Old Rubycon SH-series capacitor from the 1980's.

[The Electrician]

But when comparing the accuracy of the DE-5000's "Rs" mode versus "DCR" mode when checking the resistance of normal resistors (not ESR), is there a difference in accuracy?  Or will AC excitation show largely the same resistance value of a given resistor as DC excitation?

I would expect about the same accuracy for the two modes, except for very small resistances, where thermoelectric voltages can cause substantial error in the DCR mode, whereas the Rs mode is not affected by thermoelectric voltages.

[dom0]

Fluid filled electrolytic capacitors do not have eternal life, folks. They don’t last forever. I also see evidence of leaked fluid. And even when you don’t see evidence of leaked fluid, it’s very well may be that some of the fluid has dried out through the years, especially in power supplies where there’s constant heat. So yes, after 30 years, these capacitors do indeed need to be replaced.

I have seen a number of 30-50 year old electrolytics that were still fine (capacity within tolerance, reasonable ESR). Those are usually the plain-aluminium can, often made by Sprague...

You can also buy capacitors now that have life expectancy of 30k hours at 105 °C and 30 years at 50 °C.

The reason so many caps are dying so quickly is aggressive electrolytic, thin films (for capacitance density and ESR), poor sealing and most importantly high ripple currents causing lots of dissipation in them, plus external heat from other components.

[fzabkar]

I see that there is already an inductor at L205, but it's on the output side of the capacitor.
There are two links visible on the underside of the PCB. Would it be feasible to replace them with a single, axial, high frequency choke?

It seems you are suggesting I remove L203 and L205, measure their inductance, then replace them with physically smaller axial chokes of the same inductance ...

No, I'm suggesting that you remove the two wire links and replace them with a choke. If they are not links, then ignore my suggestion.

[JDW]

I'm suggesting that you remove the two wire links and replace them with a choke. If they are not links, then ignore my suggestion.

There are indeed 2 separate solid wires with no insulation (they look like staples) on the component side of the PCB in the two locations you point out.  But what inductance value (choke) are you suggesting they be replaced with?  On page 5 of the TDK PDF you linked for me, there are 10 different Lr values that are available.

So your thinking here is to replace the 2 jumper wires with chokes so as to have the chokes adjust the inrush current which you suspect is making the beep/squeal sound I am hearing, thereby allowing use of a low ESR capacitor (my Nichicon UHE1C222MHD1TO) for C214?

[fzabkar]

Yes, that's the idea. Others would be better placed to suggest appropriate parts. I used the phrase "something that looks like this" because I hadn't done any calculations or extensive searches. The +5V rail appears to have a maximum rating of 2A, so I would choose a choke with a 4A rating. The chokes have their own ESR which you would need to consider. In my case I would be using a trial and error approach, but others might have a more elegant solution. In fact I'm not even certain that this approach would work.

Edit: I'm suggesting that you replace the two links with a single choke, not one choke per link.

[JDW]

Yes, that's the idea. Others would be better placed to suggest appropriate parts. I used the phrase "something that looks like this" because I hadn't done any calculations or extensive searches. The +5V rail appears to have a maximum rating of 2A, so I would choose a choke with a 4A rating. The chokes have their own ESR which you would need to consider. In my case I would be using a trial and error approach, but others might have a more elegant solution. In fact I'm not even certain that this approach would work.
Edit: I'm suggesting that you replace the two links with a single choke, not one choke per link.

As someone who faces similar search troubles when designing electrolytics into new designs...

exmadscientist,

Since you seem to be an experienced power supply design engineer, what are your expert thoughts on the suggestion of fzabkar to use a single axial choke inductor in place of two wire jumpers (as discussed in the last couple posts)?  (My concern is that would more fundamentally change the original design than simply finding a replacement capacitor for C214 that has higher ESR & Dissipation Factor.)

[The Electrician]

If you use a moto-tool or exacto knife to cut away some of the copper foil around one of the pads where your capacitor is soldered in, there appears to be room to add a small value (.1 ohm or .05 ohm) resistor in series with the capacitor, allowing you to adjust the ESR to suit.  Of course the resistor has to be able to handle the ripple current with overheating.

