Sansui big capacitor replacement - disappointment

[restorer-john]

QuadBob, you really have to be careful when taking this:

"2) The only way to prevent evaporation is to SEAL the cap...........which again referring to the construction of electrolytic capacitors you will find that they all MUST include a "VENT". Why? Very simply because depending on the AMBIENT temperature and the electrical charge passing through them......... they give off gas and expand/contract depending on temperature. If they were sealed.......they could explode or bulge when expanding. Their vent allows them to expand/contract as needed to maintain stability."

And turning it into a FACT?

"So from the above we can add a new FACT to this thread:

FACT: All electrolytic capacitors are subject to evaporation of their electrolyte whether in use or in storage"

All electrolytic caps MAY be subject to evaporation... is a more correct statement and certainly still not a fact. To date, your experience and numerous others anecodatal muses are still not FACT.

Not only that, the vent can be described as a last resort protection for the cap to prevent a catastrophic failure. A cap expanding and contracting and venting as you described is not stable. It is about to fail. Any cap with any bulging or evidence of venting should be replaced in my opinion, regardless of its measured value.

We all know caps leak, we all know they dry out, we all know batches can be bad (I did a Quad34 preamp where every identical value/identical batch cap had leaked and eaten the PCB, but all the others were fine)

The subject was about power supply caps, not coupling or any other caps. As usual, the thread gets polarized into a old vs new, recap vs not thread with all the usual suspects weighing in. I seriously think capacitors are getting the same level of snake oil all over them that cables have attracted.

There is no doubt restorers like us could do without the problem, but it is going to be an endless source of trouble for years to come.

My issue is if we accept some capacitors detreriorate, some fail completely and some work perfectly for an indeterminate period, are we replacing superior components with inferior ones? Seriously, how long do you think a modern Nichicon Fine gold will last compared to the 1970s functioning Elna you took out? I've seen 3 year old Rubycons fail in my parts drawers, still on their pick and place looms.
It's a discussion that always goes the same way, because if all the capacitors in our vintage equipment lasted as long as their rated life and adhered to the manufacturers MTBF data, the old gear would have been in the landfill 15 years ago with 100% failures. It didn't fail and now the problem is, do you replace PROVEN caps with a life greatly in excess of their ratings with new products with no such proven life?
There is no one outcome here and never will be as you guys will be replacing today's replacement capacitors in 10 years when some of the old 1970's ones are still working as they did 30 years before.
It's all fun anyway, until the brown goo the Japanese used eats up a PSU electro's lead and the whole amp goes up like a flashbulb.:thmbsp:

 

[Kjell-B]

OK, Bob, we'll keep it open as long as we are having a constuctive discussion. Kjell-G and others have an opposing opinion on the merits of replacing electrolytics and, I must confess, I was biased towards the "if it ain't broke ... " camp but you, Glenn and others have moved my butt over into the "should be replaced if over 10-15 years old" camp.

I think that Kjell-G and a few others are having a difficult time separating the science of these devices and the sound quality that a vinatge unit exhibits in state "A" vs. state "B"; A=original caps and B=replaced with modern caps.

The problem with that argument, in my opinion, is that the quality of sound is virtually 100% subjective and often is judged without the necessary sicentific controls in place to filter out subjective opinions.

Anyway, gentlemen, continue with the discussion and educattion. This may become the best thought out thread we've ever had. :thmbsp:

Paul

We have now come to the point of repeated statements and little new. There is no science involved in statements like: capacitance + ESR + leakage determines the sound of a capacitor. So what is sound ? A very complex term. Yes ESR is a scientific based term (because it is so simple to define), but in what way is it related to "sound" ? To state that ESR is related to sound is objective nonsense.

And what is the optimum ESR in a vintage circuit if the original sound is to preserved ? No one could answer.

