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 a 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 next 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 stand-by lamp, unscrew the colored reflector lens and replace the lamp.
Make sure that the power is off before replacing this lamp, otherwise arcing may damage the
socket.
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