VTL IT-85, Руководство пользователя

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IT-85 Integrated amplifier
Owner’s Manual
VTL 25
Re-tubing the VTL IT-85 requires removal of some or all of
the covers, which can expose potentially lethal voltages. Be
sure to only touch the tubes themselves, and do not allow any
part of your body or hanging jewelry to come into contact
with any part of the circuit inside the unit.
1. Diagnose the tubes: If you are not undergoing a complete re-tube for
the entire IT-85, then you must first decide how many tubes and which
tubes should be changed. Use the bias checking procedure as documented
in the previous section of this manual to find out how to measure the bias
setting of the tubes and to determine whether they are within the
acceptable range. For example if you find out from the bias
measurements that tube #1 and #3 are fluctuating frequently and they are
above or below the acceptable range this may indicate that a replacement
of these two tubes is necessary. A full power test of the IT-85 may also
need to be undertaken to ensure that all power tubes are conducting
equally.
2. Power off the IT-85: To change tubes in this IT-85 you should first
power the unit down, unplug the unit from the wall outlet and disconnect
the IT-85 from the rest of the system. Let the IT-85 stay powered off for
at least 15 minutes before working with it. Make sure the tubes are cool
before you touch them. Using a Philips #2 point screwdriver remove the
protective cage from the unit by loosening the two screws from the side of
the IT-85. Carefully remove the cover and the screws and store them in a
safe place.
3. Removing Tubes: Locate the tube you need to remove and hold onto
the upper portion of the tube towards its tip. Being careful not to bend the
tube pins or break the locating pin, gently and in small amounts rotate and
rock the tube with your fingers to loosen it from its socket until its pins are
completely disengaged from the socket. Take the tube out of the unit.