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Tutorial for recapping?

Danbo69

Danbo69

Active Member
Hello all,

I'm always reading about how you should replace the capacitors on older gear. I'm relatively handy in most all areas with electronics repair being the notable exception, mostly due to never doing it. I can, however, follow directions and I'm sure there is likely a good tutorial on how to remove and replace old capacitors somewhere (likely on AK somewhere), but I can't think of good search terms that would find it for me, so I'm going to punt and ask the question here. So, does someone have a link to a tutorial on how to replace capacitors?

Thanks!
 
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Note polarity. Unsolder the old one. Solder in the new one. Assure the new one has same capacitance rating and equal or higher voltage rating.

Oh, and learn enough about capacitors to know which type to use in which circuits.

Note that by and large, "re-capping" is pertinent only to electrolytic capacitors.

If you are going down this road, you may want also consider replacing transistors as well; specifically, those known to become noisy or otherwise troublesome with age.
 
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Two more things, take plenty of before pictures, also silk screening on PCB's are sometimes wrong. When replacing electrolytic caps I use a Sharpie and make a dot on the board for the negative side of the cap. This will insure you don't get one in backwards due to the markings on the board being wrong. I've run into this especially with Marantz and Realistic gear. It can happen for transistors also.
 
Do the power supply first, then check your voltages to be sure the rest of the unit is getting the correct voltages. Think of the power supply as the heart of the unit supplying vital flow to keep the entire unit working correctly.
 
I have a working Parasound amp from the mid 80's...it sounds pretty good to me ... very low noise and plenty of juice.. When I replace the original caps in the power supply, how will the sound improve ?
 
One section at a time, PS first, so you can fix it if something goes wrong. There's way more to this than most people realize. You should read cap manufacturer's general guides first- almost any reputable manufacturer will have one on their website. Here's the Nichicon one as an example- https://www.nichicon.co.jp/english/products/pdfs/e-p_gui.pdf It's important not to stress the seal area where the wires exit at any time during the installation. You desoldering and soldering skills should be good so you don't lift traces during the process. Take pictures, keep notes. The mark of a good repairman is that he leaves no marks!

Generally, don't change film or ceramic caps. I'd never touch transistors unless they actually have a noise problem or they're one of the infamous ones like the '458. Your selection today is limited and some circuits are fussy about substitutes, phono sections in particular.
 
Unless the PS caps are so bad you have serious voltage sags at high volume or serious hum you won't hear any difference at all. All that comes out of a working PS is DC current at the correct voltages, and the only effects a bad main cap will have are 120Hz hum if not charging/discharging fast enough or volume drops on transient peaks.

Muffled bass is a good sign that the main filter caps are bad, especially if it measures better after replacement (with instruments, not your ears). Human audio memory is NOT a tape recorder, and what you heard before you did the work is long, long gone in the brain after you finished. You would have to compare by switching back and forth between before and after, which isn't really possible.

Other capacitors have a much greater effect, for instance the tone coupling caps in my Technics 120 and 130 I repaired recently -- the were all leaking, and ESR ranged from 2 to 14 ohms. Not much signal going through them clean for sure!

Main caps usually last the longest simply because they are the biggest physically, and have the smallest seal area per volume. However, if you are fond of running your amps near clipping all the time they can get hot, and that ages them much faster.

I've found that caps from the mid 80's and up are much better than the earlier ones, and heat makes a BIG difference in capacitor life. Amps that run hot, like my Kenwood KA-80, have lots of caps out of spec, amps that don't like my Yamaha R700 of similar age, do not.
 
Lavane said:
also silk screening on PCB's are sometimes wrong.
Click to expand...

This also applies to SM's-They can be wrong. If a unit operates normally before the recap-the orientation for polarity, as installed, is the final arbiter of correct polarity.

Work slowly, take pictures before and after. I use a sharpie on the solder side for the component I am swapping out. I mark before grabbing the iron, as I swear, things move around while I look away!

HPMguy said:
I've found that caps from the mid 80's and up are much better than the earlier ones
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I have found that some brands of gear made in the 90's and 00's actually fare worse. There was a change to the dielectric used-which became based on water, instead of a more expensive type used in earlier years. There were a lot of caps made and sold, where the formula for the dielectric was not correct-and failure rates were very high. Alpine (and others), bought these caps and used them in car audio gear manufactured for others. I had a bunch of them in my failing amp. No 'green legs', or obvious venting, but several were faulty.

Better home audio brands were not impacted, but there are poor quality caps installed in some gear.
 
Just what I was looking for!
I think I need to start recapping some of my stuff, Paramours and a Consonance Basie, both built back around 2000.
I still have the manuals but I got no idea where to start or what kind of caps to purchase. I remember Nichicon, Black Gates? what are some other brands to consider?
So as long as the voltage value is same or higher, but what about the capacitance value? ie 22µF can use 20µF or should it be higher also?
What kind of caps should I get to possibly increase performance?

thanks
 
What I have learned here:

Always match capacitance. It’s ok to upgrade voltage rating, but mostly not needed, unless it’s been learned that the original rating was being pushed and subject to failure, for a specific cap in that piece of gear. Higher voltage caps will be larger, so may not fit. It’s best not to crowd components, for ventilation sake.

