There is no general answer to that.
High-quality elcap models (mostly those with screw terminals) are still in excellent condition even after a very long time (check out the blue cans from FTcap in first images from post #7 under
https://www.diyaudio.com/community/...amplifier-ca-25-ca25-schematic-wanted.160949/
while others - most cost-effective versions with small CV product have already become unusable after a small number of operating hours like one in post 28 under
https://www.diyaudio.com/community/...ier-ca-25-ca25-schematic-wanted.160949/page-2
(first, fifth and sixth image) check also out keyword for Google: "Bad Caps"
I replace in general in cases as follow (by brands known for good quality like Panasonic, Nichicon, SicSafco etc.):
- thermal stress
- low voltage versions (3V, 6V, 10V, 16V and 25V I always replace by 63V or 50V versions).
- all brands known to leak or dry out
- all brands that were already bad when new
I kept all defective electrolytic capacitors from my repairs from around 1975 to 2010 (unfortunately, I have thrown them all away in the meantime) - this way I knew over the years in any cases, which electrolytic capacitors always needed to be replaced and which ones didn't need to be replaced.
Replacing electrolytic capacitors with new ones is surprisingly much less likely in devices from the 1970s than in devices from later years. Some Elcaps from Siemens like those under
https://www.ebay.de/itm/23511336196...MIhO3SsLfmgAMVGJSDBx3EFwxiEAQYAyABEgJW_vD_BwE
used in 60-65 years old tube radio stuff always in nearly perfect condition.
ckeck also out post #2234 under
https://www.diyaudio.com/community/threads/best-electrolytic-capacitors.151392/page-112
and the mentioned URLs there.
These is a caveat - if the device has any capacitor plague caps (see badcaps.net), definitely replace them. Such a device has probably long since had caps leak all over the PCB and cause havoc though! Alas there are still bad caps around, avoid cheap unknown brands and don't buy caps on eBay unless you know the supplier is trustworthy.
I've been working on amps for over 50 years, both professionally and as a hobby. It wasn't until the market was flooded with fake caps in the mid 2000s that anyone thought of recapping. Then it became a necessity as equipment was failing within months of being released. Otherwise if there is a fault or an amp has had a rough life treat it as a repair. Like previous posts I have amps going back many years and they are fine. I could update the caps and get a different sound but I keep them for what they are and the sound they produce.
Absolutely right.
check out this URLs and pdf attachment
https://www.researchgate.net/figure...he-red-rectangle-The-capacitor_fig1_262772064
https://www.electronicproducts.com/how-to-spot-counterfeit-passive-components/
check out this URLs and pdf attachment
https://www.researchgate.net/figure...he-red-rectangle-The-capacitor_fig1_262772064
https://www.electronicproducts.com/how-to-spot-counterfeit-passive-components/
Attachments
I've seen that fakery with the small one in the large case for D-cell NiMH rechargable batteries - an AA inside a D-cell case. I didn't kind so much charging more often, the real problem was with vibration as they fell apart in weeks in a bicycle light! I changed to 10Ah Ansmann D-cells - heavy, but reliable!
I would say that it's very likely that newer components have been dumbed-down at every level to lower costs and improve profitability. I find it hard to think of any product which is more solidly built and/or designed to last longer than one made twenty or thirty years ago.
Recapping, for the most part, I've done has been due to age.
I have recapped a 1957 radio, as a result the buzz and noise level dropped so those tar caps were leaking.. The A220 got recapped because it blew a rectifier bridge and fuse where the caps, after 24 years, were effectively causing large current peaks. The CDP got 35 electrolytics recapped as that really had a problem maintaining the VFD and the draw system was playing up.
Fancy film caps? I'm not sure WIMA caps are fancy..
I have recapped a 1957 radio, as a result the buzz and noise level dropped so those tar caps were leaking.. The A220 got recapped because it blew a rectifier bridge and fuse where the caps, after 24 years, were effectively causing large current peaks. The CDP got 35 electrolytics recapped as that really had a problem maintaining the VFD and the draw system was playing up.
