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Old Transistors.

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This subject falls loosely under the heading of wiring, so please forgive me if you are expecting to discuss kA and kW. There again some equipment may still have old transistors in it.


I have become addicted to renovating old radio cassette recorders. It has become an obsession. I saw a model advertised on fleabay that I used to own and had disposed of. I bought it with a view to renovating it and enjoying past listening pleasure with some old comedy and music cassettes.


The Philips cassette recorder is a model N2205 and just pays and records on compact cassettes. It is an early 70s model. The motor speed control will not adjust correctly and the player plays at odd speeds. Also the sound output vaires and I have to bang the machine to achieve full sound output sometimes.


The circuit boards use tin cased/ canned AC127 and AC128 transistors which I believe suffer from internal whisker growth that can cause shorts internally.


Are there any plastic cased transistors that are equivalent these days please?


Z.


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    Hello Z, these are early Germanium (rather than silicon ) transistors and I think were only made in metal cans.  Should still be possible to get them.  I suspect very few Germanium transistors (if any) were made with plastic encapsulation.  You cant just swap a silicon one as the forward voltage drop for germanium is much lower so you would also need to recalculate and change the biasing resistors.


    Best bet would be to find some new old stock that have been stored somewhere cool.

    Hope this helps.

    Peter
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  • 0
    Hello Z, these are early Germanium (rather than silicon ) transistors and I think were only made in metal cans.  Should still be possible to get them.  I suspect very few Germanium transistors (if any) were made with plastic encapsulation.  You cant just swap a silicon one as the forward voltage drop for germanium is much lower so you would also need to recalculate and change the biasing resistors.


    Best bet would be to find some new old stock that have been stored somewhere cool.

    Hope this helps.

    Peter
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