VACUUM TUBE REPLACEMENT
Never attempt to replace vacuum tubes while the amplifier is on or the amplifier is hot.
To replace tubes remove the back panel of the amplifier. Preamplifier tubes usually have
a twist-lock shield that must be removed before the tube can be removed from the chassis.
Output tubes and rectifier tubes employ either a spring and cap arrangement
(called a
tube hat)
or a base clamp. The base clamp is loosened by un-tightening the screw on the
side of the clamp. The spring and cap version is
gently
lifted off the tube and moved out
of the way. When replacing output tubes, always check the amplifier out before replacing
the back panel. Make sure that the amplifier functions normally and that none
of
the
tubes appear to be overheating. This is usually indicated by an abnormally bright tube or
a reddish glow from the plate area. If all looks well, replace the shields, caps, or re-tighten
the clamps. Replace the rear panel and test the amplifier again.
INDICATOR LAMP REPLACEMENT
Matchless employs incandescent bayonet style lamps to illuminate the logo, stand-by
indicator, and the front panel or
dashboard.
All the lamps are of the same type for
simplicity. A lamp type #47 is recommended for all lamps, although a type #44 may be
substituted
if
a brighter look is desired.
PANEL OR DASHBOARD LAMP REPLACEMENT
There are five lamps used to illuminate the front panel of the amplifier. When one of
these lamps requires replacement, the entire chassis must be removed from the cabinet.
To do this, first remove the power cord from the amplifier. Then remove the back panel
by loosening the hold-down screws. Remove the two wires that provide power to the logo.
These are pull-off connectors. If the amplifier is a combo, disconnect the speaker plug
located neat to the fuse holder. Carefully remove the four screws on the top of the cabinet
while supporting the weight
of
the chassis with one hand. Slide the chassis out to replace
the bulbs. To re-install the chassis, simply reverse the process.
LOGO LAMP REPLACEMENT
There are four lamps used to illuminate the logo.
If
the logo appears unevenly lit one of
these lamps is probably out. The lamps are located in a reflector assembly known as a
light
box.
The light box is positioned just above the speaker(s) and is removed by
removing the securing screws and disconnecting the two wires that supply power from the
chassis. The wires are connected with quick disconnect spades. Use a long screwdriver for
easy access to the screws. If the amplifier is configured as a head, the chassis must be
removed first.
STAND-BY LAMP REPLACEMENT
To replace the standby lamp, unscrew the colored reflector lens and replace the lamp.
Make sure that the power if off before replacing this lamp otherwise arcing may damage
the socket.
