Digi-Key Sold Me 7 Year Old Capacitors - Page 1
Forum section: electronics / beginners

author: Smoky
author_rank: Frequent Contributor
timestamp: August 29, 2019, 07:57:27 pm
content: Hey Guys,On a recent order from Digi-Key, I ordered 680uf 250v electrolytic capacitors for my Tektronix TDS420's SMPS.2 of the 5 capacitors were dated 2012.I contacted Digi-Key about this and they replied that there would be no problem with them.Being new to the electronics hobby, I wasn't sure of this.I asked that they send me two "newer" capacitors and they refused.What bothers me is that one of their customer service representatives stated that Digi-Key placed an order with Nichicon last year for these same sized capacitors, but they sent me these older ones.I buy from Digi-Key to receive "new" and "fresh" products.I feel that if I wanted a 7 year old capacitor, I'd go shop on Ebay.Any opinions on this?

author: KE5FX
author_rank: Super Contributor
timestamp: August 29, 2019, 08:33:50 pm
content: What does the Nichicon data sheet say about the shelf life? If the answer is "nothing," then there's no room to complain to DigiKey. Otherwise, you may have a legit beef. It all comes down to the manufacturer's specification.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 29, 2019, 08:49:11 pm
content: I did ask them to contact Nichicon.Their response was "as long as the leads are solderable, they're still good."But I'm not sure if that response came from Nichicon or one of Digi-Key's employees.I guess it's also the fact that I receive countless Digi-Key e-mails in my inbox and Digi-Key flyers in my mailbox pushing their "new" products!Maybe they should say "new-old" products?

author: james_s
author_rank: Super Contributor
timestamp: August 29, 2019, 09:13:58 pm
content: I wouldn't worry about it. I've used decades old capacitors many times without issues. My observations suggest it is largely a myth that reasonable quality capacitors have a shelf life.

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: August 29, 2019, 09:26:26 pm
content: Also just look at all the old equipment still running, there are capacitors way older than 7 years still going strong while being used.I don't think you have anything to worry about as long as they are good quality caps.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 29, 2019, 09:29:01 pm
content: Thanks James.I just couldn't sell you something like this "as new" knowing that they were 7 years old.Maybe, and at the least, I should have been charged for what they paid for them in 2012?These capacitors cost over $5 each.When I shop at Digi-Key, I know I'm paying the "premium" price for their stuff.I guess I expected more.

author: jfiresto
author_rank: Frequent Contributor
timestamp: August 29, 2019, 09:37:30 pm
content: According to the datasheet, they are 5000h @ 105C parts. At room temperature, it should take many decades for them to lose 20% of their capacity, assuming they were competently made. Have you measured their capacitance?If that's good, I would be much more concerned about the leads. If they happily take solder, I would consider the parts to be like new.

author: Stray Electron
author_rank: Super Contributor
timestamp: August 29, 2019, 09:47:07 pm
content: Quote from: Smoky on August 29, 2019, 09:29:01 pmIMO Digikey doesn't charge a "Premium price". In fact, they charge far less than many US suppliers. But OTOH their prices ARE higher than what you would have to pay on E-bay or Aliexpress for counterfeit brand-X trash.The next time, do your home work and look and see if any other reputable supplier ofgenuineNichicon parts sells them for less than Digikey does.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 29, 2019, 10:02:59 pm
content: Jfiresto, yes I did measure the capacitance and ESR.I used the 2014 dated capacitors in the Tektronix TDS420 power supply and they measure 625uf with 0 ESR on the Peak Atlas ESR70 meter.The SMPS functions perfectly. Btw, I also changed out all of the other electrolytics and the TVS and reflowed all of the connector pins in the SMPS.I try to find and purchase the finest parts to use in my projects, I just didn't expect to get parts dated 7 years old.I heard that the original electrolytics in the Tektronix TDS 400 series scopes started failing within a year of production, and that's what concerns me about this capacitor purchase.I guess if Digi-Key is sending me old-stock parts, then these capacitors aren't moving very fast from their shelves. I guess when they said that they just replenished their stock last year of these capacitors, it made me even more irritated.I've checked every date on the capacitors that they have sent me since last Fall. I've not seen one dated older than 2016.

author: ArthurDent
author_rank: Super Contributor
timestamp: August 29, 2019, 10:21:32 pm
content: 2012 ?I've eaten MREs (meals, ready to eat) a lot older than that.I just checked these two capacitors, one made by Mallory, one by Sprague. Both read at least 10% higher capacitance than the stamped values. Despite their age they are good.