Audio grade caps are great, and may be best in certain circuits, but I lack the understanding to know ‘which ones’ are in the signal path. Stay with reliable suppliers, and avoid suspiciously low priced ones. Caps, good caps, are still inexpensive, compared with redoing things and all the time it can take finding failed ones, and replacing them.

Many will state the enhanced performance gained with recapping with upgraded caps, and this may or not be evident to you-it’s hard for me to confirm this. Many audio improvements are apparent once new caps have been installed, because the old ones have drifted significantly in value. These replacements will bring the gear back to factory performance.

There are also some old caps that fail in rather dramatic fashion, causing damage to other components. For safety, aggravation and expense, these should be replaced. Smaller value ceramic and mylar rarely give trouble. The electrolytic types are the weakest ones.
 
ConradH said:
One section at a time, PS first, so you can fix it if something goes wrong. There's way more to this than most people realize. You should read cap manufacturer's general guides first- almost any reputable manufacturer will have one on their website. Here's the Nichicon one as an example- https://www.nichicon.co.jp/english/products/pdfs/e-p_gui.pdf It's important not to stress the seal area where the wires exit at any time during the installation. You desoldering and soldering skills should be good so you don't lift traces during the process. Take pictures, keep notes. The mark of a good repairman is that he leaves no marks!

Generally, don't change film or ceramic caps. I'd never touch transistors unless they actually have a noise problem or they're one of the infamous ones like the '458. Your selection today is limited and some circuits are fussy about substitutes, phono sections in particular.
Click to expand...

oldvinyldude said:
What I have learned here:

Always match capacitance. It’s ok to upgrade voltage rating, but mostly not needed, unless it’s been learned that the original rating was being pushed and subject to failure, for a specific cap in that piece of gear. Higher voltage caps will be larger, so may not fit. It’s best not to crowd components, for ventilation sake.

Audio grade caps are great, and may be best in certain circuits, but I lack the understanding to know ‘which ones’ are in the signal path. Stay with reliable suppliers, and avoid suspiciously low priced ones. Caps, good caps, are still inexpensive, compared with redoing things and all the time it can take finding failed ones, and replacing them.

Many will state the enhanced performance gained with recapping with upgraded caps, and this may or not be evident to you-it’s hard for me to confirm this. Many audio improvements are apparent once new caps have been installed, because the old ones have drifted significantly in value. These replacements will bring the gear back to factory performance.

There are also some old caps that fail in rather dramatic fashion, causing damage to other components. For safety, aggravation and expense, these should be replaced. Smaller value ceramic and mylar rarely give trouble. The electrolytic types are the weakest ones.
Click to expand...

There’s your tutorial. Brush up on your soldering skills and follow this guidance.
 
thanks
Any recommendations for brands, especially the ones in the signal path?
Thinking about going with DIYhifi, they have AudioNote, Nichicon and Black Gate.
I need to get the schematic and parts list to see what I want to upgrade.
 
Leestereo said:
The capacitance can be increased for decoupling/filtering duty. In the signal path, if a film capacitor replaces an electrolytic type it may be possible to decrease the value provided that the filter F3 is appropriate for the desired passband.
Click to expand...

Is there a formula for this? Or do you just lower a bit and give it a listen to determine if its to your liking?

Always like to learn .

Athanasios
 
Before doing any cap work verify the unit works correctly, if not fix the fault first, otherwise the tail chasing will begin.
Then start with the power supply, once complete ensure the output voltages on the supply match the schematic (good way to start learning to read the diagrams and quirks between manufacturers)
In my 20 or so years in the hobby have found the largest gain is in the tone section of the unit. Especially with the small value caps and removal of tantalums. Chances are most of the vintage pieces have been discussed on the forum with good insight as to replacements and why they were used.
Finally always test after each section is done, again to prevent tail chasing later.

You can accomplish this with soldering iron and braid, adding a solder sucker (good one not those cheap red rubber ones) will help. If you start to get serious about doing this will need to invest in a desolder station to save time. There are no bonus points awarded for nicking the tuner dial cord with the iron btw.

Personal caps in use are Nichicon UKL/MUSE/FG/PW and Wima films up to 4.7uf mostly due to availability and Kester solder.
 
Might also add that just getting to the caps on old gear is a learning exercise all to itself. Be sure to have ways to sort and save all the hardware as it is assured that those pesky things will hide in the furthest reaches of the bench if you take your eye off them for a minute let alone if you knock the storage container while moving stuff around. Also good lighting is a must.
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Overundr1 said:
Might also add that just getting to the caps on old gear is a learning exercise all to itself. Be sure to have ways to sort and save all the hardware as it is assured that those pesky things will hide in the furthest reaches of the bench if you take your eye off them for a minute let alone if you knock the storage container while moving stuff around. Also good lighting is a must.
index.php
Click to expand...
I bought one of those small magnetized bowls Harbor Frt. sells in the automotive tools section. Most screws are magnetic and stick to the bottom of the bowl, the fasteners that don't, are at leased still in the bowl. :D
 
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