50 year old amps

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Online window shopping as you do and I came across a lovely looking Sansui AU8500.

Various questions asked of the seller, particularly around capacitors and transistors. I'm told that a couple of small power supply caps were replaced and that all other capacitors and transistors are in perfect condition - apparently it's been hardly used and kept in a glass case. Good for another 50 years I'm told.

Does that sound likely to the good people of the wam?

Meanwhile, you snooze and you lose, the amp has been bought by someone else. Still, be useful to know if people think barely used capacitors can still be good after 50 years....
 
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one way to find out - run 'em up slowly on a variac, watching 'em closely - any sign of trouble, pull the plug instantly
Not much help to me as I have no idea what a variac is or how to remove caps from an amp to do this!

Question was much more general than how to actually carry out tests.

Is it likely, in your opinion, a 50 year old capacitor could still be good for some time?
 
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audio_PHIL_e

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Is it likely, in your opinion, a 50 year old capacitor could still be good for some time?
I'm not skilled enough to say. I have a Selmer Treble'n'Bass 50SV amplifier (probably dating from 1975) that I checked over a year or two ago, and none of its caps were giving any trouble. If you want a better answer, I suggest contacting a variety of amplifier repair shops - some of who will tell you to "bring it in" so that they can have a look, some will tell you "yes, replace all the electrolytics to be on the safe side" because they want to get paid for it, and others might say "don't waste your money or our time", and it'll be your choice as to who you believe. I would be likely to trust people like @rabski or @toprepairman.

PS to put your amplifier on a variac doesn't require you to remove the caps from it.
 

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I'm not skilled enough to say. I have a Selmer Treble'n'Bass 50SV amplifier (probably dating from 1975) that I checked over a year or two ago, and none of its caps were giving any trouble. If you want a better answer, I suggest contacting a variety of amplifier repair shops - some of who will tell you to "bring it in" so that they can have a look, some will tell you "yes, replace all the electrolytics to be on the safe side" because they want to get paid for it, and others might say "don't waste your money or our time", and it'll be your choice as to who you believe. I would be likely to trust people like @rabski or @toprepairman.

PS to put your amplifier on a variac doesn't require you to remove the caps from it.
Thanks, a very useful answer. Kind of what I was thinking underneath the haze of not being certain and missing out.

Perhaps the best thing may have been to buy and listen, then if problems presented get it repaired.

Bit gutted I missed out on the AU8500, sounds like I ought to have trusted the seller's comments from his engineer and taken the plunge. It was a gorgeous looking amp that had all the things I needed e.g. tape out, two speaker set connections (actually three), bass - mid - treble adjustments.
 

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The rule with amps is to service every 10 years. I have a 25-year-old amp which deteriorated slowly after about 10 years and packed up in 2020 after 22 years of daily use.
It came back after 8 months in repair sounding sublime.
It took him this long because there was so much that needed replacing. Fortunately, though the transformers were good as this is the biggest expense in most amps.
I always view a second-hand amp with the necessity of spending something on servicing.
The positive in doing this is if you know a good electronic engineer it will come back better than anything that can be bought for sensible money nowadays.
These older high-end amplifiers were seriously well made and will outperform most stuff nowadays in IMO.
 

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The rule with amps is to service every 10 years. I have a 25-year-old amp which deteriorated slowly after about 10 years and packed up in 2020 after 22 years of daily use.
It came back after 8 months in repair sounding sublime.
It took him this long because there was so much that needed replacing. Fortunately, though the transformers were good as this is the biggest expense in most amps.
I always view a second-hand amp with the necessity of spending something on servicing.
The positive in doing this is if you know a good electronic engineer it will come back better than anything that can be bought for sensible money nowadays.
These older high-end amplifiers were seriously well made and will outperform most stuff nowadays in IMO.
The ten year rule sounds practical. As does factoring in a service with second hand amps.

Now someone who knows far more will tell us amps can run for fifty years and ought to be left alone until problems appear 😂
 
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Juancho

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Well, I would say it depends on the amp. I serviced an old Sansui amp recently and all the caps measured and worked perfectly. Nonetheless the owner wanted the caps changed so changed they were.
I would say changing caps every 10 years is excessive unless it's an amp that runs very hot
 

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The ten year rule sounds practical. As does factoring in a service with second hand amps.

Now someone who knows far more will tell us amps can run for fifty years and ought to be left alone until problems appear 😂
Yes, the guy selling it!
I was lucky to find a guy that was a Roksan amplifier engineer for a long time. I dropped it off at his place and he had everything from Mcintosh, Bryston, Electrocopaniet etc, all about the same age as mine in for repair.
He talked me through various stages of the fix, as there was so much and I was interested.
After having it back in my system for a month, I rang him to tell him how impressed I was with the sound it was making.
He told me it was the most difficult fix he had ever worked on and the most complicated design.
He charged me his standard £500 fee and hand on heart I would have to spend between 5 to 10k to come close to its sound quality and copious amounts of power it can deliver into a speaker.
Some of these amps from the past can't be surpassed if looked after regularly. Why I don't really know, but my guess is it's something to do with the difference in comparative quality and cost of components, then and now.
 

