EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: Jay_Diddy_B on September 27, 2020, 10:33:03 pm
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Hi group,
There are some components that are changed on sight, in order to extend the life of equipment.
Rifa EMC capacitors
I have seen these, where for some reason, where the outer case is cracked. These tend to fail is a spectacular manner.
Schaffner EMC Filters
This may be an extension of the Rifa capacitor issue, Rifa capacitors were once regarded as the premium EMC capacitors for X and Y applications.
I am concerned about older Nichicon capacitors, or more generally electrolytic capacitors with phenolic bases. I have repaired a Keithley 2001 that was almost wrecked by leaking electrolytic capacitors.
(https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157784;image)
Link: https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg698411/#msg698411 (https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg698411/#msg698411)
HP 6035A
(https://www.eevblog.com/forum/testgear/hp6035a-500v-5a-1kw-power-supply-repair/?action=dlattach;attach=157632;image)
Link: https://www.eevblog.com/forum/testgear/hp6035a-500v-5a-1kw-power-supply-repair/msg698176/#msg698176 (https://www.eevblog.com/forum/testgear/hp6035a-500v-5a-1kw-power-supply-repair/msg698176/#msg698176)
HP 6671A
(https://www.eevblog.com/forum/testgear/hp-6671a-option-j05-j09-5v-250a-power-supply/?action=dlattach;attach=1051394;image)
Thread: https://www.eevblog.com/forum/testgear/hp-6671a-option-j05-j09-5v-250a-power-supply/msg3252034/#msg3252034 (https://www.eevblog.com/forum/testgear/hp-6671a-option-j05-j09-5v-250a-power-supply/msg3252034/#msg3252034)
The first unit in this thread is mine. Forum member Shef reported a very similar problem.
I was working on another 6671A this weekend, the capacitor had just started to leak but there was no damaged to the board after cleaning.
Preventative Maintenance
I had another HP 6671A apart to replace the Rifa and Nichicon capacitors. In this unit I pulled the Nichicon capacitors. I found that the seal was the more recent plastic seal and there was no evidence of leakage at all:
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1075792;image)
This shows the old style and new style of base. These are the same series and same value.
Does anybody know when Nichicon switched to the new style of construction?
Do you have to be concerned about these new ones leaking as much as the older ones?
My experience is limited to Nichicon, because I have found these in the equipment that I have repaired. Are other brands just as bad?
Regards,
Jay_Diddy_B
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I think the PR series is discontinued and its replacement is the PS series. If the PW series will fit, use them because they have a higher ripple current capacity. They're all categorized as switching power supply capacitors. Btw, if you see a PF series, yank 'em, they're "leakers" big-time!
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Dunno any radial caps that don't use a rubber seal now, even the most horrible cheapest rubbish.
Certainly anything of value that uses caps with phenolic bases should have them changed out ASAP as they will already be long past their 'best before' date.
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There were a few defective series (early failures) from Nichicon and United Chemicon. It happened to be around the time of the capacitor plaque early to mid 2000s.
The Rifas are more an end of life problem (as far as I can tell) and likely age or application. Similar to the older tantalum capacitors they fail spectacularly so are more noticeable. There is the Chinese stuff which is crap quality and affects whole brands, so roll the dice on that one.
Then you have physical leakage due to age which will be around the 1990s and older now, either that or they dry up.
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I think the PR series is discontinued and its replacement is the PS series. If the PW series will fit, use them because they have a higher ripple current capacity. They're all categorized as switching power supply capacitors. Btw, if you see a PF series, yank 'em, they're "leakers" big-time!
PR should be some very old general purpose series, when thing like LOW ESR capacitors did not even exist yet. Yet you suggest that LOW ESR series should be a replacement for it.
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There were a few defective series (early failures) from Nichicon and United Chemicon. It happened to be around the time of the capacitor plaque early to mid 2000s.
Issues were only with LOW ESR series, HM and HN for Nichicon in particular. These are way older and certainly not LOW ESR.
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I would do an autopsy, take one apart and see how the bung is. There's many factors at play.
I find old electrolytics with the phenolic disk use natural rubber which dries out, shrinks and cracks. Synthetic rubbers are superior EPDM or EPT (Ethylene-Propylene Terpolymer) but still can fail.
The long duration, hot wave soldering of this board could also contribute to short capacitor life. I see trapped flux as well which can attack the rubber.
I remember a period (early 80's?) where most electrolytics this size had the same construction- using phenolic. Then I believe it was replaced with the synthetic rubber bung and slot cutouts for wash, for most manufacturers.
