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Old 12-28-2019, 05:09 PM   #101
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

^ The MOSFETs won't get damaged, but depending on the motherboard, other things might. Case in point, some older AMD and Intel boards from the early and mid-2000's used the CPU V_core also for the chipset (example: Intel Pentium 4 Northwood motherboards with i845 chipset). So in those cases, you'd be feeding a high voltage into some chip that shouldn't be.

With most PSUs, though, I think it should be possible to feed voltage on the output rails to reform the caps. Sometimes I back-feed 12V in my ATX PSUs to run tests on the fan controller circuit.
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Old 03-14-2020, 04:02 AM   #102
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

Hi all, I wrote here as I think it's better than open a new topic. My apologies if it isn't so...
I have to restore a very old guitar amp, trying to get it as close as possible to the original. The circuit is very simple and used only one triple electrolytic cap branded "Planet" model CTC-306 (from the '50 or so, I suppose) wich in a past repair was excluded from the circuit and replaced with three new capacitors. The amp works fine.
I tested the cap with an analog oscilloscope component tester and all thre sections show a very high ESR, even if the capacitance seem to be ok. I didn't put voltage on and think it had no voltage for more than 20yrs or possibly more...
The cap housing is made of paper, and I think that the hig ESR is due to dried out elecrolyte... If this was the case, I'm afraid the cap regeneration would fail...
Now, the big question: is there some way to regenerate the electrolyte (wich would be some sort of wet compound)?
I will try regeneration, anyway... I've seen that in case of unrecoverable cap one solution to keep it "original" is to pull out everithing and hide new caps inside, but would do as last chance...
Any other idea?
Thaks in advance.
Greetings from Italy
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Old 03-19-2020, 06:16 PM   #103
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

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Originally Posted by giampi View Post
I tested the cap with an analog oscilloscope component tester and all thre sections show a very high ESR, even if the capacitance seem to be ok. I didn't put voltage on and think it had no voltage for more than 20yrs or possibly more...
The cap housing is made of paper, and I think that the hig ESR is due to dried out elecrolyte... If this was the case, I'm afraid the cap regeneration would fail...
Now, the big question: is there some way to regenerate the electrolyte (wich would be some sort of wet compound)?
Unfortunately, no.
I'm not very knowledgeable on old gear and caps, but from what I've read, old paper caps like that have a finite shelf/useful life, as do all "wet" electrolytic caps. Given their age, they are just due for replacement. There is nothing you can do to regenerate the electrolyte. And with their high ESR, chances are nothing will happen even if you do try to "reform" them with a voltage, because more than likely, they have gone "dry" (i.e. electrolyte evaporated or disintegrated or both.)

Quote:
Originally Posted by giampi View Post
I will try regeneration, anyway... I've seen that in case of unrecoverable cap one solution to keep it "original" is to pull out everithing and hide new caps inside, but would do as last chance...
If you are trying to keep looks the exact same way, then that's probably your best bet.

I personally don't see anything offensive about old gear with new parts inside (As long as it's done sensibly, of course.) Shows that even the old stuff that's built like a tank won't last forever and needs periodic "updating" on certain components.
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Old 06-30-2020, 04:23 AM   #104
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

Hi, can you show me some simple schema for reform 2000uF/400V Sprague caps?
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Old 06-30-2020, 02:01 PM   #105
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

Read post 1 & 2, you will also need high Voltage power supply. What do you have?
https://www.qsl.net/g3oou/reform.html
https://www.nmr.mgh.harvard.edu/~reese/electrolytics/
http://www.electrojumble.org/reforming.htm
http://www.angelfire.com/electronic/...store_cap.html
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Old 06-30-2020, 03:19 PM   #106
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

ok
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Old 06-30-2020, 03:22 PM   #107
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

Once you read those information then you will understand the concept then you can apply it to your need.
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Old 07-02-2020, 08:50 PM   #108
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

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Originally Posted by AmidzaDado View Post
Hi, can you show me some simple schema for reform 2000uF/400V Sprague caps?
Probably the easiest thing to do would be to rectify mains (230/240V AC) with a full bridge rectifier, then connect each Sprague 2000 uF, 400V cap, one at a time only, to the DC output of the bridge rectifier. To limit current, use a 10-25 Watt wall-type ("regular") soldering iron and connect in series with the AC live and your bridge rectifier circuit.... i.e. similar to this:

AC live ----> 10-25 Watt soldering iron ----> full bridge rectifier ----> 2000 uF, 400V cap
AC neutral -------------------------------> full bridge rectifier ----> 2000 uF, 400V cap

A 25-Watt soldering iron (or heating element of equivalent power rating) made for 230/240V AC line will have about 2 KOhms resistance, more or less, which is perfect for charging large HV caps without overheating (it's a soldering iron made for 230V AC, after all. )

If you do build this circuit, beware of live/dangerous voltages, of course. And keep in mind your reformed caps will be charged to about 360-370V DC. As such, take good precautions to discharge them carefully and gracefully (using your 10-25W soldering iron to connect across the + and - terminals on the caps after they are reformed and removed from the reforming circuit should discharge them safely.)

Last edited by momaka; 07-02-2020 at 09:36 PM..
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Old 02-23-2021, 02:16 PM   #109
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

I have the following possible power sources available to me. Please comment.

Dell 19.5v Laptop Charger: CON: To connect to breadboard I will need to stuff the inner opening with copper wire and attach a ground wire to the outer surface. I don't want to remove the end piece (makes the thing unusable as a laptop charger). Also this is a 3-wire cable. End pice is 7.5mm, a non-standard size.

HP 32v/16v Printer power supply. PRO: Will work for 25 watt caps, Don't need to remove end piece, just insert wires directly into it. CON: output amps are 720Ma and 610 Ma. Is this a problem?

Respironics power supply. PRO: The end piece is a standard 5.5mm size. I could connect it to a standard socket.

Ryobi battery. PRO: Direct current, no ripple. !8 volt CON: Output Amps too high?

I might also consider using a Buck converter availabe for $30CAD which I could attach to the HP power supply above. I would then only need a dozen of the 1KOhm resistors/

https://www.aliexpress.com/item/3268...c003EYP9R&mp=1
Attached Images
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File Type: jpg HPendjpg.jpg (698.8 KB, 2 views)
File Type: jpg respironics12v.jpg (705.4 KB, 2 views)
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Old 02-23-2021, 09:24 PM   #110
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

Current will not be an issue, generally speaking, since you will have the series resistor(s) with the cap(s) to limit current (which is the whole point of reforming the caps, as that will make the voltage rise slowly across them.)

So both the Dell 19.5V and the HP 32/16V chargers will probably work fine. However, for 6.3V, 10V, and 16V caps, you will also need to make a voltage divider before the series resistor(s) so that the voltage is lower. Otherwise, if you use any of the above supplies on let's say 6.3V caps or 10V caps, there's a good chance you'll still damage them even with the series resistor(s) in place, because the supply voltage is too high.

Thus, either connect some kind of a circuit with which you can adjust the voltage from these power adapters *or* do similar to what I showed in post #2 with a voltage divider circuit using some resistors as a crude way to get the voltages needed.
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Old 03-23-2021, 01:58 PM   #111
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

Quote:
Originally Posted by bigbeark View Post
I have the following possible power sources available to me. Please comment.

Dell 19.5v Laptop Charger: CON: To connect to breadboard I will need to stuff the inner opening with copper wire and attach a ground wire to the outer surface. I don't want to remove the end piece (makes the thing unusable as a laptop charger). Also this is a 3-wire cable. End pice is 7.5mm, a non-standard size.

HP 32v/16v Printer power supply. PRO: Will work for 25 watt caps, Don't need to remove end piece, just insert wires directly into it. CON: output amps are 720Ma and 610 Ma. Is this a problem?

Respironics power supply. PRO: The end piece is a standard 5.5mm size. I could connect it to a standard socket.

Ryobi battery. PRO: Direct current, no ripple. !8 volt CON: Output Amps too high?