author: Stray Electron
author_rank: Super Contributor
timestamp: August 29, 2019, 10:22:38 pm
content: Just as a guess, Digikey probably had to buy 100,000 parts to get the best price and it's going to take them YEARS to sell them all.

author: edpalmer42
author_rank: Super Contributor
timestamp: August 29, 2019, 10:22:57 pm
content: Glad they worked out for you.Just to be on the safe side, I would have reformed the capacitors before using them. High voltage capacitors can have their voltage rating drop just from sitting on the shelf. A slow, current-limited charge to their rated voltage will safely restore them.I recently fixed a power supply that used six 1000 uf, 200V capacitors on the input. Since I had no idea how long it sat on the shelf, I unsoldered them and reformed each one seperately. I noticed that one took longer to charge than the others. I wonder what would have happened if I had just flipped the power switch.Ed

author: KE5FX
author_rank: Super Contributor
timestamp: August 29, 2019, 10:24:40 pm
content: Quote from: Smoky on August 29, 2019, 10:02:59 pmThat was a bit of a special case. Tektronix and many other manufacturers encountered terrible quality problems with capacitors around that time. The problems were due to specific circumstances that have long since been ironed out. (There were actually a few different waves of 'capacitor plague' that affected different components at different times, but in any case it's been a few years since we've heard widespread complaints of capacitor quality problems.)I don't think you have anything to worry about. As for inventory cycling, FIFO is the rule across pretty much all industries. The newest parts don't go out the door until the oldest ones are sold. Check the dates on the milk cartons in the back of the grocery store dairy case sometime.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 29, 2019, 10:35:51 pm
content: Yes, anytime I replace any electrolytic capacitors, the repaired project is brought up incrementally and slowly on the Variac.In the case of this SMPS, I brought the AC volts up slowly to 25 and let it sit there for three to five minutes while I check for any hot spots.I repeated that until I reached the full 120 VAC.

author: edpalmer42
author_rank: Super Contributor
timestamp: August 29, 2019, 10:49:00 pm
content: It's not a good idea to slowly bring up the input voltage on a switching supply. I've heard that sometimes they can get into a weird state where they self-destruct. Linear supplies are fine. The only thing I'd do with a switching supply is use a dim-bulb tester and an isolation transformer.Ed

author: Smoky
author_rank: Frequent Contributor
timestamp: August 29, 2019, 10:56:18 pm
content: Thanks Ed,Maybe Ive been calling my Tenma the wrong word? It does read "isolation" transformer near the dial.

author: edpalmer42
author_rank: Super Contributor
timestamp: August 29, 2019, 11:23:18 pm
content: Most isolation transformers are fixed, not variable. So I was referring to the 'isolation' feature. Yours has the additional feature of being variable. Very nice!But apparently, some switching supplies don't like having the input voltage ramped up slowly. I heard that many years ago and I don't know if it was true then or if it's true now. I've just gotten into the habit of using a dim bulb tester and a fixed isolation transformer when I work on a switching supply. That way, the supply always sees normal line voltage on startup, but it's protected in case something goes wrong.Ed

author: james_s
author_rank: Super Contributor
timestamp: August 30, 2019, 12:12:53 am
content: Quote from: Smoky on August 29, 2019, 10:35:51 pmI've heard of guys doing that when they want to try to save the 70 year old in an antique radio but anything else and it's a waste of time. I've seen zero evidence that there is any benefit of re-forming modern as in less than about 40 years old electrolytics. I have loads of 70s and 80s gear running most of the original capacitors, I only replace the ones that test bad or commonly fail and that normally happens because they are heated either externally or experience high ripple current.

