Hi
1SS53 are just switching diodes, nothing special. You can replace them with
any 1N914 or other fast silicon small current switch diode.
Greetings

ha scritto nel messaggio
ups.com...

2. The diodes are 1ss53 which is a Japanese switching diode. They are
hard to find. Has anyone found a direct replacement for this part that
gives equal or better performance? (I do not want to change any of the
bias resistors).

Thanks - Roger