Are old components (30-40 years old!) any good now? - Page 1
Forum section: electronics / beginners

author: MarvinTheMartian
author_rank: Frequent Contributor
timestamp: March 19, 2017, 06:20:01 am
content: Hi all,I have some old stockpiles of components that are 30-40 years old (all through-hole of course)!Are they any good now (I know the electrolytics have probably dried out long ago) but what about the resistors, other caps, diodes, ICs, pots, etc?I'd image the resistors would be fine, and possibly the diodes & ICs but I'm not sure of the other caps or the pots (maybe these just need some Deoxit to restore them to new?).Should I be wasting my time testing/cleaning them or should I just toss them and start from scratch (now that SMD is the most common type now)?I would appreciate any advice.ThanksMarvinTheMartian

author: Ian.M
author_rank: Super Contributor
timestamp: March 19, 2017, 06:45:55 am
content: I use a fair number of 30, 40 and even 50 year old parts when breadboarding. If the specs are suitable and the part still meets them, and you aren't designing for production, why not?If they were kept clean and dry and at room-temperature, odds are that most of them are fine. Even the electrolytics may be OK - if there's no signs of leeakage, and they test as within tolerance and acceptable ESR, then reforming at full rated voltage may be all that's needed before you can use them.I wouldn't bother doing much testing in advance though - the easy option is to test stuff as you need it. Clean oxidised legs with a dry green panscourer, and check parameters of passives or basic functionality for active devices before use. For pots, put low voltage DC across the track (e.g an AA battery) and scope the wiper on X1 while moving it. You'll soon spot if its noisy, and if it doesn't clean up with a couple of end-to-end turns, you'll have to decide whether its worth trying to clean them or whether to chuck them.

author: tautech
author_rank: Super Contributor
timestamp: March 19, 2017, 06:53:04 am
content: I agree with Ian and add: hang onto them like gold, especially if you intend repairs of older equipment.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 19, 2017, 06:55:24 am
content: There are failure modes for all of these components, but in general they will work as well as the day the were born. Be aware that when you get to 50 years ago carbon composition was the common way resistors were made, and they weren't all that good when brand new. There will be similar cautions about many of the other components. But as long as you are aware of the limitations you can do good work with all of these components. Just like the engineers 40-50 years ago did.

author: MarvinTheMartian
author_rank: Frequent Contributor
timestamp: March 19, 2017, 10:52:09 am
content: Thanks for the advice everyone.I thought I'd end up chucking most of them out!I'll keep them now!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2017, 11:36:32 am
content: Most of them fine, yes. Just mind that the leads will be unusually oxidized, even if stored well. This can make breadboarding a little more annoying. Use extra flux when soldering.Tim

author: danadak
author_rank: Super Contributor
timestamp: March 19, 2017, 11:46:49 am
content: Carbon comp resistors notorious for going out of spec -http://www.ppinyot.com/links/resistors.htmElectrolytic caps electrolyte evaporating -https://www.phmsociety.org/sites/phmsociety.org/files/phm_submission/2010/phmc_10_030.pdfBlack Beauty capacitor issues -http://www.antiqueradios.com/forums/viewtopic.php?t=91359&view=previousCeramic capacitor aging -https://www.johansondielectrics.com/ceramic-capacitor-aging-made-simpleAnd then there were various vendor disasters associated with specific runs of components,for example tanatulms that had an explosion failure mechanism over time. ICs that hadmetal migration problems and package water absorption issues. Die attach issues, sodiumion contamination....so many.........Regards, Dana.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 19, 2017, 12:04:05 pm
content: Usually old parts are still good, but not mandatory. To be sure, measure each part. It happened to find on the same reel a bad resistor near perfectly good ones. Also some active components tend to grow metallic whiskers inside their case. Also, old CdNi use to short-circuit themselves.https://en.wikipedia.org/wiki/Whisker_(metallurgy)For the oxidized terminals, most of the time 2-3 light scratches along the terminals is enough, without extra flux. For ICs pins, a pencil eraser can clean the oxides just fine (after pencil-erasing the oxides, use a brush to remove the pencil eraser debris):https://hackaday.io/project/7574-the-devil-is-in-the-details/log/26489-a-pencil-eraser-trick

author: SeanB
author_rank: Super Contributor
timestamp: March 19, 2017, 12:13:06 pm
content: So, buy a $20 component tester and simply test each one when you want to use them. I do that with new components anyway, as the cheap mystery manufactured ones off Ebay can be suspect as well.Carbon composition resistors are great thermistors, varistors and noise sources, all in the same unit.

author: Seekonk
author_rank: Super Contributor
timestamp: March 19, 2017, 12:32:13 pm
content: I have big electrolytics, screw types, I am still using. Last one had a date code 8017. Tests as good as the day it was made after minimal reforming.

author: cncjerry
author_rank: Unknown
timestamp: March 19, 2017, 07:41:48 pm
content: Carbon comp resistors increase in value and over 30 yrs they could be 30% higher or more. I just rebuilt a General Radio Dial a Source CSA and all the resistors were at least 30% higher over 20yrs. Funny thing was that some were still right on the value. I remember changing everything in a Swan 750 CW modulator once before checking the resistors which had gone from 10k to over 70k each. I checked the color code on them a dozen times to make sure and finally the schematic was sent to me and yes, they were supposed to be 10k. It must be the humidity.Check the caps before putting power to them. Those I would pitch probably.I used to save all that stuff and pitch it now. People charge ridiculous prices for so-called vintage caps that aren't worth anything other than the fact that they were once used extensively in high end equipment.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 20, 2017, 12:06:43 pm
content: I have heaps of components from the 70's and 80's and they are really reliable, including some very high quality electrolytic capacitors. However, as SeanB mentioned, a component tester is key (I have a LCR meter) to properly assess the status of the components before using them on any circuit.Knowing their limitations also helps if you are building a more modern topology such as a high frequency switching DC-DC converter, for example. In this case the probability is very high the older components will not be suitable, as these converters demand different parameters that are defined by the physical construction techniques of the modern components.