author: Brumby
author_rank: Unknown
timestamp: August 30, 2019, 12:27:26 am
content: My understanding of the basic operating principle of switchmode power supplies is this:* The input voltage is rectified and used to operate an oscillator* The oscillator output is fed into the primary of a transformer, with the secondary producing the target voltage* The operating point of the oscillator is controlled to generate and regulate the target voltage (via feedback)* As such, when the input voltage is low, the oscillator will be driven harder, drawing more current so that it can deliver the required target voltage at the current required.My (simplified) interpretation of this is something along the following lines...If a SMPS requires 120VA to be able to deliver its target voltage (at the requisite current), then it will draw 1A from a supply voltage of 120V. If, however, the supply voltage is 8V, it will try to draw 15A.This level of current is likely going to be a big problem for a circuit that was designed for 1A typical.But this is just a fundamental issue. In addition to this, you will have the practical issues of the ability of theactualcircuit to operate in such a situation.On that basis, I would not be presenting any SMPS with notably low source voltages - unless it was a design meant to work with them.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 30, 2019, 12:37:36 am
content: James,I recently acquired some vintage McIntosh stereo equipment from 1973 (the transistor type not tube). I have not turned them on yet.I spoke with a technician at a local hi-fi shop and he said to bring the equipment up with a Variac slowly.He gave me an example where one of his customer's power amplifier would blow the main fuse if the amplifier sat more than a couple months without being played. It was blamed on the old power supply capacitors.Now in this SMPS, I replaced 7 large capacitors due to them physically leaking. 2200uf, 6800uf, and 680uf.Since the new capacitors have never been brought up to working voltage that I know of, are you saying it is Ok to just hit the "On" button after such a capacitor swap?I do have a Sencore LC53 Z meter, and before I install any capacitor (electrolytic or film), I test its "capacitance" for matching purposes and also the "leakage" at rated voltage. Does this classify as "reforming" the new capacitor? The leakage test is about one minute until the numbers stabilize or until the capacitor shows zero leakage (which can be less than a minute).

author: Smoky
author_rank: Frequent Contributor
timestamp: August 30, 2019, 12:54:16 am
content: Brumby,I monitored the output voltages of the SMPS as I was increasing the incoming AC voltage on the isolation transformer.The SMPS was producing correct output voltages long before I reached 120 VAC incoming.The only other lead exiting the SMPS main board that I didn't check was the output wire going to the CRT board.The display is crisp and sharp at less than 50% intensity:

author: pigrew
author_rank: Frequent Contributor
timestamp: August 30, 2019, 01:52:46 am
content: TheLGX datasheetstates:"After storing the capacitors under no load at 105°C for 1000 hours and then performing voltage treatment based on JIS C 5101-4 clause 4.1 at 20°C, they shall meet the requirements listed at right."So, apparently it's fine, but you may need to look up your JIS standard. How 105 degrees and 1000 hours translates to years at standard temperature and pressure, I don't know.There's anolder forum poston this topic, too. It links to a document from UCC describing how to use capacitors. It states that the major degradation will be solderability and leakage current increase. It suggests to power the capacitor through a 1kohm resistor at its rated voltage for 30 to 60 minutes in order to reform the Al2O3, restoring its rated leakage current.Don't worry so much about their age if they are still solderable, but reform the caps if you feel the need. My feeling is that caps from since 2007 are pretty good in terms of reliability (see capacitor plague).

author: Brumby
author_rank: Unknown
timestamp: August 30, 2019, 02:02:49 am
content: Quote from: Smoky on August 30, 2019, 12:54:16 amTHIS WAS EXACTLY MY POINT! An SMPS will do its damndest to achieve that. That is their goal in life.Theimportantquestion is: Whatcurrentwas being drawnon theinputside of the SMPS so it could produce that output voltage?With the input voltage lower than the typical operating level, the current MUST be higher - and if the voltage is significantly lower, the current will besignificantlyhigher.Edit:For example: If we have a design for an SMPS that will typically run at 1A input current and we put 5A diodes up front and then provide a voltage where the SMPS tries to pull in 15A of current, then what do you expect could happen to those diodes? Similar questions can be asked on every component on the primary side.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 30, 2019, 02:21:49 am
content: Well Brumby,All I can add is that I'm almost positive that the Tenma isolation transformer would have blown its 3 Amp fuse if the Tektronix power supply demanded more current than 3A at 120 VAC....and no loads were applied to the Tektronix SMPT while I was ramping up the AC voltage on my bench outside of the oscilloscope. None of the PCB's were connected or fed by the main ribbon cable connector, it was disconnected.Oops, maybe I shouldn't have left out this fact...and another side note toBsFeeChannelandFloobyDust, I have yet to scan the Leader LBO-302 oscilloscope schematics. I hope to return to that repair adventure very soon. Please hang in there!