I cannot see any consensus on the tech statements. Of course the tech people themselves have come to a consensus of their own. And owners of heavily recapped amps would like to have the confirmation that they did the right thing. From my knowledge on discussions like this, most people would retract from participating as "ignorants" by the "scientists" here.

Why should it be necessary to prove anything. Sound quality is such a complex and difficult parameter that no one can prove much useful.

I have soldered thousands of components in and out of vintage and high end equipment. It is very easy to hear the sound changes - and that is my main reason for posting in this thread. Do not believe the "experts", instead learn how to use a soldering iron and try for yourself. No proofs. Just listen. So my main case is: It is not possible to build a good hifi system by reading objective analyses by technical experts. Listening experience is what counts.

Known physical parameters are very important in new designs, but for us vintage enthusiasts the most important thing is to listen to as much different equipment as possible and discuss with other enthusiasts who have the same attitude. A forum like Audiokarma is well suited, but beware of the angry engineer. :nono:

 

[pustelniakr]

We have now come to the point of repeated statements and little new. There is no science involved in statements like: capacitance + ESR + leakage determines the sound of a capacitor. So what is sound ? A very complex term. Yes ESR is a scientific based term (because it is so simple to define), but in what way is it related to "sound" ? To state that ESR is related to sound is objective nonsense.

And what is the optimum ESR in a vintage circuit if the original sound is to preserved ? No one could answer.

I cannot see any consensus on the tech statements. Of course the tech people themselves have come to a consensus of their own. And owners of heavily recapped amps would like to have the confirmation that they did the right thing. From my knowledge on discussions like this, most people would retract from participating as "ignorants" by the "scientists" here.

Why should it be necessary to prove anything. Sound quality is such a complex and difficult parameter that no one can prove much useful.

I have soldered thousands of components in and out of vintage and high end equipment. It is very easy to hear the sound changes - and that is my main reason for posting in this thread. Do not believe the "experts", instead learn how to use a soldering iron and try for yourself. No proofs. Just listen. So my main case is: It is not possible to build a good hifi system by reading objective analyses by technical experts. Listening experience is what counts.

Known physical parameters are very important in new designs, but for us vintage enthusiasts the most important thing is to listen to as much different equipment as possible and discuss with other enthusiasts who have the same attitude. A forum like Audiokarma is well suited, but beware of the angry engineer. :nono:

Beware of accusing folks with long standing track records in improving the sound of vintage equipment of selling snake oil and whipping up false frenzy in order to take advantage of unwitting folks. Beware of accusing folks who do good things for people, at 1/10th the going rate for such work, of not having an ear to notice if the sound or measureable performance improved, especially when backed up by their customers' testimonies. Beware of accusing forlks with hundreds of pieces of vintage gear passing over their benches successfully, that they have nothing to to offer but scientific BS. Yes. You stick you finger in my eye and I will squawk. If you do it in another thread, I will sqwawk there to. I started working on this gear back when it was new (1976). Practical experience? I have it. Scientific experience to back my claims? I have it. And I have posted it here. I have my own ears to listen with. Satisfied customers with testimonies that the sound quality improved after I was done? I have dozens, many of which are on this board. Find yourself one of my customers that is dissatisfied...in ANY way.

No you don't. Yes I do. No you don't. Yes I do. No you don't. Yes I do...Sounds like a urination contest to me.

Listen....You want to keep your caps? Keep them. What is it to me? I have previously defended your right to do so, and your motivation to do so. You like vintage caps, proven caps, superior caps? I have thousands of them in bags, labelled with the model and serial number of the units they came from. I'm sitting on a gold-mine here. And I ripped off my customers to the tune of $0.75 per hour to swap them out. Maybe you can do my customers a great favor and put them back in.

Whew! Did I say that out loud?