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I think the PR series is discontinued and its replacement is the PS series. If the PW series will fit, use them because they have a higher ripple current capacity. They're all categorized as switching power supply capacitors. Btw, if you see a PF series, yank 'em, they're "leakers" big-time!
PR should be some very old general purpose series, when thing like LOW ESR capacitors did not even exist yet. Yet you suggest that LOW ESR series should be a replacement for it.
Well, maybe you should read the Nichicon catalog yourself?
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I had some of those Nichicon caps leak in TDS400 series scopes. They were around 30 years old though so I'm not sure I can really fault them for it. I've had one of those RIFA capacitors burn up once too but again it was over 30 years old so I don't really buy into the "RIFA caps are crap" thing, they just have a finite life like many other parts. The one Schaffner filter I opened up didn't have RIFA caps in it, it had more modern looking blue ones with an epoxy fill. Nichicon capacitors are top notch and they're one of my go-to brands, I'm not sure I'd expect them to last 30 years in a SMPS or other high ripple application though.
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I would do an autopsy, take one apart and see how the bung is. There's many factors at play.
I find old electrolytics with the phenolic disk use natural rubber which dries out, shrinks and cracks. Synthetic rubbers are superior EPDM or EPT (Ethylene-Propylene Terpolymer) but still can fail.
The long duration, hot wave soldering of this board could also contribute to short capacitor life. I see trapped flux as well which can attack the rubber.
I remember a period (early 80's?) where most electrolytics this size had the same construction- using phenolic. Then I believe it was replaced with the synthetic rubber bung and slot cutouts for wash, for most manufacturers.
This.
I've seen elkos with phenolic disk leak (it was popular design of the era), not related to Nichicon. Most of those that leaked were in very old equipment that had hard life..
So I would say wear and tear....
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I recently rebuilt two DACs, same model. Going by the serial numbers and component date codes, they were made about 6 months apart - late 1999 to early 2000. Both had ten 100uF 16V Nichicon lytics of the new-style construction. In the earlier unit, all ten had leaked and made quite a mess. In the later unit, they were all fine.
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Hi group,
Here are some pictures from one of the phenolic-based electrolytic capacitors. It is a Nichicon PR(M) 1000uF 50V pulled from a power supply with serial starting 3215A. I estimate this to be 1992 production.
Teardown
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076598;image)
I have torn away the aluminum case to reveal how the can to base is sealed.
[attachimg=2]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076602;image)
This is with the core removed from the aluminum case.
[attachimg=3]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076606;image)
I suspect the seal that failed is around one or both pins. The out seal is well crimped during the construction.
[attachimg=4]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076610;image)
This is the inside of the rubber seal.
[attachimg=5]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076614;image)
This is the outside of the base. I tried to separate the phenolic from the rubber and I was unable to.
Regards,
Jay_Diddy_B
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Hi groups,
The second HP 6671A that I removed the capacitors from was branded HP or the front Agilent on the serial number label.
Agilent started doing business on November 1st 1999.
The serial number starts MY 4100 so that is 2001.
This had the new style capacitors.
I am going to change the capacitor anyway since I have the unit apart.
Have members seen the new style capacitor leak?
Could it be that this problem was fixed in or around 2000?
Regards,
Jay_Diddy_B
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Snip ...
I've had one of those RIFA capacitors burn up once too but again it was over 30 years old so I don't really buy into the "RIFA caps are crap" thing, they just have a finite life like many other parts. The one Schaffner filter I opened up didn't have RIFA caps in it, it had more modern looking blue ones with an epoxy fill.
Snip ...
I am not sure that I buy the argument that the Rifa capacitors are crap either. At the time the Rifa capacitors were very widely used and regarded as the 'gold standard' in in EMC capacitors.
I think that some of the reputation comes from the position in the circuit. They are connected either from line to neutral or from line (or neutral) to ground. They are exposed to large transients and high fault currents.
Unless I see some evidence of distress, like a cracked case, I am tempted to leave them alone.
Comments?
Regards,
Jay_Diddy_B
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I am not sure that I buy the argument that the Rifa capacitors are crap either. At the time the Rifa capacitors were very widely used and regarded as the 'gold standard' in in EMC capacitors.
I think that some of the reputation comes from the position in the circuit. They are connected either from line to neutral or from line (or neutral) to ground. They are exposed to large transients and high fault currents.
They are crap and they crack even when NOS caps are just sitting in a box. No other capacitor is known to crack and explode in flames in such application. They may lose most of capacitance due to shorting and self healing but none of them explodes except Rifa.