author: SingedFingers
author_rank: Frequent Contributor
timestamp: March 20, 2017, 12:27:40 pm
content: Personally I don't keep old parts around even if there is nothing wrong with them. I can't face stockpiling them all. I did this for a number of years until I realised I had no idea what I had, so there was about 50Kg of boxes of crap floating around. If I wanted a resistor it turned out it was easier to just get RS or someone to deliver a pack of them next day and throw that in the "working parts" box.However it turns out people will pay crazy money for some old parts. Personally I'd filter out all the individually valuable parts (mainly Ge transistors, ICs, some capacitors i.e. polystyrene, WIMA films etc) and sell them on ebay. The remainder, sell in "component lots". Stick that cash in the bank, then buy new quality parts only as and when you need them. My entire parts stock is a small cardboard box now which is considerably easier to manage and I haven't had any difficulties doing without 50Kg of crap floating around!

author: bsudbrink
author_rank: Frequent Contributor
timestamp: March 20, 2017, 07:56:14 pm
content: I would add that some of us who are trying to repair/reproduce vintage gear will use "bad" electrolytics. The process is called "restuffing" and is used to reproduce the appearance of the original device. To that end, I'll add a "beg" here. I'm really looking for this particular cap (pictured below). I need two, but more would be better. The markings are:+-M-+2000MF 10V20-48923I should add, (clearly they are axial) 44mm long by 11mm in diameter, circa 1973.

author: james_s
author_rank: Super Contributor
timestamp: March 20, 2017, 08:10:52 pm
content: Old semiconductors are almost always fine, other parts it depends, I usually test them before using them in a project. Even electrolytic capacitors can be ok, I mean I have a few old radios from the 1970s still working on the original capacitors.Getting rid of excess accumulated parts is not hard, just get some small boxes, fill them with parts and post them on ebay, people love grab bags, especially kids, I built tons of stuff out of junkbox parts when I was younger. I loved finding boxes and jars of components at hamfests for a few bucks, sorting through it looking for treasures provided lots of entertainment.

author: danadak
author_rank: Super Contributor
timestamp: March 20, 2017, 09:08:04 pm
content: Be careful with old semis, especially the ones in plastic packages.Over time they absorb moisture and can cause issues.https://en.wikipedia.org/wiki/Moisture_sensitivity_levelRegards, Dana.

author: james_s
author_rank: Super Contributor
timestamp: March 20, 2017, 09:36:23 pm
content: I'm not doubting that it can happen, but certainly it's not common in my experience. I have lots of 30-40+ year old electronics that still works, occasionally something fails but it isn't all that often. I don't recall ever checking an old unused IC and finding it was bad.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 20, 2017, 10:03:19 pm
content: Quote from: danadak on March 20, 2017, 09:08:04 pmThat is a problem only for SMD technology, mostly because the moisture absorbed by the case of a chip can crack that component when the PCB is passed throw a soldering oven.

author: MarvinTheMartian
author_rank: Frequent Contributor
timestamp: March 21, 2017, 01:59:03 am
content: Sorry bsudbrink, I don't have anything like those caps.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 21, 2017, 02:56:23 am
content: Quote from: RoGeorge on March 20, 2017, 10:03:19 pmI can attest to that. In my experience, hygroscopic packaging is more susceptible to thermal stress when a package with a high density of pins per volume of epoxy is used. The lower pin count of older ICs or transistors are not as affected.http://ieeexplore.ieee.org/document/1202922

author: MarvinTheMartian
author_rank: Frequent Contributor
timestamp: March 21, 2017, 06:00:55 am
content: Hi All,Thanks for all the advice.I don't have that many ICs (mostly 555s) so if they don't test out, it's probably simpler just to restock those.Ditto for the non-electrolytic caps.Reforming the electrolytics sounds way too much effort for the number of them I have - again I'll just restock.I've got tons of resistors so I might keep them and de-oxidise the leads and test them prior to use in bread boarding.Anyone have a recommendation for a component tester or should I just pick one off Ebay (I did see that one of the TheSignalPath's giveaway items recently that Shahria was impressed with - "TAOBAO FISH 8840" but I couldn't find one online)?Thanks again everyone.MarvinTheMartian

author: Ian.M
author_rank: Super Contributor
timestamp: March 21, 2017, 06:55:42 am
content: I'd bet the 555s will be fine. Set up a basic astable multivibrator on a breadboard with a pair of LEDs (+ series resistors) from the output to the VCC and Gnd rails, get it working then swap them in one at a time. Discard any with really rusty pins. Light oxidisation can easily be cleaned off the pens with a fiberglass pencil brush.Reforming electrolytics is pretty easy, but if they are small cheap & nasty may not be worth it. Post a photo and we'll advise from there.The non-electrolytic caps are likely to be OK, Apart from some ancient waxed paper ones they rarely go bad in storage. Most older ones have longer lead lengths and are more convenient for breadboarding than modern replacements. Again post a photo . . .

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: March 21, 2017, 12:25:49 pm
content: I blieve some components will even get better over time in certain respects (certain resistor types will drift less and less as time progresses. Same with certain reference circuits (I believe here because the diffusion that slowly takes place slows down as it progresses). I don't know how much this happens at room temperature tho. I seem to remember it being a big deal in stuff like voltage standards, where an old but recenetly calibrated standard can outperform a newer one because it's just older and drifts less.