VAC Renaissance 30/70 - Manual (Page 6)

4
INSTALLING NEW OUTPUT TUBES
Replacement 300B output tubes should be purchased only from VAC. Output tubes are type 300B. It is important that
the tubes be checked for any tendency to mechanical or electrical shorts (see Safety Notice at the front of this manual).
It is desirable that tubes be in matched pairs for each channel, and be close to the "bogey" values for the major
parameters. Make certain that each tube fits firmly in its socket.
Refer to Figure 2 for the location and types of tubes.
ALL POWER MUST BE OFF. Remove the old tubes after they have cooled down (TUBES BECOME HOT ENOUGH
TO CAUSE SERIOUS BURNS WHEN IN OPERATION AND MAY TAKE SEVERAL MINUTES TO COOL DOWN).
Install the new tubes firmly and fully in the sockets, taking care to observe that the tube will only fit into the socket in
one orientation, as two of the pins are of larger diameter. Do not use excessive force.
If at any time the plate (the outermost metal structure) of the output tubes begins to glow bright orange or red SWITCH
OFF IMMEDIATELY. The red glow indicates that the tube is "running away", being destroyed by conducting excessive
current. Tubes may run away for several reasons:
1) The tube is not fully inserted in the socket.
2) The tube fits loosely in the socket and thus can not make correct contact. Such a tube is unusable and should
be returned to its seller.
3) The tube is defective.
Switch off immediately if any part under the gold vent grille glows orange. See Safety Notice at the front of this manual.
In the event that trouble is encountered check connections and/or try another tube. Stop if the problem persists and
consult with your dealer or VAC.
A slight violet glow in the tube is not cause for concern.
For further information, refer to Tips & Advice (A Word About Tubes in General, and A Word About Output Tubes).
REPLACEMENT OF LOW LEVEL TUBES
Refer to Figure 2 for the location and types of tubes. All power must be switched off. Allow tubes to cool down. Remove
and replace with new tubes of the appropriate types, noting the location of holes in the socket and pins of the tubes.
Replacement tubes are available from VAC and other sources.
For further information, refer to Tips & Advice: A Word About Tubes in General and Tips & Advice: A Word About
Low Level Tubes.
CARE OF CHASSIS
VAC chassis are aluminum for superior electromagnetic performance, and finished in durable textured gloss paint.
Cleaning with a damp cloth WHILE THE AMP IS SWITCHED OFF AND UNPLUGGED should suffice. Do not get
cleaning solutions onto or into the tube sockets.