(https://i.ebayimg.com/images/g/zycAAMXQydtTNcTJ/s-l400.jpg)
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Hi,
I found this Rifa date code table here:
https://www.yumpu.com/en/document/read/9082394/rifa-evox-y-2-emi-suppression-capacitor-1mf-west-florida- (https://www.yumpu.com/en/document/read/9082394/rifa-evox-y-2-emi-suppression-capacitor-1mf-west-florida-)
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076698;image)
And I looked at the date code on the Rifa capacitors in my HP 6671A. These capacitors are marked 'M7':
[attachimg=2]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1076702;image)
This date code July 2000 is consistent with the date from the serial number of the unit 2001.
I am not sure how to read the date code 'CS1' on the picture shown by wraper.
Regards,
Jay_Diddy_B
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Is the bung still soft and pliable? I use a non-pointy (pen end) to press and see. The leads seem to poke through a sleeve in the bung?
In your one pic the top is domed so I would think the cap overpressured and then took the piss?
I have seen big value Panasonic FC leaking at the leads, so that must be the weak spot.
The Rifa capacitors are unique having a paper dielectric and the clear epoxy. I found a box of new old stock in the lab and the sides were cracked on many of them where the epoxy is thin. I think they aren't dimensionally stable - my theory: the epoxy shrinks with age and crushes the capacitor. Other people say it's a moisture ingress problem once the housing cracks.
I'd emailed Vishay and said WTF are you doing still selling these PME271's, they should be recalled. Schaffner should recall their line filters using them too.
Can't see the demand for a paper vs plastic capacitor. Paper is still king in the utility industry for an insulator in transformers although oil-immersed.
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Hi,
There used to be, (still is?) a construction of capacitor called 'mixed dielectric'. It was a combination of oil impregnated paper and plastic. It was very robust and very reliable.
The oil filled the voids in the capacitor to eliminate corona discharge. The paper was there to keep the oil in place. The plastic film can withstand very high dc voltages.
I have ordered PHE850 and PHE840 series capacitors as replacements. They are reasonably priced at Digikey.
Jay_Diddy_B
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I winder how many of the opaque capacitors have cracked epoxy that you just can't see?
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I winder how many of the opaque capacitors have cracked epoxy that you just can't see?
It's shell that cracks.
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Is the bung still soft and pliable? I use a non-pointy (pen end) to press and see. The leads seem to poke through a sleeve in the bung?
Just be careful not to poke too close to the bungholes, lest you create a leak...
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All the RIFA or line filter gave out magic smoke when wife watch me playing the “toys” :palm:
Yes, I know that there is high possibility for those RIFA giving up when plug into 220V supply after sitting most of their life in 115V environment, but the timing can’t be so coincident. :-//
Worst case is those capacitor slowly leaking through earth which trip the GFI after some time.
Note: Not sure why HP 8950L series SA power supply use X instead of Y
[attach=1]
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RIFA caps failing wouldn't be that big of an issue if they didn't fail in the exactly opposite way a class X or Y capacitors are designed to fail.
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Note: Not sure why HP 8950L series SA power supply use X instead of Y
Are you sure it's X? This crap comes in both X and Y flavor. https://content.kemet.com/datasheets/KEM_F3016_PME271Y_Y2_250.pdf (https://content.kemet.com/datasheets/KEM_F3016_PME271Y_Y2_250.pdf)
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You are right, it was marked as 250-Y2, 300-X1. It measured 3x MOhm when I applied 250 V across it. The good one measure few hundred MOhm.
[attach=1]
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You are right, it was marked as 250-Y2, 300-X1.
That's Wima, not Rifa. They do not crack or explode AFAIK.
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You are right, it was marked as 250-Y2, 300-X1.
That's Wima, not Rifa. They do not crack or explode AFAIK.
But enough leakage tripping the GFI after few hours usage :-//
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Wimas are just as bad. I had one blow itself clean off the board a few years back. Scared the shit out of me :scared:
The point of the X/Y class capacitors is they are sacrificial so they need to be replaced regularly. The encapsulation on the RIFAs was just especially bad but they're pretty good capacitors still.
As for the electrolytics, they have a lifespan based on temperature. Leaky and bulging Nichicons in HP stuff I have seen; but only when they are run hot which does tend to happen in the E36xx units they seem to have crammed full of the damn things.