Fancy film caps? I'm not sure WIMA caps are fancy..
If you already have the cover off for a repair & items can be got to easily might as well "re-cap" a few whilst you're there......is what I go by......😎.......& thus the "quick 5min job" snowballs into a full blown strip down!!!.....🤣
And the full strip down often results in a non working amplifier, taking even more time to correct. You don’t fix what isn’t broken. You replace caps which have actually failed or degraded (ie, your amp’s not putting out full power at low frequency, so the reservoirs are bad), anything at high risk of failure due to age/type (ie, FP cans in 50 year old amps), or ones that are known to give trouble in similar circuits (ie, the Phase Linear bootstrap cap, the protect relay timing cap in the big Crests). Most of the time caps do not need to be changed. You could very well have 10 or 20 ohms of ESR in a signal coupling cap, but in a 20k ohm circuit who gives a f***? Many times normal degradation is totally invisible and it may as well be left alone. To see any effect you need really good (and expensive) test equipment and presumably you’d know enough about what you’re doing not to wreck the amp.
For every used piece of equipment that I obtain, I will test each electrolytic capacitor in circuit with an ESR (equivalent series resistance) meter. It has tweezers that let me touch the leads without de-soldering and then it will run an auto test at a high frequency and read the ESR along a scale of capacitor values in uF. If ESR is high or marginal then I will replace those capacitors. So many modern surface mount electrolytics test bad these days.
My first experience with replacing electrolytic capacitors was while I was in college in the Nashville, TN area. Somebody who owed the legal system some community service hours kindly offered to re-cap our university's studio console. The studio had a 16 track MCI multitrack tape recorder and a Harrison console. I'd done lots of recording sessions on that console before and after the re-cap and the difference was amazing. We picked up at least an extra octave in the low frequencies. The noise level and distortion went down and the transients seemed to pop better on things like snare drums. It was like having a new console.
Years later, I found a small(ish) Neve console at a TV station that had spent most of its life sitting in a remote broadcast van parked in the hot tropical sun for years on end. I was able to make an offer and buy it for a reasonable price. It's coupling capacitors had degraded and leaked DC through making for lots of DC offset hitting the switches and the pots. It needed a whole re-cap. But it was amazing afterwards. I flipped it for a good profit before I even refurbished it but I had sellers remorse after that because it sounded so good when the work was done. It took at least three people to even pick it up to carry it.
I find that heat really wastes electrolytic capacitors quicky. The familiar switch mode power supply modules often have electrolytics packed tightly near to a heat sinked voltage regulator that will slowly cook it and noise comes through with the degradation. I've come to regard electrolytic capacitors as consumables.
My first experience with replacing electrolytic capacitors was while I was in college in the Nashville, TN area. Somebody who owed the legal system some community service hours kindly offered to re-cap our university's studio console. The studio had a 16 track MCI multitrack tape recorder and a Harrison console. I'd done lots of recording sessions on that console before and after the re-cap and the difference was amazing. We picked up at least an extra octave in the low frequencies. The noise level and distortion went down and the transients seemed to pop better on things like snare drums. It was like having a new console.
Years later, I found a small(ish) Neve console at a TV station that had spent most of its life sitting in a remote broadcast van parked in the hot tropical sun for years on end. I was able to make an offer and buy it for a reasonable price. It's coupling capacitors had degraded and leaked DC through making for lots of DC offset hitting the switches and the pots. It needed a whole re-cap. But it was amazing afterwards. I flipped it for a good profit before I even refurbished it but I had sellers remorse after that because it sounded so good when the work was done. It took at least three people to even pick it up to carry it.
I find that heat really wastes electrolytic capacitors quicky. The familiar switch mode power supply modules often have electrolytics packed tightly near to a heat sinked voltage regulator that will slowly cook it and noise comes through with the degradation. I've come to regard electrolytic capacitors as consumables.