(Notice: Putting a cute little smiley on the end of such stuff, does not make it more palatable, or true)

Enjoy,
Rich P

 

[restorer-john]

If I never saw another leaking, open, short or blown apart electro, I'd be a happy man- it'd give me more time to replace all the carbon resistors and the mismatched gain transistors, but for the time being, until we get a 'perfect' cap that has a proven long term life- in other words, longer than the working ones I am taking out, I'll stick to fixing what needs fixing, not unecessarily removing and placing undue stress of ancient pcbs, dodgy wire wrap terminals, poorly ahdered copper tracks, numerous brittle multiway connectors and the like. It's funny to keep reading the unecessary failures caused to otherwise working equipment by test probes 'slipping' poking around trying to adjust the last millivolt of offset. To keep bringing up the bully mentality in an attempt to 'convert' people into mindless followers is not really in the spirit of a discussion is it?
I see it from all points of view but subscribe to one or two, others subscribe to a different policy for replacement/sound etc . That's OK, as no-one is right or wrong here, just different. What everyone agrees on however is that if a cap is faulty, you replace it with the best one you can afford or justify in its place. :thmbsp:

 

[restorer-john]

Want some evidence?

Attached are some pics taken of about 20 NEW caps (nichicon and rubycon) still on their looms with serious electrolyte leakage. These were bought new by me about 6 years ago but stored in my cool electronics room in drawers. Evidence that new (as in recent good quality japanese caps), UNUSED can and do fail in less than a decade. I just tipped out a shoebox full of old 1970s half used/half new electrolytic caps and there is not one leaked capacitor in there. Seriously guys, think about it.:scratch2:

 

[QuadBob]

Beware of accusing folks with long standing track records in improving the sound of vintage equipment of selling snake oil and whipping up false frenzy in order to take advantage of unwitting folks. Beware of accusing folks who do good things for people, at 1/10th the going rate for such work, of not having an ear to notice if the sound or measureable performance improved, especially when backed up by their customers' testimonies. Beware of accusing forlks with hundreds of pieces of vintage gear passing over their benches successfully, that they have nothing to to offer but scientific BS. Yes. You stick you finger in my eye and I will squawk. If you do it in another thread, I will sqwawk there to. I started working on this gear back when it was new (1976). Practical experience? I have it. Scientific experience to back my claims? I have it. And I have posted it here. I have my own ears to listen with. Satisfied customers with testimonies that the sound quality improved after I was done? I have dozens, many of which are on this board. Find yourself one of my customers that is dissatisfied...in ANY way.

No you don't. Yes I do. No you don't. Yes I do. No you don't. Yes I do...Sounds like a urination contest to me.

Listen....You want to keep your caps? Keep them. What is it to me? I have previously defended your right to do so, and your motivation to do so. You like vintage caps, proven caps, superior caps? I have thousands of them in bags, labelled with the model and serial number of the units they came from. I'm sitting on a gold-mine here. And I ripped off my customers to the tune of $0.75 per hour to swap them out. Maybe you can do my customers a great favor and put them back in.

Whew! Did I say that out loud?

(Notice: Putting a cute little smiley on the end of such stuff, does not make it more palatable, or true)

Enjoy,
Rich P

Damn Rich!

I was almost ready to waste another hour trying to be civil......citing that I NEVER referred to Krell-B as "ignorant"........simply of choosing to ignore the science and evidence as found in OUR equipment everyday now.

But, you've said it pretty damn well.:thmbsp:

I guess I can only add that I have a pretty damn demanding "day" job trying to keep X-ray machines on-line and running.........so my "Sansui" passion is relegated strictly to my "fun" time. I consider helping others like myself that are passionate about their audio equipment "fun" and THAT makes it worthwhile for me. Even my wife has come to refer to the phone calls I get after someone has their freshly restored piece back home as just another "WoW" call!

So, hey.........I'm just a guy that has been through 60 of the EXACT SAME model from start to finish over the last 15 years, everyone of which is STILL being listened to daily and almost none of which has had any failure since restoration nor even needed their controls cleaned.........what would I know about any of this!