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Reading this discussion, remembered I have a really old Nichicon caps, it was given by my mentor probably >30 years ago. All this time they are stored in the box and probably with constant temperature too as its a plastic box, tucked in the corner for decades. ::)
Attached below the Nichicon caps photos, measured with LCR meter, both at 4160 uF @100Hz (funny both have reduced identically in capacitance, probably need reforming), while series resistance are still pretty low at 14 and 15 mili Ohm @ 100kHz, both don't show any sign of leakage.
Looking the discussion here, and my old caps, wondering if there is a simple circuit, not sure though, say like using cheap high power audio amplifier, and a 100kHz generator, purpose is to cook the cap like this with rated RMS current @100kHz, just to see if it leaks or heat up, or to do destructive test on a sample/new old stock cap and etc, again I am not sure what I'm thinking exacly :palm:, just pop out wildly in my mind. :P ::)
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Reading this discussion, remembered I have a really old Nichicon caps, it was given by my mentor probably >30 years ago. All this time they are stored in the box and probably with constant temperature too as its a plastic box, tucked in the corner for decades. ::)
Attached below the Nichicon caps photos, measured with LCR meter, both at 4160 uF @100Hz (funny both have reduced identically in capacitance, probably need reforming), while series resistance are still pretty low at 14 and 15 mili Ohm @ 100kHz, both don't show any sign of leakage.
Looking the discussion here, and my old caps, wondering if there is a simple circuit, not sure though, say like using cheap high power audio amplifier, and a 100kHz generator, purpose is to cook the cap like this with rated RMS current @100kHz, just to see if it leaks or heat up, or to do destructive test on a sample/new old stock cap and etc, again I am not sure what I'm thinking exacly :palm:, just pop out wildly in my mind. :P ::)
Install them on the bottom side of a PCB. ;)
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Install them on the bottom side of a PCB. ;)
Yeah, while waiting it to leak, probably to kill the time by watching the grass grow ? :-DD
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Leaking SMD capacitor in Tektronix equipment giving up fishy smell when powered :wtf:
[attach=1]
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Ugh those things were mid-plague. Have fun with that :(
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RIFA caps failing wouldn't be that big of an issue if they didn't fail in the exactly opposite way a class X or Y capacitors are designed to fail.
Exactly this. That is also the reason so many people despise tantalums as well the pyrotechnical nature of their demise.
Reading this discussion, remembered I have a really old Nichicon caps, it was given by my mentor probably >30 years ago. All this time they are stored in the box and probably with constant temperature too as its a plastic box, tucked in the corner for decades. ::)
Attached below the Nichicon caps photos, measured with LCR meter, both at 4160 uF @100Hz (funny both have reduced identically in capacitance, probably need reforming), while series resistance are still pretty low at 14 and 15 mili Ohm @ 100kHz, both don't show any sign of leakage.
I have phenolic sealed capacitors bought not long ago (3~4 years ago) that look quite similar to yours - Nichicon PW IIRC.
Old but good quality capacitors last a long time. I have many still from early ages.
However, the LCR may not be enough to mark a higher voltage capacitor like yours as good: Leakage at higher voltages may be significant and has fooled me in the past. Ideally you would get a current meter and a power supply and see how it leaks at its rated viltage.
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Reading this discussion, remembered I have a really old Nichicon caps, it was given by my mentor probably >30 years ago. All this time they are stored in the box and probably with constant temperature too as its a plastic box, tucked in the corner for decades. ::)
Attached below the Nichicon caps photos, measured with LCR meter, both at 4160 uF @100Hz (funny both have reduced identically in capacitance, probably need reforming), while series resistance are still pretty low at 14 and 15 mili Ohm @ 100kHz, both don't show any sign of leakage.
I have phenolic sealed capacitors bought not long ago (3~4 years ago) that look quite similar to yours - Nichicon PW IIRC.
Old but good quality capacitors last a long time. I have many still from early ages.
However, the LCR may not be enough to mark a higher voltage capacitor like yours as good: Leakage at higher voltages may be significant and has fooled me in the past. Ideally you would get a current meter and a power supply and see how it leaks at its rated viltage.
Yep, aware of that, I've done cap leakage measurement while ago like this -> HERE (https://www.eevblog.com/forum/beginners/is-there-any-practical-or-quick-n-dirty-method-to-measure-capacitor-leakage/msg722332/#msg722332) , at that time as I didn't have DC PSU that has high enough voltage (max. only at 37V), hence I didn't had a chance to do it at HV caps, and also old caps reforming, still have plenty of them new old stock like above.
