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Michael Black[_2_] Michael Black[_2_] is offline
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Default fewer through-hole transistors available

On Fri, 17 Feb 2017, Jon Elson wrote:

Dave Platt wrote:


Thinking about it... I wonder whether those poor old transistors might
not just have been Plumb Tuckered Out?

Yes, that is another possibility I considered. If the module had been in
use for a long time, with no cooling, these are the highest power
dissipation of all the signal transistors in the unit. Always on at 23 mA.

I repaired an HP synthesizer that had about 400 Germanium transistors in it,
and about a dozen had failed. I replaced them with Silicon transistors and
then sold it on eBay before any more units went out.

I thought germanium transistors in general had a tendency to go bad over
time. They'd start leaking. Maybe manufacturing improved over time, but
then at some point, silicon took over completely, except for a handful of
uses. So you can't easily get replacements, because few germanium devices
are made now.

Michael