Thermionic Culture THE CULTURE VULTURE Mastering Plus - Manual (Page 9)

©Thermionic Culture Ltd, 2010-2014 8
5 Servicing & Maintenance
5.1 Valves
The unit comes with a 12 month warranty covering all
parts, including valves, and it is essential that it is returned
to our factory or to the dealer from which it was purchased
for repairs to be carried out otherwise the warranty is
invalidated. There is, however, one important exception to
this rule:
Valves are quite delicate items and the most common
cause of failure, despite our choice of high quality military
grade ones.
If a fault occurs on one channel, a valve is quite likely to be
the cause, so if you feel confident and willing to do the
following, here’s the procedure:
Unplug the power and remove the top by undoing screws
which attach it. Note: 1 screw is shiny and must be
replaced in the same place. The unit can be powered up
safely without the top on provided that the screening plate
above the circuit board is not removed and reasonable
care is taken not to touch exposed connections, but don’t
change valves with the power on! Change over the 2 input
valves. These are the ones with metal screening cans
nearest the left & right sides. If you press down a little and
twist the can anti-clockwise it will come off, then gently pull
out the valve. Be careful when replacing that the pins line
up. Do not bend them! Plug back in and see if the fault has
changed sides, if not try changing the next pair in (the
“distortion” valve). Be sure not to mix up the valves as they
are different types and have different pin connections!
The valve in the centre is the output valve and is a double
triode common to both channels. This is very robust – we
have had to replace less than 11 in 11 years, so it’s
unlikely to be a problem in the 1
st
12 months. If you want
to be sure, you can replace it with the common ECC82
(12AU7) with very slightly degraded results. Spares can be
obtained from Thermionic Culture Ltd.