I treat my audio restorations and repairs just like I treat my Xray machines....my goal is to be the "Maytag" man, I'd prefer not to have to fix it at all.........and when I have to, I only want to do it ONCE!

QB

 

[spaceman]

That's kinda interesting, but doesn't that fall into the category of a bad batch, & not normal? Or possibly they were exposed to temp extremes or something, before you ever got them, maybe during shipping? :scratch2:

 

[QuadBob]

All electrolytic caps MAY be subject to evaporation... is a more correct statement and certainly still not a fact. To date, your experience and numerous others anecodatal muses are still not FACT.

John,

Your argument isn't with me........you might want to contact Nichicon, Panasonic or any of the other electrolytic cap manufacturer's. THEY'VE convinced me.........once again I refer to THEIR chart and analysis!

Not only that, the vent can be described as a last resort protection for the cap to prevent a catastrophic failure. A cap expanding and contracting and venting as you described is not stable. It is about to fail. Any cap with any bulging or evidence of venting should be replaced in my opinion, regardless of its measured value.

We all know caps leak, we all know they dry out, we all know batches can be bad (I did a Quad34 preamp where every identical value/identical batch cap had leaked and eaten the PCB, but all the others were fine)

So here we agree.................I guess this just means that they CAN cause problems!

The subject was about power supply caps, not coupling or any other caps. As usual, the thread gets polarized into a old vs new, recap vs not thread with all the usual suspects weighing in. I seriously think capacitors are getting the same level of snake oil all over them that cables have attracted.

Not sure where you're going with this.......... the physical properties of all electrolytic capacitors is the same regardless of application.

As to "snake oil".........if you're speaking of modern "exotic" electrolytic caps I probably agree, but it doesn't mean that I ignore the basics.

There is no doubt restorers like us could do without the problem, but it is going to be an endless source of trouble for years to come.

Not for me........at least for many more years. Audio gear I restore doesn't end up BACK on my bench.........nor on anyone elses. And, while you could say that is certainly "subjective" it has held true for over 10 years and in excess of 300 units!

It's a discussion that always goes the same way, because if all the capacitors in our vintage equipment lasted as long as their rated life and adhered to the manufacturers MTBF data, the old gear would have been in the landfill 15 years ago with 100% failures. It didn't fail and now the problem is, do you replace PROVEN caps with a life greatly in excess of their ratings with new products with no such proven life?

You might want to check those landfills John..........because based upon what we can tell from production quantities vs. what we see here in the Sansui database or on Ebay...........a WHOLE LOT of this equipment went somewhere!

As to "proven life".............Mark the date, with a little luck I'll be around in 15 years..........so I'll get back to you then on how MY Sansui equipment is doing!:thmbsp: Where were you in 1992 when I recapped my first QRX-9001?

There is no one outcome here and never will be as you guys will be replacing today's replacement capacitors in 10 years when some of the old 1970's ones are still working as they did 30 years before.

From the trends I've seen over the last 5 years........this one won't be much of an issue........the next great debate is whether you want to replace 100% of the small signal transistors and ICs..........their failure rate is WAY up on my bench on the units arriving now.

It's all fun anyway, until the brown goo the Japanese used eats up a PSU electro's lead and the whole amp goes up like a flashbulb.:thmbsp:

Total agreement there........it's ugly, and is only getting worse! So much for keeping it "original"!!

QB

 

[restorer-john]

Hey spaceman, three different values and voltages, two different manufacturers. Have a look at the photos.The only thing common is their age- modern caps...

 

[EchoWars]

I say we lynch the little buggers...damn their useless black electrolytic hearts...

Hundreds of thousands of caps are made each year, and I doubt what you have represents 1/2 of 0.000000000000000000000001% of the industry total. Hardly a valid representative sample, and certainly not enough to issue an indictment on the industry as a whole. I will tell you this...those caps are not intended to sit in those glued paper spools for years on end. I suspect some reaction with the glue and the leads (that's a WAG, if you couldn't tell).