Good thing is, just while ago I acquired -> Kikusui PMC350-0.2A (https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2866746/#msg2866746) DC PSU, which can deliver 0-350 VDC @200 mA, I guess I will be starting to play with caps leakage and reforming again, the problem I'm facing now is time. :'(
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Hi,
Today I replaced the Rifa X and Y capacitors in a 1991 vintage HP 6035A power supply:
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1090830;image)
The outer case was cracked and they are ready to fail.
All the details are here:
https://www.eevblog.com/forum/testgear/hp6035a-500v-5a-1kw-power-supply-repair/msg3281284/#msg3281284 (https://www.eevblog.com/forum/testgear/hp6035a-500v-5a-1kw-power-supply-repair/msg3281284/#msg3281284)
Regards,
Jay_Diddy_B
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Happy not house burned down day :-DD
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Happy not house burned down day :-DD
Yes, the unit was not plugged in, it has been in storage. These capacitors are directly on the mains input, before any fuses or breakers. They would be energized any time the unit is plugged in the wall.
I have a number of these 1kW power supplies and I am systematically reworking them all.
Regards,
Jay_Diddy_B
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Good deal; you dodged a bullet there.
I have a pair of 3478As to open, as well as a 3314A and a 5300B/5308A that may have these things hidden there.
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Happy not house burned down day :-DD
Yes, the unit was not plugged in, it has been in storage. These capacitors are directly on the mains input, before any fuses or breakers. They would be energized any time the unit is plugged in the wall.
I have a number of these 1kW power supplies and I am systematically reworking them all.
Regards,
Jay_Diddy_B
Have there been any actual fires attributed to these? I've had one burn up before, and a friend of mine had one fail similarly. In both cases it made a lot of stinky smoke but it didn't set anything on fire or cause any damage other than a dark smudge on the PCB. Giving off a bunch of smoke is certainly not desirable but doesn't mean something "almost caught fire" or that it is particularly dangerous.
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I got 2 Schaffner filter & 2 RIFA gave out smoke, only issue is wife watching :-DD
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Hi,
I have been systematically reworking some HP power supplies that I have in my lab. Here is a pile of Rifa, mainly Y2 capacitors that I have pulled from these supplies:
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1094298;image)
From the date codes on the capacitors and the serial numbers on the equipment they are between 25-30 years old.
About half of the capacitors were cracked, the other half have some pattern that looks like they are ready to crack.
No idea of the history of these power supplies. They were all configured for 120V operation, so the capacitors were being used at half their rated voltage.
Regards,
Jay_Diddy_B
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That's a lot of power supplies :-DD
The capacitors find themselves in all sorts of things over here in the UK. I've got rid of the ones in my vacuum cleaner and food mixer as well. In fact my mother's food mixer one exploded about 3 years ago. It still worked so she just kept using it until the smoke stopped :palm:
Here's an exploded one I found in an HP unit (attenuator switch)
(https://i.imgur.com/3Y05ptt.jpg)
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That's a lot of power supplies :-DD
Snip ..
Hi,
Just getting started ...
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1094476;image)
(Perhaps this should be in the TEA thread ;) )
Jay_Diddy_B
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If you enter the TEA thread you will never leave 8)
Definitely a candidate though :-DD
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I need to replace a couple of RIFA X2 capacitors in an expensive Eurotherm PID controller as they are cracked. These capacitors are directly across the 240V supply and thankfully have not catastrophically failed yet :phew:
I did some reading about the X and Y types and discovered that the X types are designed to fail short circuit and cause an overload of a protection fuse. This is because they are used across the supply and failing open would go undetected. Y types are used from a live rail to ground in filters and are designed to fail open circuit for reasons of safety.
Fraser
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I have a few X2 Rifa caps, but in beautiful blue packages. Here it is seen alongside a Matushita and a Teapo.
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Bonjour from France:
LYTIC: ("ELCAP") have a limited lifetime, usually 2000 service hrs, determined by the type, ambient temp and internal temp rise due to ESR and ripple current.
e.g an 85 C cap lasts 2000 hrs on average before C decreases (20%?) or ESR increases (50%?)
In decades old equipment, expect every lytic especially in PSU to be suspect.
The seal designs changed over the years, as board wash solvents and regulations evolved. Modern parts are much better.
Since 1970s we used Rubycon, Nichicon and Panasonic in production (medical, avionic, lighting, HV) with 105 C or even 135C rating.
RIFA: The RIFA parts from Ericcson in Sweden were the best quality in 1960s..1970s.
The plastic tends to craze and crack over the decades especially on temp cycling.
