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Originally posted by Helmholtz
I guess you meant on
https://nepp.nasa.gov/whisker/background/index.htm
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Thanks
I guess you meant on
https://nepp.nasa.gov/whisker/background/index.htmIt's All Over Now -
Yes, good article.Originally posted by vintagekiki View Post
In my company we once had some product failures that our scientists attributed to shorts caused by whisker growth on the PCB.
We then applied conformal coating in critical areas.
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I had a Blackstar Studio 100 come in.
Master volume on full.
Yup.
A whisker.Comment
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Originally posted by Helmholtz View Post
Hi there HH.. thanks that clears things up. I wonder if we're talking whiskers between the legs?
Anyway what Ive done is buy some bc558 pnp transistors as a start.. I couldnt get af117 replacements as very costly, even russian ones are. I got the idea from a reply in the youtube comments, under the roberts repair clip vkk kindly put up.. someone said they found these work fine.
I'll just replace & report back. Worth a shot 1st up. Thanks all.. SCComment
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To zap them tie EBC together and place a charged cap between that and the case.Comment
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Substitutes for AF117
https://www.youtube.com/watch?v=xFwDXIYgBvQ
Tin whiskers inside a AF117 transistor
https://www.radiomuseum.org/forum/af117_and_tin_whiskers.html
AF117 and Tin Whiskerhttps://www.markhennessy.co.uk/articles/vintage_transistors.htm
Transistors in Vintage Radios
https://english.electronica-pt.com/components-cross-reference?ref=AF117
Cross reference AF117
https://www.radiomuseum.org/forum/substitutes_for_af117_germanium_transistors.html
https://www.radiomuseum.org/forum/af117_transistors.html
https://www.vintage-radio.net/forum/showthread.php?t=114246
https://www.vintage-radio.net/forum/showthread.php?t=18701
AF117 replacement
https://www.vintage-radio.net/forum/showthread.php?t=97004
https://www.radios-tv.co.uk/community/radio/hacker-herald-af117-replacement/
BC557B Cheap Replacement for AF117It's All Over NowComment
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Aha ok thanks.. this is a bit beyond me unfortunately. I did tap the af117's hard, & found fairly loud interferance noise on one of them.. so I may as well try just replacing them.Originally posted by mozz View Post
What Ive done is buy bc558 transistors.. but.. how on earth I determine which bc588 leg corresponds with which af117 leg I wouldn't have clue.
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Hi there vkk.. really useful links, thank you. You are like having a really really good butler!Originally posted by vintagekiki View Post
I wonder if nos af117 transistors would just as likely suffer from tin whiskers? Or do they only grow within an electronic circuit.
If they were cheap.. Id just buy 3. But they're not you see. Not now it seems. SCComment
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Anyone know.. if I tapped the 3x af117's in circuit, & one only made noticeable noise, would it be logical to replace just this one?
I know ideally ' just replace all 3', but doing so with any transistor is a veryfiddly business, plus at £4 each I could do without replacing all 3 if poss.
Thanks, SCComment
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https://www.radiomuseum.co.uk/R200.html
Roberts R200 Overhaul
https://vintage-radio.net/forum/showthread.php?t=103804
Roberts R200 - AF117, BC557 and Noisy Output
https://www.vintage-radio.net/forum/showthread.php?t=153180
Testing an AF117 transistor
https://www.vintage-radio.com/repair-restore-information/transistor_transistor-faults.html
Transistor Faults, Testing and Replacement
https://www.vintage-radio.net/forum/showthread.php?t=156586
Transistor gainIt's All Over NowComment
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vintagekiki you are very kind to find these links for me vkk. Much appreciated.
Chaps,
I think it might make sense to try replacing these dreaded transistors one by one, with exact replacements now.. because the lead thing with 4 damn legs, is a total nightmare if I buy any other types to know which leg might go where. Absolutely impossible Id imagine for me, now I can see the full picture finally having got the chassis out.
As to the electrolytic caps.. can these just be replaced with generic 50v caps? They look alot different to general ones Im used to.
Thanks SC
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Anyone know what these old electrolytic caps polarity might be? The yellow, red jobs.
Would the obvious grey lead on one side only denote neg or positive?
thanks SC
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http://www.geofex.com/article_folders/ffselect.htm
Picking transistors for FF Clones
https://hackaday.io/project/10698-clockwork-germanium/log/35265-testing-germanium-transistors
Testing Germanium transistors
It's All Over NowComment
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Thanks for these vkk. I think O have all the www r200 transistor info now!Originally posted by vintagekiki View Posthttp://www.geofex.com/article_folders/ffselect.htm
Picking transistors for FF Clones
https://hackaday.io/project/10698-clockwork-germanium/log/35265-testing-germanium-transistors
Testing Germanium transistors
Ive pulled out a af117 & lytic cap next to it, needed to in order to get to the transitor. I see a black lower end.. obvious polarity markers then.
Will see what happens when I put in a nos mullard af117, & a generic lytic 10/50 cap. Report back.
thanks.SCComment
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Does anyone know if these tin whiskers could just as easily occur in a new old stock germanium transistor, over say a similar timespan, as one having been in a circuit?
Thanks, SCComment
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