I might also consider using a Buck converter availabe for $30CAD which I could attach to the HP power supply above. I would then only need a dozen of the 1KOhm resistors/

https://www.aliexpress.com/item/3268...c003EYP9R&mp=1
While Iím not exactly an expert, I would say that of every single option you shared with us, the Dell 19.5v Laptop Charger is the one that is definitely going to work as a great power source.
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Old 03-23-2021, 02:00 PM   #112
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

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Originally Posted by momaka View Post
Current will not be an issue, generally speaking, since you will have the series resistor(s) with the cap(s) to limit current (which is the whole point of reforming the caps, as that will make the voltage rise slowly across them.)

So both the Dell 19.5V and the HP 32/16V chargers will probably work fine. However, for 6.3V, 10V, and 16V caps, you will also need to make a voltage divider before the series resistor(s) so that the voltage is lower. Otherwise, if you use any of the above supplies on let's say 6.3V caps or 10V caps, there's a good chance you'll still damage them even with the series resistor(s) in place, because the supply voltage is too high.

Thus, either connect some kind of a circuit with which you can adjust the voltage from these power adapters *or* do similar to what I showed in post #2 with a voltage divider circuit using some resistors as a crude way to get the voltages needed.
Agree. I think that the Dell 19.5v Laptop Charger will definitely get the job done in the best way possible.
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Old 11-08-2021, 04:10 PM   #113
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

I have electronic devices from 1990 and I know that these devices that have not been used for a long time cause faults and depolarization in the electrolytic capacitors, is it necessary to use these devices in the interval of 1x a month to preserve the electrolytic capacitors from failing due to disuse? are used electrolytic capacitors manufactured since 1990 and assembled in electronic circuit
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Old 11-09-2021, 02:18 PM   #114
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

It does depend on the type of equipment you have.
Some gear is high stress for the electrolytic capacitors such as a VFD motor drive or SMPS, which I would say yearly or every two years power-up is enough to prevent deterioration.
But older analog audio gear, I've had sit for 10 years and powers up fine. That doesn't stress the capacitors until high volume etc.
Vacuum tube audio, I do reform the caps if it's been many years. Sometimes HV caps are in series which does not stay shared with age and leakage currents.
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Old 11-10-2021, 06:13 AM   #115
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

I have this doubt for a long time because they are electrolytic capacitors from devices from the early 90's these electrolytic capacitors are 30 years old or a little more and various brands of electrolytic capacitors and I store them but I recently found out that it is necessary to turn them on constantly but I I don't know how long they can remain unused and without risk to electrolytic capacitors

the devices are SNES console, PS2 Slim console, 29" CRT TV and other small devices

Can any electrical electronics engineer clarify this doubt?
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Old 11-10-2021, 06:41 AM   #116
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

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I have this doubt for a long time because they are electrolytic capacitors from devices from the early 90's these electrolytic capacitors are 30 years old or a little more and various brands of electrolytic capacitors and I store them but I recently found out that it is necessary to turn them on constantly but I I don't know how long they can remain unused and without risk to electrolytic capacitors

the devices are SNES console, PS2 Slim console, 29" CRT TV and other small devices

Can any electrical electronics engineer clarify this doubt?
Youve already got another open thread asking the same question -

https://www.badcaps.net/forum/showthread.php?t=99423 .Don`t you like the advice given already.
.

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Old 11-10-2021, 07:20 PM   #117
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

not clarify
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Old 11-19-2021, 07:21 AM   #118
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

I have never heard about capacitor reconditioning, thanks for the info. Is it enough to simply apply constant DC voltage that equals a cap's rated voltage? No pulsing or amplitude modulation required?

Has anyone actually observed/measured an improvement after this procedure? Does it really work?
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Old 11-28-2021, 12:57 PM   #119
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

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Has anyone actually observed/measured an improvement after this procedure? Does it really work?
That's not how it works, this is only to prevent failure.
There will be no improvement in the capacitor.
The only difference is if it did require reforming but you don't do it: Then it will fail prematurely.
And if it is a high voltage capacitor in a DC link like a servo or frequency controller for example then it will just violently vent or explode!
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Old 11-28-2021, 04:01 PM   #120
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Default Re: How to Recondition (Reform) Electrolytic Capacitors and Why

From this whole discussion I've got the notion that this procedure is able to recondition capacitors that already degraded due to being stored without use for too long, or because they were working at voltage much lower than nominal.
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