONLY vintage (70's) receiver I have that is like that.

WHY????????

They should all be long dead..........the caps are WAY PAST the life they should have according to science ( and science is proved all the time to be nothing but evolving theory).

In debate, this is called a 'straw man'. No one said your receiver should be 'LONG DEAD'.

Look up the definition of non-sequitur.

 

[Negotiableterms]

...Both sides seem to agree on one point - that "caps" are similar to batteries...

Here's the flaws in your logic:

First, if the car battery fails, baring some bizarre result where you're caught in a snowstorm and die, nothing much goes badly. The battery fails, the car doesn't start, and it's over.

When some random cap in some random place fails, it can do so in a benign manner, like a car battery, or it can fail catastrophically, annihilating the whole unit by taking out some little bit of vintage unobtanium. If your car battery could wipe out the car when it failed, you'd replace it looooong before it got to the end of its warranty, no? In fact, you're replacing the battery now because of the tiny likelihood that its failure could wind up harming your daughter, right? I'd make the same call.

Second, there's only one battery in the car. There's dozens of caps in a receiver, maybe hundreds. Would you want to take the car into the service place at random intervals whenever one of its dozens of batteries fails? Of course not; the cost of downtime and towing and service charges makes it obvious that you'd replace the whole bunch at once, providing a refreshed service interval.

Third, there's the value maintenance factor. If the car battery fails, the value of the car is not affected. If a cap failure takes out the transformer, and you have to replace the entire power supply with a completely redesigned one, the unit could be worth much less than when it was closer to stock.

In another thread here, I got the wonderful news that the transformer in my Marantz 2600 was not blown. I asked Glenn to replace anything that can be replaced, and to redesign the power supply for more stability and less likelihood of transformer blowout (2600s are famous for that). My goal is that 30+ years from now, when my son inherits it, it won't be just a pretty faceplate, but will be fully functional. If that means I have to replace it all again in 20 years, so be it... I just hope Glenn's around to do the job.

 

[eradoncic]

Yep, Crazy, I've been scratching my head trying to decide if I'm firmly on either side, or trying to look at the best parts of both sides, or wether I should say the heck with it all, & let a repair shop worry about it. But the thing is, it's darn interesting, & I WANT to learn, so I'm in it to stay. Something that occurs to me is, maybe the Sansui "sound" has NOTHING to do with the caps, & everything to do with their transformers. :scratch2: :

This can be true...interestingly, in my Alpha907DR unit, there's only 9500Uf capacitance (5600+3900uF/85V) per rail, for assumed 2x160w/8 ohms; Needles to say say, for assumed power, mostly orhter amps have at least 20000Uf per rail, so I beleave too something is to do with the transformer as most critical part of audio amp power supply.

Still, the amp was made in 1992, was in mint condition (used occassionally) and during first week of working, was a bit too hard in bass and not as clear as the previous model I had (707DR, both are in AK's data base). I thought it was because of underbiased OT, but it was proved isn't.

@all: what is your comment, should I change those PS although they looks as from the factory? I checked several smaller caps (Elna Silmics), and all values seems to be within 10% of nominal values...

 

[restorer-john]

Yes eradoncic, the transformer is the most critical part of the power supply for a power amp. It appears impossible for some to actually comprehend their treasured capacitors are secondary (pun intended). The fact that Sansui (notably) traditionally used a massive, highly regulated transformer over a cheap, poorly regulated one with a bunch of caps strapped on the end, is testament to their engineers' understanding of sustained musical power demands and the inability of a large value bank of caps to adequately prevent rail sag and consequent dynamic power supply modulation induced distortions and transient compression. Until it is accepted here that the transformer is directly driving the load via switched transistors with some smoothing help from a few caps, half this discussion falls on deaf ears (pun intended again). Plenty of amps used the high voltage, sloppy (unregulated) transformers and big caps to give lightweight, cost effective amps with impressive transient capabilities but poor long term results. The other way is the highly regulated, tight supply with a dynamic power virtually the same as the steady state. There are so many valid ways of producing the power, but for my dollar, I want continuous, tightly regulated supplies with plenty of copper and steel in the transformers and as much capacity in the caps as I can have. That is the engine, all you need then, is a good car.

 

[Kjell-B]

Yes eradoncic, the transformer is the most critical part of the power supply for a power amp. It appears impossible for some to actually comprehend their treasured capacitors are secondary (pun intended). The fact that Sansui (notably) traditionally used a massive, highly regulated transformer over a cheap, poorly regulated one with a bunch of caps strapped on the end, is testament to their engineers' understanding of sustained musical power demands and the inability of a large value bank of caps to adequately prevent rail sag and consequent dynamic power supply modulation induced distortions and transient compression. Until it is accepted here that the transformer is directly driving the load via switched transistors with some smoothing help from a few caps, half this discussion falls on deaf ears (pun intended again). Plenty of amps used the high voltage, sloppy (unregulated) transformers and big caps to give lightweight, cost effective amps with impressive transient capabilities but poor long term results. The other way is the highly regulated, tight supply with a dynamic power virtually the same as the steady state. There are so many valid ways of producing the power, but for my dollar, I want continuous, tightly regulated supplies with plenty of copper and steel in the transformers and as much capacity in the caps as I can have. That is the engine, all you need then, is a good car.

I think this is one of the best posts in this thread.

When I built my tube preamp (with low impedance output), I tested a long range of power transformers, and even if we are speaking of a preamp here, a huge heavy power transformer was more important than almost everything else. Of the many tested, some old EI core transformers (standard type from the 60's) were best. Well, I had two, so I built a dual PSU with two transformers.

None of the new production transformers I had bought from electronic shops were good; the only that could be used, were toroidal ones, but they were not as musical and with as heavy bottom (bass) as the old EI.