[Shock]

Is there any reason you can't just use a standard cap series? Going for the high impedance long life series and moving up from 10V to 16V is lowering your ESR.

ESR is also commonly measured at 100kHz.

[JDW]

I just made the following measurements today...

DE-5000 "Rs-mode" Measurements using Calibrated TL-21 adapter.

Rubycon 10V 2200uF capacitor (SH series)
No beep/squeal at power-on (when soldered into HD20SC PSU as C214)

ESR@100Hz: 0.20Ω
ESR@120Hz: 0.19Ω
ESR@1kHz: 174mΩ
ESR@10kHz: 159mΩ
ESR@100kHz: 145mΩ

LCC 25V 2200uF capacitor (new but 16+ years old)
No beep/squeal at power-on with the same ripple & ESL spike levels as Rubycon cap.

ESR@100Hz: 0.04Ω
ESR@120Hz: 0.03Ω
ESR@1kHz: 27mΩ
ESR@10kHz: 24mΩ
ESR@100kHz: 23mΩ

Nichicon 16V 2200uF capacitor (UHE1C222MHD1TO)
Beep/Squeal at power-on & measured higher amplitude ESL spikes on scope.

ESR@100Hz: 0.02Ω
ESR@120Hz: 0.02Ω
ESR@1kHz: 10mΩ
ESR@10kHz: 9mΩ
ESR@100kHz: 7mΩ

Now let me know what you think.

Honestly, I am inclined to go with a higher ESR "new" replacement cap for C214 because it is the simplest solution overall that most people can do, and I intend to share this info with other who wish to recap the same board in like manner.  Cutting the PCB and soldering SMD resistors isn't desirable for most people.  And while the axial lead inductors may work (I still want to hear from exmadscientist about that), again, the simplest solution would be a replacement radial lead capacitor.  And I cannot recommend my LCC cap because they aren't sold anymore, so I will buy the following caps, and test them to see which I prefer to recommend to others performing recap jobs:

SEK222M010ST

228CKS010M

I was going to buy the following Panasonic cap too per the recommendation in this thread, but there's an oddball warning atop the datasheet that says "This series is no longer available for purchase in the country of Japan."  What the heck!?

EEU-EB1A222

[exmadscientist]

Yes, that's the idea. Others would be better placed to suggest appropriate parts. I used the phrase "something that looks like this" because I hadn't done any calculations or extensive searches. The +5V rail appears to have a maximum rating of 2A, so I would choose a choke with a 4A rating. The chokes have their own ESR which you would need to consider. In my case I would be using a trial and error approach, but others might have a more elegant solution. In fact I'm not even certain that this approach would work.
Edit: I'm suggesting that you replace the two links with a single choke, not one choke per link.

As someone who faces similar search troubles when designing electrolytics into new designs...

exmadscientist,

Since you seem to be an experienced power supply design engineer, what are your expert thoughts on the suggestion of fzabkar to use a single axial choke inductor in place of two wire jumpers (as discussed in the last couple posts)?  (My concern is that would more fundamentally change the original design than simply finding a replacement capacitor for C214 that has higher ESR & Dissipation Factor.)

Sorry, I'm not a power supply specialist, though I do work on them. I'm not willing to speculate on the effects of replacing wire jumpers with chokes, absent having a schematic. If it were my repair, I'd just find an appropriate electrolytic capacitor and call it done.

(And no, I most certainly have no idea why Panasonic is not willing and/or able to sell certain capacitor series in Japan any longer. This appears, judging by a PDF of theirs, to have started sometime around July and affects most of their through-hole electrolytics and none of their surface-mount parts, if I am interpreting that star correctly.)

[james_s]

I've had a lot of surface mount electrolytics leak and cause damage, but with the through-hole capacitors it has been extremely rare. In cases like this I leave the originals alone unless they test bad or show signs of leaking or bulging.

[JDW]

Here's a short video with sound:

https://youtu.be/FlD3kzvnerM

The first part of the video shows the recapped HD20SC PSU but with the stock Rubycon at C214. The second part of the video shows the waveform and beep sound with the Nichicon replacement at C214.  You can see the frequency of the beep is just over 1kHz.

And as I mentioned before, with my 16+ year old LCC cap at C214, there's no beep and the ripple and ESL spikes are almost identical to what you see with the stock Rubycon cap.

