Transistors with whiskers?! The Infamous AF114! // Gray Bench Electronics
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- เผยแพร่เมื่อ 10 ก.พ. 2025
- In this video, we'll check out some rare germanium transistors that have a very special failure mode; tin whiskers!
NASA study: nepp.nasa.gov/...
Discussion from UK Vintage Radio forum: www.vintage-ra...
Mark Hennessy's article: www.markhenness...
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My dad had a cherished NIB Gorler FM tuner on the shelf. He passed in 1983. In the 1990's, I tried to power it up. It would not work. It had several of the AF121 transistors, I believe in both the IF strip and the tuner module. In 2007, I found the NASA research you referred to. I grudgingly tossed it in the trash, as I didn't want to deal with biasing issues of replacement silicon transistors. It didn't occur to me to try the "fix" you used. Ah well. Great video!
Tin whiskers were known about from very early days of electronics - this is why lead was incorporated into solder.
Now, of course, with lead removed from electronics tin whiskers are quickly forming across the very closely spaced connections in microelectronics: result very much more frequent failure.
Yes, it would have prevented the problem. I think gold alloying with tin may also work, but gold is very expensive.@@mal2ksc
Really informative! I had heard of 'crystal growth' inside the case,but wasn't sure what it was?Thanks' for a great video!
Super cool info! Thanks again for sharing your experience and the information you have found.
I recall the gel inside was for thermal transfer.
We used a hand crank Meggar back in the 80's
The element Germanium has a few quirks, one of them is how loosely the electrons in it's valence shell are held in place, and that's what makes Germanium behave the way it does when used as a semiconductor, the reason why Germanium is so heat sensitive is because the electrons in it's valence shell are held so loosely that they can be easily knocked-out of it just by energy in the form of heat, I've read somewhere that Germanium is a pretty "slippery" semiconductor, the electrons being held loosely in the valence shell is the main reason why Germanium transistors tend to exhibit higher leakage than Silicon transistors.
That’s wild. Love the show, keep up the awesome work. I’ve learned so much.
Thanks Joe, that was pretty helpful. I have a pile of old transistors I got from my local surplus shop that originally came from Tektronix, some definitely do not test too great. I'll have to give this a try on some of the trouble units
Great video! I too have been collecting germanium transistors for a couple years now (although my collection is mostly Soviet stuff with a few Japanese pieces here and there, haven't been able to find much American or European stuff for a reasonable price) and I never knew about this failure mode! It's definitely a useful piece of info to keep in mind, thanks for sharing!
"TO" means "transistor outline. I always wondered what the Raytheon prefix "CK" stood for. Is it an acronym?
Hammond organs grow wiskers. We make a small power supply to Zap them. Basically vaporizes them making the circuit work again till they grow and short them out again.
Have done the shield lead trick on Zenith transoceanic radios.
I have a fender amp The pots look like they are growing hair!
I had a carbon pots from Alpha Taiwan that grew whiskers in a controlled stockroom environment, It took about a decade for that to happen. Alpha was super-responsive to my concerns; they took the bad part and did a full study, including microphotographs. NASA did a study that implicated tin whiskers in sudden acceleration problems in Toyota cars. The whiskers were found on the accelerator pedal potentiometer. Oddly, the study was removed form the Internet.
just cutting the screen lead can cause instability/oscillation in some cases, especially in RF or IF circuits
I just found some germanium transistors and diodes a few days ago and I'm so F'n happy... They're not easy to find the little feckers . 👍😁🇮🇪 Crazy how we love these because they are crap... 😅
I still not sure (well apart from a guitar pedal) what I'm going to do with the ones iv found... (A load of very old radios.) 👍😁🇮🇪
In Germanium we trust
In an atom, you have a nucleus made up of a certain number of protons which determines what the element is, surrounding the protons are electrons in different shells, each shell can accomodate a certain number of electrons before it is full, one of the shells is called the Valence Shell, this shell determines the electrical characteristics of the atom, whether the element that's formed by the atom is an insulator, conductor, or a semi-conductor.
Cool
You'd want to actually connect the negative to the transistor, and positive to the shield, because the arc will melt the positive side of the arc, so connecting it like that would reduce the risk of melting the terminals
I need to find some of those test lead hooks. I use alligator clips but they're too big for a lot of applications.
Pomona electronics is the go-to!
Anyone looking for old or rare Ger. or Si Transistors, let me know. I recently purchased a large collection of electronic components from an Audio Engineer here in Silicon Valley. I won't rake you over the coals...
I am interested
I am interested in what you have .
Please contact.
Nik
Hi there. Just was looking at your text. Might be interested in your collection of germanium transistors. I love working with old solid state electronics from back in the day. I have some old transistor radios that have the older type transistors. Anyway I love to see what you have. Thanks for sharing. Take care and happy transistoring! 😊
Thank you that is one great video!
Thanks!
All i wanna known is do you all think about germanium as something out of this world???? Study Bell Laboratory original films and the introduction of the germanium transistor to Japan....out of this world knowledge when you go down that rabbit hole of wisdom.
awesome video thank you for the info
Thank you!
i'd say ANY of the metal can types of similar construction can suffer from tin whiskers, i've had AC128s (audio type) afflicted, and so far one of the later AF127 ,, and have seen the outer of the cans covered with tin whisker 'fur', it seems to happen more in 'damp' and cold storage conditions...strangely not ...yet... come across a japanese metal can of similar style to AC128 suffer this way, not yet come across any japanese or other equivalent of the AF11x types, maybe they never did any? i have a japanese made radio using all japanese types except 2 AF115s !
I've had a couple of T01 types go down, didn't think to blast them. Next time, zaparoo!
@@stevehead365 yep they short to case, make sure you connect all 3 leads together for one blasting connection or you may blow the junction instead (it happened with me , one lead came out of the croc clip,, bang went an AF116....) still not yet had any japanese metal type short..hmm,,
The whiskers can grow also on the legs of the transistor shorting out the leads or causing intermittent popping noise scrapping the leads with small knives than cleaning the legs with IPA works great
Maybe it would be possible to carefully cut the can open, clean the whiskers out and pot it in some epoxy or something, repairing the transistor.
Nifty.
I am not familiar with that Peak tester. The display says mA for leakage and you state that it is uA. I wonder why they would use mA instead of uA for that display.
Some power transistors can have leakage in the low mA. But that's the beauty of the metric system, all just powers of 10!
@@graybenchelec But my point was that micro amps should be displayed as uA not mA so you can differentiate between the two on the display.
HAs anyone tried placing the whiskered transistor in an ultrasonic cleaning bath - just a thought IF tapping with a screwdriver can break the whiskers what would vibration at kHz do?
Haha good question! Or maybe one of those polishing tumblers? 😆
Interesting idea. I tried putting the transistors in the freezer for 6 months. (tin pest). Didn't work, maybe a lower temp would have done it, who knows?
Ultrasonic might 'crack' the germanium,but it is worth a try?
wow.......
Fascinating. BTW, what is the grey putty you are using to hold the components?
Just standard poster tack from a stationary store.
Seems like those whiskers might be used to study nano-self-fabrication.
That is a good insight.
এই ট্রানজিস্টার গুলা কোথায় পাবো গুলো আমি কোথায় পাবো দয়া করে আমাকে একটু জানাবেন
Potting electronics is a good thing.
Avelbal he af 114