With 230-260V line, they are near max V rating especially when exposed to line transients in certain locations eg UK and South America.
Modern safety cap parts X, Y1, Y2 do not have that problem.
Just the ramblings of an old retired EE
Enjoy,
Jon
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I did some reading about the X and Y types and discovered that the X types are designed to fail short circuit and cause an overload of a protection fuse. This is because they are used across the supply and failing open would go undetected.
I don't think it's true. First of all, if X cap fails open, so what? They normally suppress EMI, not some catastrophic failure if they go open. And except that Rifa crap they do exactly that, simply lose all of their capacitance due to self healing mechanism. Also very often they are not fused at all, like in C14 sockets combined with filter. While failing short is a real fire hazard.
https://sh.kemet.com/Lists/FileStore/EvoxRifaRFIandSMD.pdf (https://sh.kemet.com/Lists/FileStore/EvoxRifaRFIandSMD.pdf)
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1095208;image)
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1095204;image)
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After yet another exploding Rifa suppression capacitor, I have been randomly going through my (large) collection looking for Rifa caps and replacing them with non-Rifa branded caps.
I wish someone had a definitive list of equipment that had these problematic Rifas. To get the ball rolling, here are the HP and Tektronix pieces where I discovered them so far:
HP: 1630G, 3467A, 3490A, 4140B, 4261A, 4262A, 4274A, 4280A, 5005B, 5328A, 5334B, 6236B, 8018A, 8080A, 8111A, 8165A, 8175A, 8403A, 8672A, 8683B, 8901A, 8980A.
Tektronix: 2215A, 2230, 2232, 2246, TDS520.
I have plenty more pieces to examine. Unfortunately, you can't always go by what is in a downloaded service manual. You really have to take the covers off and take a look. And sometimes they hide them! The HP 8980A's capacitor was under the heatshrink tubing surrounding the on/off switch.
If anyone would like to add to the list, please have at it.
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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.
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@Wrapper,
This was the article that I read. Maybe I misinterpreted what it said about X type capacitors and protective devices etc.
https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/ (https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/)
Fraser
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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.
That's usually the quoted lifetime at the maximum rated temperature and full rated voltage. In practice I would expect the operating life to be considerably longer, but still 30 years is hard to complain about.
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Hi,
I just replaced the Rifa capacitors in an HP 6632A power supply. Like a lot of these supplies you have to remove 80% of the screws in the unit to get access to the bottom of the circuit board. The transformer and the transformer bracket have to be removed.
Overview
[attachimg=1]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1098802;image)
The capacitors are toward the rear of the unit
Input Capacitors
[attachimg=2]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1098806;image)
Output Capacitors
[attachimg=3]
(https://www.eevblog.com/forum/repair/nichicon-electrolytic-capacitors-leaking-common-problem/?action=dlattach;attach=1098810;image)
There are Y rated capacitors on the output.
Parts needed
2x 2200pF 10mm Y caps
2x 4700pF 10mm Y caps
1x 0.22uF 20mm X cap
The unit was around 1995. All the capacitors were cracked.
Regards,
Jay_Diddy_B
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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.
That's usually the quoted lifetime at the maximum rated temperature and full rated voltage. In practice I would expect the operating life to be considerably longer, but still 30 years is hard to complain about.
Unfortunately, a) the manufacturers did not expect their products being in use for more than 30 years and therefor didn't plan for easy replacement and b) the failure is only common to certain products (like those wicked RIFA x/y caps), which might be a problem of manufacturing control or general construction, but not a "all caps are dead after 30 years".
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This is my new hobby - replacing Rifa suppression capacitors. So far I've replaced 52 of them! Almost all the X-caps were cracked as were about half of the Y-caps. Some are particularly hard to get to, for instance when they are right at the AC receptacle and inaccessible without pulling off the back panel.
I bought about 80 non-Rifa suppression capacitors of assorted values a few weeks ago. I've exhausted most values. Time for a new order. I've got a few more HP pieces that I suspect have Rifas.
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This is my new hobby - replacing Rifa suppression capacitors.
They are simply everywhere. Last I have seen were in a Sony CDP-101, what a surprise. Cracked, of course...
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I usually replaced them with Panasonic X1 / Y1 rating due to higher line voltage.
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no point in griping about capacitors that have gone bad after 30 years of life ... most capacitors have a lifespan of 2000 to 5000 hours ... you do the math.
That's usually the quoted lifetime at the maximum rated temperature and full rated voltage. In practice I would expect the operating life to be considerably longer, but still 30 years is hard to complain about.
