[sdiy] 1N4148 as replacements for Germaniumdiodes.

[Colin f]

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of
> Florian Anwander
> Sent: 19 May 2016 13:09
> Subject: [sdiy] 1N4148 as replacements for Germaniumdiodes.

> a buddy of mine has a TR-606, which appearently has some shortcut diodes
in
> the matrices arount the step programming and instrument selector.
> Originally Roland uses germanium diodes 1S188FM. 1N270 or NTE110A are
> recommended as replacement. If I look at the corresponding datasheets, I
> don't see anything that would speak agains 1N4148.

If you look at the path from the drive transistor Q409 to PA0 for reading
the LT position on the instrument selector, there are three diodes in
series, including a Ge.
With a voltage drop of 3 x 0.7V, maybe they were concerned about getting too
close to the high level threshold for the input pin ?
The Ge diode gives and extra 0.4V above the threshold.

Cheers,
Colin f