5 or 6 years ago, Chinese (Taiwan) cap manufacturers got caught in some industrial espionage that resulted a bazillions of bad electrolytic capacitors making their way into bazillions of computer motherboards. Caused havoc in the industry for years that is only now relenting (I must have changed out 30 motherboards, and swapped caps on 20 of them when downtime was not an option). All the caps were Chinese...the Japanese escaped the whole issue. I buy only Japanese parts.

What does all that mean? Fark...I dunno.

 

[QuadBob]

I say we lynch the little buggers...damn their useless black electrolytic hearts...

Hundreds of thousands of caps are made each year, and I doubt what you have represents 1/2 of 0.000000000000000000000001% of the industry total. Hardly a valid representative sample, and certainly not enough to issue an indictment on the industry as a whole. I will tell you this...those caps are not intended to sit in those glued paper spools for years on end. I suspect some reaction with the glue and the leads (that's a WAG, if you couldn't tell).

5 or 6 years ago, Chinese (Taiwan) cap manufacturers got caught in some industrial espionage that resulted a bazillions of bad electrolytic capacitors making their way into bazillions of computer motherboards. Caused havoc in the industry for years that is only now relenting (I must have changed out 30 motherboards, and swapped caps on 20 of them when downtime was not an option). All the caps were Chinese...the Japanese escaped the whole issue. I buy only Japanese parts.

What does all that mean? Fark...I dunno.

Totally agree Glenn........so many years ago when I first started trying to analyze how to keep my beloved QRX-999 "alive" so that I could finally enjoy owning one........and I realized what changing out 264 electrolytic capacitors in one receiver really entailed..........my only thought was that I probably only needed to do it ONCE for me!

Now 60 QRX-9001's which adds up to 15,840 caps later........I can count on one hand how many of them have failed, all of which died on the bench when I let some guy get distracted and put them in backwards!!:tears:

All total........I've probably changed out over 25,000 electrolytic caps in all the units I've restored..........and again, known failures.......the 3 or 4 I screwed up!

But, I do remember the pc motherboard incident you speak of in Taiwan, and in my earlier post where I cited the Nuclear Regulatory Agencies investigation...those were Sprague caps that were only around 5 years old. So, manufacturing defects do happen now...........and I bet if anyone looked hard enough, they happened in the '70s as well!

Now if we could just track down the Sansui Engineer who said "pass-through" joints are the way to go to cram more runs on a pcb...............we could stand him up next to the "glue" salesman and shoot them both!!!!!!:thumbsdn:

QB

 

[Kjell-B]

Attached are some pics taken of about 20 NEW caps (nichicon and rubycon) still on their looms with serious electrolyte leakage. These were bought new by me about 6 years ago but stored in my cool electronics room in drawers. Evidence that new (as in recent good quality japanese caps), UNUSED can and do fail in less than a decade. I just tipped out a shoebox full of old 1970s half used/half new electrolytic caps and there is not one leaked capacitor in there. Seriously guys, think about it.:scratch2:

Thank you for your very important information.

This is in accordance with my own experiences. As I said earlier, my quite large tube preamp was built (by myself around 1990) using 40-60 years old radio parts including OLD electrolytic capacitors. No capacitor has ever failed since. This is possible if you know the good brands.

I have a large collection of old capacitors (the good brands) - when I test them, they are still all good.

European capacitors were very reliable in the years 1950-70 (and some even earlier), and the better Japanese capacitors continued this good behaviour 1970-80.

US capacitors were never good (long-term reliable) in my hands (and my limited experience), and electrolytic capacitors were generally less reliable after 1980 (I had to repair most of my VCR's and TV sets for that reason).

I continue to use the old capacitors and can live happily with that. Good reliability and no change of sound quality in my equipment. They may perhaps last 500 years.