Unfortunately, a) the manufacturers did not expect their products being in use for more than 30 years and therefor didn't plan for easy replacement and b) the failure is only common to certain products (like those wicked RIFA x/y caps), which might be a problem of manufacturing control or general construction, but not a "all caps are dead after 30 years".
I had equipment at my previous job with those Rifa caps in mains filters occasionally exploded starting from about 2015-2016. Those were made in about 2004-2005. So more like 10 years instead of 30. It needs some talent for continuing making this shit for many decades without any fix.
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This is my new hobby - replacing Rifa suppression capacitors. So far I've replaced 52 of them! Almost all the X-caps were cracked as were about half of the Y-caps. Some are particularly hard to get to, for instance when they are right at the AC receptacle and inaccessible without pulling off the back panel.
I bought about 80 non-Rifa suppression capacitors of assorted values a few weeks ago. I've exhausted most values. Time for a new order. I've got a few more HP pieces that I suspect have Rifas.
don;t forget the ones hiding in many shaffner netfilters inside hp and other equipment ...
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Those Shaffner which have voltage selection “wheel” never come cheap :palm:
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The real issue is the cracking - is the epoxy shrinking or paper absorbing moisture and ballooning out etc. They're old parts, designed before mains transients standards were established. Surely they've been updated in design?
I'd emailed Kemet and told them the PME271's are a POS and why are you still selling them? <crickets>
They're an odd part- "impregnated paper" with no self-healing unless marked "SH". Most datasheets for them say nothing about any self-healing ability. I've never measured any to see if they went low value due to aging.
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I'd emailed Kemet and told them the PME271's are a POS and why are you still selling them? <crickets>.
While there are buyers for these things, there'll be production. Keep in mind that manufacturers might not be able to change designs (qualification, perhaps?) or simply don't care for the future of thr equipment - especially if these sell cheaper that other ones more robust.
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This is my new hobby - replacing Rifa suppression capacitors. So far I've replaced 52 of them! Almost all the X-caps were cracked as were about half of the Y-caps. Some are particularly hard to get to, for instance when they are right at the AC receptacle and inaccessible without pulling off the back panel.
I bought about 80 non-Rifa suppression capacitors of assorted values a few weeks ago. I've exhausted most values. Time for a new order. I've got a few more HP pieces that I suspect have Rifas.
How are we going to compete?
1) Total number changed?
2) Total weight of Rifa X and Y caps changed?
3) Total number of uF changed?
4) Total number of screws that have to be removed to get to the most difficult little ba$tard?
:-// :popcorn:
Jay_Diddy_B
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While there are buyers for these things, there'll be production. Keep in mind that manufacturers might not be able to change designs (qualification, perhaps?) or simply don't care for the future of thr equipment - especially if these sell cheaper that other ones more robust.
In most cases there is no business reason for them to care. The capacitors we are talking about are ~30 years old. How many companies support anything once it is that old? The other day I worked on a ~12 year old $40,000 veterinary ultrasound machine, the manufacture wanted nothing to do with it and refused to provide any support, the medical equipment repair vendors turned it down too because it's "too old", so I fixed it. Once a piece of equipment is out of production and out of warranty most companies prefer if it fails sooner than later.
And these caps, at least in 120V land are not that big of a deal. I've had a grand total of ONE of them burn up, I'm sure I've got lots of them in various gear, I've never replaced one preventatively, ever. If any more of them burn up I'll replace them after the fact.
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Jay_Diddy_B writes, "How are we going to compete? Number, weight, etc... "
This is not a competition I am eager to win! With Rifa capacitors, everybody eventually loses.
I have gone through most of my pieces, but there are a few more HP pieces that I know have Rifas and a few more that I suspect also do. Why is it that those pieces are on the bottom of my stacks with 10 heavy pieces above them. My back already hurts from moving a ton of equipment around.
Photo shows the carnage so far... 57 Rifa caps preemptively replaced. Many of them look far worse in the picture than I originally found them. This is because I often found it easier to remove the cap from the component side (when getting to the foil side looked like a pain in the butt) and so were chipped or cracked or mauled by rocking them with pliers until they pulled free.
Most of the casualties were from HP and Tektronix pieces in the 1980s and early 1990s. The worst offender was the HP 8160A pulse generator with nine Rifas, followed by the HP 6621A power supply with seven Rifas and the HP 8080A word generator with six Rifas.
