Examine new tube pins before inserting it in the socket. They must be straight and not inclined in
respect to the ceramic base, otherwise any bent pin could damage the socket's spring contacts,
and thus the socket and/or the tube may become unusable.
a) ut carefully the new tube ON the socket, without neither pressing nor inserting the pins. Keep
track about the pins orientation. There is a larger gap between two pins (a pin is vacant) and it
must coincide with the corresponding socket's gap. Be extremely careful about the tube screen-
grid ring, not to bend any of the socket's spring contacts. If needed, slide the tube carefully up and
down while you align these contacts. After that, count the ring contacts: there must be 16 of
them, closely fitting OUTSIDE the tube screen-grid ring. This ensures that no spring contact has
been damaged during installation.
b) Align tubes pins so that EACH one would lie precisely in the gap, and at the width center of the
socket's spring contacts. Use very small rotation movements during this alignment. Do not lift
tubes during this operation in order not to disorder screen grid ring contacts (otherwise repeat the
previous step (a).
c) Using a force of NO MORE THAN 50...60N (about 5...6kg or 12...15Lbs.), in VERTICAL DIRECTION
ONLY, push carefully the tube (holding its plate heat sink) in order to insert the tube in the socket.
If you meet a stronger resistance, do not force anymore and go back to recheck (a) and (b).
The tube must fully seat in the socket.
C A U T I O N
==========
After inserting the tube, please recheck all 16 contacts of the tube screen ring.
d) Orient the silicon rubber chimney (together with the anti-parasitic suppressor inside) so that:
- the small hole could be threaded over the temperature sensor later;
- the connections to the capacitive divider and to the ceramic capacitor could be installed to their
old places.
Now thread, by small steps in parallel, the chimney over the tube plate heat sink. Keep track not to
bend the temperature sensor during this operation. Clip the anti-parasitic-suppressor spring
contact to the tube plate and precisely orient the connection lugs to the capacitive divider nut and
to the big ceramic capacitor. Align carefully the rubber chimney, so that it firmly contact the tube
deck at the base (otherwise a part of airflow would be exhausted uselessly and the tube might
over-heat).
At last, install and tighten the screws to the capacitive divider and the ceramic capacitor, using
their original screws and lock washers (should have been saved at previous steps).
e) Insure that after the tube replacement all the wiring is restored to its former condition.
. IDLING CURRENT ADJUSTMENT.
After each tube replacement, the BIAS voltage needs to be re-adjusted in order to align the new
tube regime. There is an information screen " late Current" on the LCD, foreseen to monitor the