 

[EchoWars]

So, I can call you up for my next large capacitor order then?

If the answer is 'no', then your point is still a nonsensical one, as I continue to need large quantities of caps since I keep finding bad ones. The fact that you have managed to find a few caps that have lasted 50 years does not render everyone elses point moot. The parts you have found are the exception, not the rule.

 

[Kjell-B]

To summarize my ideas here:
I think it is a good idea to change caps in stressed positions, like the big PSU caps, especially in larger power amps. And there may be difficulties in finding large vintage caps; so then a new production large PSU cap should be installed.

What I criticize, is:

1. The selection of new caps without serious listening tests to check sound quality

2. The uncritical removement of all old caps just for the reason of easy repair (checking each cap is time-consuming)

3. The use of "scientific proofs" to justify these extensive restorations to potential customers.

I would have liked a discussion around large PSU caps - if we have to use new production, what are the better brands to be used in vintage equipment ?
I have myself collected samples of new large capacitors (produced 2006) that I will test in a nice old AC-coupled Tandberg receiver (Tandberg used very good caps) and report here.

 

[Morden2004]

One more factor ...

There is one more factor that I don't recall seeing during this excellent discussion -- and one that I thought was germane to the problem of aging electrolytics; that is the nature of the chemical reaction in an electrolytic that MAKES it a capacitor.

Remember, an electrolytics are just two metal plates with an electrolyte between them. It doesn't begin to be an effective capacitor until it has current applied and the magic happens. Read on:

Aluminium electrolytic capacitors, in common with batteries, work by chemical action and, like batteries, tend to deteriorate with age. The capacitor itself consists of two aluminium foils separated with an absorbent material soaked with an electrolyte. During manufacture a current is passed through the electrolyte, forming a very thin oxide coating on the positive foil. This process is known as "forming" - and is precisely what you are doing when reforming a long disused but otherwise serviceable capacitor. The conductive electrolyte becomes the negative electrode with the negative foil simply serving to make connection to it. The oxide film acts as the dielectric and it is the extreme thinness that enables very large capacitance to be packed in so small a physical size.

In all electrolytic capacitors likely to be encountered in vintage radios, the electrolyte is a solution of one or more chemicals in water, and no matter how well the component is sealed the water content will eventually dry out over the years. This causes the electrical resistance of the electrolyte to rise, increasing the equivalent series resistance (ESR) of the capacitor until eventually it becomes effectively open circuit. This process is not only age-related but depends on the operating conditions, particularly ambient temperature.

The small leakage current exhibited by aluminium electrolytics may be a nuisance but is a necessary evil as it maintains the oxide film. Running an electrolytic capacitor at a small fraction of its maximum working voltage can cause deterioration of the dielectric film, resulting in loss of capacitance or even total failure. Aluminium electrolytics are happiest when worked at around 75% of their maximum voltage. Many old transistor radios use low value capacitors rated at 50 volts or more, as coupling capacitors often with only a volt or so across them and in such cases it may be preferable to use a tantalum bead part for a replacement. Tantalum caps aren't so fussy over being run at very low applied voltage. The reason high voltage capacitors are found in old transistor radios was the manufacturers' desire to use as far as possible, a common inventory for both transistor and valve radio lines. I do stock brand new tantalum caps but they are unsorted: let me know what values you need and I'll find them for you.

Connecting an electrolytic capacitor the wrong way round, or applying raw AC across it without any DC polarising voltage, will rapidly break down the dielectric film. This results in a heavy current flow leading to internal heating and production of gas. Internal pressure builds up until the bung is blown out or the can ruptures explosively, both of which are extremely hazardous. So-called "non polarised" electrolytics actually contain two capacitors wired back-to-back inside one can. Their power factor is awful, and in most applications that need such a capacitor, such as motor starting, they are rated for intermittent duty only. The only place you'll find them in brown goods is in speaker crossover networks.