Whereas most of the Rifas are lurking right near the AC jack on the back panel, there were a few cases where HP used them in "non-standard" places, like after the diode bridge in the switching power supply of the HP 3764A digital transmission analyzer or on the output of the HP 6621A power supply.
I didn't do anything with the sealed line filter modules found in many pieces. I know Schaffner has a bad reputation, but replacing Rifas at about 35 cents a pop (no pun intended) is a lot nicer than $30/each for a line filter.
I will probably end up with a count of about 70 Rifa caps replaced. Maybe I will glue them all to a piece of cardboard, frame it, and hang it on the wall.
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I have gone through most of my pieces, but there are a few more HP pieces that I know have Rifas and a few more that I suspect also do. Why is it that those pieces are on the bottom of my stacks with 10 heavy pieces above them. My back already hurts from moving a ton of equipment around.
That sounds like hoarding to me. Are you actually using that equipment?
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Recent post: "That sounds like hoarding to me. Are you actually using that equipment?"
Some people call it hoarding. Some people call it collecting. Some people call it "GAS." Some people belong to "TEA." Some people enjoy fixing and restoring test equipment. Some people are building up a metrology grade lab. There is plenty of room for everyone in this hobby without being judgmental.
As far as using my equipment, I use the N pieces I have to fix the (N+1)st piece when it arrives.
N is currently equal to 409, all of them fully operational and used more frequently than you would think. If that is your definition of hoarding, so be it.
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(...)
N is currently equal to 409, all of them fully operational and used more frequently than you would think. If that is your definition of hoarding, so be it.
Well, if you are the same WN1FJU listed in the 1956 callsign book (https://archive.org/stream/Spring_1956_Radio_Amateur_Callbook/Spring_1956_Radio_Amateur_Callbook_District_1_djvu.txt), then you had plenty of time to get all this gear. :-+
(you can find a lot of stuff on the internet these days...)
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I give you an "A" for the detective work. But, alas, that's not me. I was first licensed in 1965. Still, plenty of time to amass my collection (actually, I started about 20 years ago).
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Just a Google search away... Not really much.
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Recent post: "That sounds like hoarding to me. Are you actually using that equipment?"
Some people call it hoarding. Some people call it collecting. Some people call it "GAS." Some people belong to "TEA." Some people enjoy fixing and restoring test equipment. Some people are building up a metrology grade lab. There is plenty of room for everyone in this hobby without being judgmental.
As far as using my equipment, I use the N pieces I have to fix the (N+1)st piece when it arrives.
N is currently equal to 409, all of them fully operational and used more frequently than you would think. If that is your definition of hoarding, so be it.
I mean people can do whatever they want, I certainly have hoarding tendencies myself, which is one reason I try to be aware of it and actively think of why I have something and resist the urge to buy something I already have just because it's a good deal. I know guys who have 5 or 10 of the same item collecting dust on a shelf and usually when they pass away family members are so desperate to clear out everything so they can sell the house that not knowing what is valuable and what is junk everything ends up in a landfill. It also annoys me to some degree when there are people with zero of something because someone else is sitting on a whole pile of them and buying up every one that comes along.
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It also annoys me to some degree when there are people with zero of something because someone else is sitting on a whole pile of them and buying up every one that comes along.
Hoarders getting rid of their stuff does not mean "people with zero of something" will suddenly get that something. They probably don't have "that something" because they never bothered to get it (find it/pay for it/repair it). Most of it goes to a landfill anyway and hoarders collect only a tiny part of old equipment.
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Now there is a man, who really likes smoking rifas.
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Hi, thanks for the information. Are the failed RIFA capacitors all PME 271 type ? Most of the PME271 I have, even the new old stock, NOS, have cracks. I also have RIFA PMZ2050M NOS but without cracks. Regards.
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Hi, thanks for the information. Are the failed RIFA capacitors all PME 271 type ?
Yes, those are the ones.
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Don't forget to look inside the mains power socket. Sometimes there is a filter inside it, and guess what... !
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Don't forget to look inside the mains power socket. Sometimes there is a filter inside it, and guess what... !
You mean RIFA filled pipe bomb :(
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Hi, thanks for the information. Are the failed RIFA capacitors all PME 271 type ? Most of the PME271 I have, even the new old stock, NOS, have cracks. I also have RIFA PMZ2050M NOS but without cracks. Regards.
RIFA/Kemet (whatever they call themselves in the future) PME, PMZ, PMR, PZB & PMP are all metallized paper types, throw them away unless you like the random RIFA madness failures, best place for paper based capacitors, is in history books and/or a museum.
David