6 .
M A I N T E N A N C E
The VT-4 is built with only the highest quality parts and will prove to be
extremely reliable. Vacuum tubes and electrolytic capacitors, however, have a
finite useful life and must be replaced eventually.
Top Cover Removal
Removing the top cover allows access to the vacuum tubes. 6-32 allen-head
bolts must be removed. When replacing the cover, position it so that the slotted
ventillation holes are over the tubes (towards the back ).
Vacuum Tubes
Four 6N1P tubes are used in the VT-4. V101 and V201 are the input stage
and V102 and V202 are the output stages. Tube life is difficult to predict, but it
will probably be measured in years. Catastrophic tube failure is rare with this
type of device, but a gradual increase in noise, microphonics, distortion, or a
reduction in headroom, should indicate the need for replacement. It is recom-
mended that you periodically perform a quick noise and distortion check on the
VT-4 and compare the results to previous measurements. Replacement tubes
may be obtained from us (tested and graded for low-noise and microphonics), or
other suppliers.