The key statement is

During manufacture a current is passed through the electrolyte, forming a very thin oxide coating on the positive foil. This process is known as "forming" - and is precisely what you are doing when reforming a long disused but otherwise serviceable capacitor.

and if I recall my college courses correctly, an electrolytic capacitor which is many moons distant from it's initial forming needs to be reformed before rejoining the world as a working capacitor. That means that it shouldn't be hit with working voltages initially, but 'formed' with a slowly increasing voltage -- over time. That means that when I restart a vintage unit on my 'poor mans variac' I am actually reforming those old electrolytics and that is one of the key factors I want to inject into the discussion.

See, I'm not just another pretty face!

Paul

 

[Kjell-B]

The key statement is and if I recall my college courses correctly, an electrolytic capacitor which is many moons distant from it's initial forming needs to be reformed before rejoining the world as a working capacitor. That means that it shouldn't be hit with working voltages initially, but 'formed' with a slowly increasing voltage -- over time. That means that when I restart a vintage unit on my 'poor mans variac' I am actually reforming those old electrolytics and that is one of the key factors I want to inject into the discussion.

See, I'm not just another pretty face!

Paul

Yes, that is quite important with old equipment stored for many years without being used. During restart the leak current is high - I once (with full line voltage) discovered that a fuse blew because of this leak. However, I did not replace the cap, instead I replaced the fuse, let the power on for short periods only the first day, and the cap cured itself, and has worked perfect since. A variac is even better here.

It is possible that many recaps could have been avoided if people knew this.

 

[Crazy]

Well...........

I've been a bit wiser than some here as I've taken time to do some fishing & beer drinking & bar-b-qing for a couple days.:thmbsp:

I've let much digest........:yes:

At first I was of the " if it ain't broke don't screw with it" way of thinking........

Then I was swayed more toward the " now I'm paranoid and maybe I better do preventive things to avoid meltdown"...............

But to be truthful............I've learned a lot from this thread.........I HAVE considered both sides "impartially".

Both sides have their strong points and evidence. Some mindsets are.......well .....set in concrete. Some are more open. Some seem to be getting mad..........others take it for what it is.........a "DEBATE" with the purpose to pose new modes of thinking and to "LEARN".

Again...........GREAT THREAD!........Thanks to all for time spent.

But ya know..........one point still keeps sticking in my head.

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:

Again.........for kicks............I'm going to recap my 881 or 771 completely ( myself)..........the others..............NADA!:yes:

It may take years...........or months.........or they may never die??? We shall see.

But folks I'm squarely back in the "don't screw with it if it ain't broke" club again.

WHY??????????

COMMON SENSE, IMHO, outweighs science time and again through life.

EVERYDAY.

Science has it's place............but only used with "common sense". :yes:

Well.............. back to that Bar-B-Q and cold beer!

I shall continue to follow the thread.

AND........a special thanks to all those who exhibit common sense. :thmbsp:

 

[spaceman]

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: After all, as most of us here SHOULD know by know, that's what Sansui started out doing. Obviously, there's a lot more to it than that, the "topology" has to figure in. That's pretty obvious, because you can hear a difference between models, especially between (for example) my 7000 & my 881. Or maybe they started making the transformers a little differently around that time?

 

[restorer-john]

The trouble with those failures is the 100uF Rubycons and Nichicons measure fine, both capacitance and ESR, but you can imagine what that leaking electrolyte would be doing to the PCB and solder right now if they were mounted. The larger value rubycons are down to 10% of their capacitance. The thing is, I have hundreds of brand new Japanese caps bought in the late 90's and from 2000 on for replacing in vintage gear. I know for a fact I have used many of those caps in pieces I have restored. Makes me seriously question the life of the new caps- that's all.

 

[Crazy]

I think the transformer is only power. The circuitry likely have the most effect on "the sound".

It does amaze me what huge power supplies are in the Sansuis I have.