author: edpalmer42
author_rank: Super Contributor
timestamp: August 30, 2019, 03:22:45 am
content: If you're using relatively low voltage capacitors, you probably don't need to reform them. It seems like they'll never degrade enough to cause a problem. With capacitors for tube devices, you *must* reform them. Line voltage is in the grey zone.The low input voltage issue that I'm talking about isn't related to the current drawn, although that could be an issue. It's simply that the input voltage isn't high enough to allow the control circuitry to wake up properly. Any startup delay doesn't work right so the output might try to enable itself when the oscillator isn't functioning properly. So, for example, the switching transistors might turn on hard and stay on. Not every circuit, not even every power-up. Maybe new designs aren't vulnerable to this. But I typically work on old supplies.For me, one occurance is one too many so I don't ramp up the input voltage on switching supplies. YMMV. I'm glad that Smoky didn't have any problems.Ed

author: Brumby
author_rank: Unknown
timestamp: August 30, 2019, 03:31:41 am
content: Quote from: Smoky on August 30, 2019, 02:21:49 amYou aren't understanding what I've said.The numbers I quoted wereMADEUP- purely to illustrate a point. I have absolutely NO idea what the numbers will actually be in your setup. Those numbersWILLBE DIFFERENT.However, while the numbers will be different,the principles still apply.Using my made up numbers to justify your setup is plain silly - and just a little bit worrying.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 30, 2019, 04:43:04 am
content: Don't you do any worrying Brumby!I just meant to say that I didn't see any unusual amperage draw on the isolation transformer (I can switch between amps and volts on the fly).The SMPS outputs are regulated, so if I'm not mistaken, a load on them isn't required during powering on.I just felt I was playing it safe by slowly bringing up the SMPS with the isolation transformer after the "new-old" capacitors were installed.I'll remember to "reform" large electrolytic capacitors before I install them in a SMPS repair next time and I will not slowly bring up the input AC voltage during the restart.The TDS420 is running very well, and I imagine it will, well into the future

author: Brumby
author_rank: Unknown
timestamp: August 30, 2019, 12:59:29 pm
content: Ah ... OK then.

author: Smoky
author_rank: Frequent Contributor
timestamp: August 31, 2019, 10:00:15 pm
content: I just received a follow-up response from Digi-Key.They refunded the cost of the five LGX capacitors from my previous order.I appreciate that, but initially, I requested of them just to send me two "newer" capacitors out of the five.Anyway, they also said that I can request capacitors not to be older beyond a certain date by using the "Order Note" comment section when placing an online order.From the responses I've received on EEVblog.com, there wasn't much to worry about concerning the 2012 capacitors, so I have no problem either.All is good and I do very much appreciate the help from the EEVblog.com community.You didn't have to go that far Digi-Key, a small credit towards my next order would have been just fine, but thank you too!

author: Brumby
author_rank: Unknown
timestamp: September 01, 2019, 01:14:42 am
content: I am not surprised by Digi-Key's response.Companies that care about their reputation will tend to address issues with a solution that only requires their attentiononceand with minimal effort. Exceeding a customer's expectations - especially on such a small matter - is the quickest and easiest way.Besides, they don't know if you are developing a project that could turn into a $10k order every month for a few years.....

author: Bud
author_rank: Super Contributor
timestamp: September 01, 2019, 02:20:18 am
content: I recently got a bunch of jelly bean logic ICs from Digikey in PDIP package, all of them of Texas Instruments brand with date codes 2018÷2019. The bizarre thing was all of them had leads blackened as if they oxidized. It was unusual for such freshly made ICs to have that. The even more weird thing was the leads were only dark on the outside of the leads, the leads sides facing each other looked normal. They came in tubes. Search for TI PDIP leads finish did not produce any recent hits. I did not speak with Digikey on that, just used an eraser to clean the leads before soldering as i wanted to go ahead with my project.

author: mcovington
author_rank: Regular Contributor
timestamp: October 02, 2019, 12:09:50 am
content: One detail: Nichicon is one of the most respected brands of capacitors, as I understand it. Maybe theirs last longer.I'm currently trying to decide whether some 15- to 30-year old capacitors in my stock should be tossed...

author: alank2
author_rank: Super Contributor
timestamp: October 02, 2019, 02:21:07 am
content: I really like Digikey's search engine, but their customer service disappoints me nearly 90% of the time I bother to contact them. They almost always want to tell you it is your fault. They love to tell you that if you didn't put it in the order notes that it is your fault. Order a part and get a date stamp that is fine Order two more and get one that has an older date stamp with errata on it. Call them and they will say "you didn't ask for the newer one, it is your fault".Mouser on the other hand has always had a good attitude with me and is quick to solve problems.

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: October 02, 2019, 10:04:02 pm
content: Quote from: Bud on September 01, 2019, 02:20:18 amThere is a situation that can occur with tin plating I have heard of but not seen myself: micro motion fretting corrosion, small wear movements of say the pin legs against the tube leave a black surface. That would explain why only the outside of the pins show it. Was any tarnish on a surface that wasn't in contact with another surface?Samtec pdf on the phenomena:http://suddendocs.samtec.com/productspecs/fretting-corrosion.pdf