 

[Crazy]

In debate, this is called a 'straw man'. No one said your receiver should be 'LONG DEAD'.

Look up the definition of non-sequitur.

The caps in all these "stock" 70's receivers are "long past" their life span ( as stated by you and others). Yet they still live. Nothing absurd about this.......just a simple fact arrived at using simple observation.

And hence the point.

What would be absurd would be to ignore this point.

 

[Crazy]

Yes eradoncic, the transformer is the most critical part of the power supply for a power amp. It appears impossible for some to actually comprehend their treasured capacitors are secondary (pun intended). The fact that Sansui (notably) traditionally used a massive, highly regulated transformer over a cheap, poorly regulated one with a bunch of caps strapped on the end, is testament to their engineers' understanding of sustained musical power demands and the inability of a large value bank of caps to adequately prevent rail sag and consequent dynamic power supply modulation induced distortions and transient compression. Until it is accepted here that the transformer is directly driving the load via switched transistors with some smoothing help from a few caps, half this discussion falls on deaf ears (pun intended again). Plenty of amps used the high voltage, sloppy (unregulated) transformers and big caps to give lightweight, cost effective amps with impressive transient capabilities but poor long term results. The other way is the highly regulated, tight supply with a dynamic power virtually the same as the steady state. There are so many valid ways of producing the power, but for my dollar, I want continuous, tightly regulated supplies with plenty of copper and steel in the transformers and as much capacity in the caps as I can have. That is the engine, all you need then, is a good car.

I too find your post to be one of the best in this thread.

And surely one of the most enlightening for me.

Could it then follow that a really good power supply would tend to be less hard on caps and therefore cause them to retain good condition much longer (along with the other components)?

 

[hpsenicka]

The caps in all these "stock" 70's receivers are "long past" their life span ( as stated by you and others). Yet they still live. Nothing absurd about this.......just a simple fact arrived at using simple observation.

And hence the point.

What would be absurd would be to ignore this point.

Would you expect a 90 year old athlete to compete effectively in an Olympic event?

He's still alive, ambulates on his own, and appears to be healthy... :scratch2:

What are your performance objectives... to start the race? to finish? to place competitively? or to win?

Your position apparently fails to consider a standard for acceptable performance... or the effect of aging components on the performance of a device. It isn't as simple as does it work... yes or no?

 

[Crazy]

Crazy... I don't see anyone telling you how to spend your money. That is a personal decision each individual makes according to their needs/wants and their budget.

So far this discussion has been mostly focused on the technical reasons behind replacement of aging electrolytic capacitors, and the sonic implications of doing so.

Actually.........when a person is told his caps are old and likely bad..........and will likely die or worse maybe explode...........and they "NEED REPLACED" because of this.

This is INDEED TELLING THEM HOW TO SPEND THEIR MONEY..........or at least hinting at that. :lmao: :lmao: :lmao:

Pretty important statements. Stuff that can make a person paranoid.

And yes.........then we get to the question of if replacement then alters sound. Different opinions on that one also.

Bud..........I think we are pretty much still on subject.

Problem seems to be that certain "realities" are ignored in favor of dogma by some. :yes:

Again......common sense will help a human sort it out.

But first one must have an open mind.:thmbsp:

 

[Crazy]

Would you expect a 90 year old athlete to compete effectively in an Olympic event?

He's still alive, ambulates on his own, and appears to be healthy... :scratch2:

Well.............now you are just getting silly........:lmao: :lmao: :lmao: :lmao: :lmao:

But hey..........I have a 1975 Chevy with the original 292 that has well over 300,000 miles and it still out hauls newer trucks. Should I pull the motor and tranny and junk them and put in new stuff??????

I think not.

Someday.........when it needs it..........not before. Oh...and when I do it will be the same stuff I take out. Ya can't do that with a Sansui...so replacement parts is another issue.:thmbsp:

Your position apparently fails to consider a standard for acceptable performance... or the effect of aging components on the performance of a device.

Not at all........but pointing out that stuff is doing fine long after the stated life. And I'm liking it and using it. Pretty important points.

It isn't as simple as does it work... yes or no?

In a way it is that simple......no problems........it works........I use it.............fix or replace it when needed.

SOMEHOW..........I don't think I'm the only human on this planet that see's it that way.

 

[eradoncic]

Yes eradoncic, the transformer is the most critical part of the power supply for a power amp...etc.

Thank you very much for this enlighting post. But, can I ask you once again, what you think, should I replace the PS caps, as according to previous posts/statements, leaking or drying of the capacitors is almost inevitable thing? They looks very good, but....

Also, one more question - should the transformer become warm, even hot during idle? I noticed, without signal, after turning it on for 1h or more, the transformer is hotter than the heat sinks themselfs, and I never experienced this with other amps (mostly toroidal based PS).

Can this be some sign of vanishing PS capacitance?

The amp in question is this one (my original pics):

http://www.sansui.us/AU-Alpha907DR.htm


Thanx

 

[Morden2004]

We're done!

Well, I think this discussion is just getting goofy and fails to address reality. I think it's time to close it.

There is nothing whatsoever usefull in a statement that says "after 30 years my XYZ 9000 is still pumping out music so those old electrolytics must be in excellent shape".

I'm sorry, that is just pulling the blinders over your eyes (ears?) and completely ignoring the science. If you have no benchmark and only your unqualified analog ears as a test instrument, then it's clearly a statement meant to incite more useless dialog.

As Judge Marilyn Milian on Peoples Court says "stick a fork in me, I'm done".

We're done.

Paul

 

[nosirrah]

Unstuck, now this one can migrate off to eternity...
Action performed at the members request.