I realise this has been discussed to death but I have a question, could lack of use be a factor in the tin whisker problem?
I have a couple of Radio mobile car radios they are fitted in my Rover P5Bs one 1969 and one 1972. Both of the radios worked fine right into the early 2000s while the cars were in regular use at weekends etc. then both cars were laid up for around 10 years.
After that both radios had stopped working and the fault in both cases was shorts in the AF11x transistors.
Since zapping the transistors both sets have continued to work.
Meanwhile my aunt has a Roberts R707 which had been used almost every day from new (on a mains adaptor) until about three years ago when a kind family member bought her a DAB radio.
The Roberts was stored in a cupboard until the DAB radio packed up. (The aerial suffered fatigue and fell off!
) When tried again the Roberts wouldn't work on any waveband until I gave the module a clout.
I could make the set cut on and off by tapping the module then suddenly I couldn't. The set stayed working even when I gave the module quite a sharp tap.
The surprising thing is that it has continued to do so since.
So I just wondered could using the transistor in any way 'keep the whiskers at bay' in some way? I'm not suggesting that the transistor is "zapping" its self but is it possible that the whiskers are repelled from the transistor junction in some way when it is in use?
One it is unused they manage to penetrate the junction and cause the usual shorts?
I wondered if damp could be a factor but one of the Rovers was stored in a heated garage and in the case of my auntie's Roberts it was stored in a sideboard next to a radiator in the dining room of a modern bungalow. Damp wouldn't have affected that.
I have zapped a variety of Af1xxs in various sets and have never had any re fail however I have had some that died when Zapping..
I am tempted to do an experiment. I have two working TR82s which have AF series transistors which as far as I can see have never been disturbed. I also have a third with Transistors that have been zapped by me.
I am going to put the zapped one and one original in a cupboard and forget about them, the other original set will be kept on a shelf it the workshop and used from time to time.
I want to see if the unused sets have a problem in the future and particularly if the zapped set has a relapse..