[Zero999]

A classic example of "fixed until broken completely".

Why have you changed the caps, if it was working fine? Age isn't enough argument to replace them.

I agree. It's daft to replace the capacitors, when it's not necessary and the fact that it doesn't work so well indicates it was a bad idea. The original poster should just go back to the old capacitor and leave it alone.

[james_s]

This has been a problem in the vintage arcade collecting community as well. A lot of people will take a working monitor or one with minor problems and take the shotgun approach replacing all of the electrolytics, and often the flyback and HOT with inferior Chinese replacements and then they are surprised when the monitor doesn't work properly. There are times when it makes sense to replace old parts as preventative maintenance but when doing that it's important to really understand the details and not just blindly assume that newer = better.

[Zero999]

This has been a problem in the vintage arcade collecting community as well. A lot of people will take a working monitor or one with minor problems and take the shotgun approach replacing all of the electrolytics, and often the flyback and HOT with inferior Chinese replacements and then they are surprised when the monitor doesn't work properly. There are times when it makes sense to replace old parts as preventative maintenance but when doing that it's important to really understand the details and not just blindly assume that newer = better.

I agree, except the original poster clearly isn't using fake parts, but superior ones with a lower ESR than the device was originally designed for, hence the oscillation.

The old/crappy capacitors with a high enough ESR seem to becoming harder to find, hence the original poster finding they're obsolete, so considering a solution such as a series resistor, when the capacitor does need replacing is probably a good idea, but for now: if it ain't broke, don't fix it!

[Shock]

If the new standard cap resolves the problem and the supply remains stable after testing etc I don't see a problem. It's not totally pointless as it will help someone else if they get the oscillation problem or dead caps to know what works, got to do proper RCA .

JDR take a measurement of the new caps you get, don't bother anything but 100kHz.

[JDW]

JDR take a measurement of the new caps you get, don't bother anything but 100kHz.

"JDW"? :-)

What do you mean by "don't bother anything but 100kHz"?  If you meant to say "don't bother MEASURING at any frequency other than 100kHz," could you please explain why?

[JDW]

I purchased 3 capacitors from Mouser, and measured data using my DE-5000:

Illinois Capacitor 228CKS010M 2000hr@85°C:

ESR
@100Hz = 60mΩ
@120Hz = 50mΩ
@1000Hz = 43mΩ
@10,00Hz = 39mΩ
@100,00Hz = 42mΩ

DF@120Hz = 0.090
Capacitance = 2.11mF
Q@120Hz = 11.04
θ@120Hz = -84.7°

Panasonic EEU-EB1A222 10,000hr@105°C:

ESR
@100Hz = 90mΩ
@120Hz = 90mΩ
@1000Hz = 80mΩ
@10,00Hz = 74mΩ
@100,00Hz = 65mΩ

DF@120Hz = 0.152
Capacitance = 1.95mF
Q@120Hz = 6.5
θ@120Hz = -82.0°

Cornell Dubilier SEK222M010ST 2000hr@105°C:

ESR
@100Hz = 40mΩ
@120Hz = 40mΩ
@1000Hz = 31mΩ
@10,00Hz = 29mΩ
@100,00Hz = 27mΩ

DF@120Hz = 0.070
Capacitance = 2.06mF
Q@120Hz = 14.13
θ@120Hz = -85.8°

I soldered each of the above into my power supply and tested the resulting ripple and ESL spikes on my scope.  None of these 3 caps caused the audible 1kHz beep sound at power-on, which was nice.  Surprisingly, the highest ESL spikes came from the Panasonic, and the ripple was higher than any of the other capacitors (due to its ESR).  It's rated for 10,000hrs but the ESL spikes were much higher than the other 2, so I won't be using it.  Ripple and ESL spikes were almost the same for the Illinois and Cornell caps.  I intend to use the Cornell due to its 2000hr@105°C rating versus 2000hr@85°C for the Illinois, and for its lower ESR and higher Q.

So the moral of this story is that its difficult to know which cap is best without testing.  I had thought the Panasonic would win, but due to the higher ESL spikes it produced (which still somewhat baffles me), it was put out of the running.

Thanks to all who contributed to this thread.