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Yes, the guy selling it!
I was lucky to find a guy that was a Roksan amplifier engineer for a long time. I dropped it off at his place and he had everything from Mcintosh, Bryston, Electrocopaniet etc, all about the same age as mine in for repair.
He talked me through various stages of the fix, as there was so much and I was interested.
After having it back in my system for a month, I rang him to tell him how impressed I was with the sound it was making.
He told me it was the most difficult fix he had ever worked on and the most complicated design.
He charged me his standard £500 fee and hand on heart I would have to spend between 5 to 10k to come close to its sound quality and copious amounts of power it can deliver into a speaker.
Some of these amps from the past can't be surpassed if looked after regularly. Why I don't really know, but my guess is it's something to do with the difference in comparative quality and cost of components, then and now.
The main problem I see is the transistors both output and drivers may be next to impossible to replace. Also if the switch gear plays up beyond what a good strip and clean will cure
 

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Well, I would say it depends on the amp. I serviced an old Sansui amp recently and all the caps measured and worked perfectly. Nonetheless the owner wanted the caps changed so changed they were.
I would say changing caps every 10 years is excessive unless it's an amp that runs very hot
That's interesting. I had the impression the seller of the AU8500 was genuine and trusted in his engineer: he did say all cold joints had been sorted and a couple of small caps replaced. 100% positive feedback with around 500 sales backed that up.

I guess - if taking time to send off for service - getting all caps replaced can make sense as theoretically it gives the owner some assurance it'll be some time before another service is required.

Kind of "while I'm here I may as well take one of them as well".

Regret not taking the plunge but there's always another time.
 
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oldius

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I have two amplifiers from the late 1970s: The Lentek and a Denon PMA850. As standard, I had them fully recapped and serviced when I bought them. We are now several years in and they have given faultless service, bar a small problem with a transistor channel in The Lentek. In some ways, we are custodians of this kind of kit: it was very expensive at a time when my family had a Reliant Supervan as my dad's work van and our family car; we could not have afforded such luxury items. Also, having owned amplifiers worth several thousand pounds and kept these two, I know their quality, and they'll be with me for as long as they work.
 

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Electronic equipment is not like cars. You service a car at regular intervals either by time or mileage, because cars are in damp conditions much of the time and even if not used, some fluids (brake fluid notably) are hygroscopic, things need lubrication and oil chemically degrades.

I personally do not like the word 'service' applied to electronic equipment. I also have to say that I do not agree with the ten year 'rule'. Basically, it's a lottery. However, the vast majority of capacitor failures are not drastic, but become apparent through increased hum and decreased performance.
 

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However, the vast majority of capacitor failures are not drastic, but become apparent through increased hum and decreased performance.
This is what happened to my amp. The sound softened and the detail fell off to negatively affect the system as a whole. Having been through this experience It does make sense to me to check things out over time if the amp is a keeper. I did leave it for 22 years though...before it shut down.
 
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rabski

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This is what happened to my amp. The sound softened and the detail fell off to negatively affect the system as a whole. Having been through this experience It does make sense to me to check things out over time if the amp is a keeper. I did leave it for 22 years though...before it shut down.
It's finding someone decent who isn't overrun with work, unless you DIY.

Far too many 'repairers' just look at the age and unnecessarily replace all and sundry, often in the process upgrading things that shouldn't be upgraded and actually making it reliable, but worse sounding.
 

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It's finding someone decent who isn't overrun with work, unless you DIY.

Far too many 'repairers' just look at the age and unnecessarily replace all and sundry, often in the process upgrading things that shouldn't be upgraded and actually making it reliable, but worse sounding.
Yes I feel very lucky to have found my engineer. I know it can be a lottery.
 
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Its quite possible that caps are OK after 50 years, but they could go pop at any moment. It also depends on how they're stressed and the function they serve - some caps, if they go e.g. short circuit, will kill an amp, others are less critical.
Only way to tell is to take it to a someone knowledgeable and have them go through the amp. Henry (toprepairman) looked at my Quad IIs/22, replaced some caps but others were OK even after 60 years. Of course, those original caps could go pop at any time...in fact one did and was lucky I caught it.
The caps in the 22 and FM1 tuner were fine, nothing weas touched. It tends to be caps in the power department that are the ones to watch.
 

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Seems to be pros and cons to all approaches. Indeed a lottery.

Twist and risk unnecessary expense, and perhaps worse sound.

Or twist and avoid risk of a cap popping,

Stick and the chances of a cap going pop increase.

Or stick and save money, and retain the original sound.

Thanks for all the useful replies all.
 

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