"N_Cook" schrieb:

second attempt

(Why? Your first attempt worked pretty well.)

I've now powered up and the 15 marked ones are the zeners for
setting the +/- preamp rails.

Yes, the Zener diodes were just marked with the voltage in the first
row, and the production date in the second row. The prefix SZX 21/
was implied. Kinda hard to distinguish them from the plain diodes
marked 30/32/40/42, but as the maximal voltage for the Zeners was an
SZX 21/24, there was just no collision in the numbering.

--
cheers, J"org .-.-. --... ...-- -.. . DL8DTL

http://www.sax.de/~joerg/ NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)