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Page 31
Section 8: EL34 Board Filament Hook-Up
Now that we have nicely completed out EL34 hardwired boards we have to make some wiring connection to these boards.
Lay the boards out as shown in the
pictures opposite – also lay down the
two 6.3V filament supply twisted pairs
from the Mains transformer. We will be
connecting these filament wires to the
Boards. For the board closest to the
power supply you will want to trim the
filament wires to correct length to
reach the tag strip where the two
green filament wires are hooked up.
FILAMENT WIRES – A short lesson
We are using AC filament heating for the EL34’s and the
ECF80 tubes – Basically the Mains transformer
secondaries provides 6.3V AC to the tubes in order for
them to “light up” – Each channel has its own Mains
secondary to supply it.
So you will want to strip the red & blue/white wires and
insert them into the tag strip in positions 2 & 3 lining up with
the green filament wires.
DO not solder into position yet – the reason is that we are
going to add another twisted red black wire pair to the tag
strip in order to feed the filament voltage down to the
ECF80 board – read on...
Now with both sets of wires into
position go ahead and solder – make
sure that the stranded cable
completely soaks up the solder for
both wires and make a good
connection with the tag strip.
Once this step is completed you have
successfully wired in the filament wire
from the Mains transformer secondary
into the EL34 hardwired board and
also prepared the filament wire that
will be feeding the ECF80 driver board
later on.
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