Tube Replacement - Fender Super Bassman Instrucciones De Funcionamiento

The Super Bassman uses the following types of tubes:
Pre-Amplifier: Two 12AX7A tubes (V1, V2)
(Upper Chassis, bottom view)
Power Amplifier: One 12AX7A tube (V3), One 12AT7 tube (V4), and Six
6550C power tubes (V5, V6, V7, V8, V9 and V10)
Fuses and corresponding tube pairs
(Lower Chassis, top view)
If your amplifier is not performing as it should, refer to the
Troubleshooting section below. Generally speaking with most tube
audio amplifers the tubes are the most likely thing to fail and may
be replaced without taking your amplifier to a qualified service
technician. If any tubes need replacing, carefully read and follow
these steps. If you do not feel comfortable replacing your amplifier's
tubes, take it to an authorized Fender service center. All other service
needs should be refered to an authorized Fender service center.
There are no user serviceable parts inside the electronics chassis.
Lethal voltages exist inside your tube amplifier. Tube amplifier
components get very hot. Failure to follow all these instructions may
result in damage to your amplifier, or personal injury.
How to Replace the Tubes on Your Amplifier
1. If Fender Automatic Bias indicated a tube failure, make a note of
which tube(s) failed. NOTE: Bad tubes will remain displayed as
bad until they are replaced, even if the power is cycled on/off.
2.
Turn off the amplifier and remove the power cable from the IEC
inlet (O). You might also want to disconnect other cables (such
as the speaker, line-out, effects loop, etc) so that they are not in
the way.
3.
Caution: Tubes and transformers get very hot during operation,
and may cause burn injuries. Wait for the amplifier to cool down
before proceeding to step 4.
4.
After the amplifier has cooled down, to gain access to the
preamp tubes use a #2 Phillips screw driver to remove the 4
nickel screws holding the front grille underneath the front
panel controls. Power amp tubes can be accessed by using a
Phillips screwdriver to remove the 5 black screws holding the
rear metal grille. Remove the grille slowly and disconnect the
connector for the FAN wires.

Tube Replacement

5.
Front face of chassis
Front face of chassis
6.
7.
8.
9.
10. Reconnect the speaker cable and any other signal cables you
11. Reconnect the power cable.
12. Turn on the amplifier, but keep it in standby for at least 1
13. Press and hold the up/down adjust buttons for 2 seconds to
14. Take the amplifier out of standby and wait for the Fender
Note on Handling Tubes
It is important not to leave fingerprints, grease, or other foreign
substances on the glass surface of the tubes. This is especially
important for the power output tubes. If fingerprints or other
substances are left on the surface of the tube, they will cause the
tube to become hotter than normal in that spot, which can lead to
cracks in the glass and premature failure of the tube. Some people
recommend not touching the tubes with bare hands at all. However, it
this is usually impossible to avoid. Take the following steps to ensure
that the tubes are clean and will have the maximum possible life:
1.
2.
3.
4
You now have access to all of the tubes. Preamp tubes have
metal shields that must be twisted and pulled down to remove
them. Pull the tubes straight down to remove them. The small
driver tubes near the power tubes have no shields and may
simply be pulled straight up to remove them. The power tubes
each have a top retainer ring (and insulating washer) held down
by springs. Gently lift each retainer up pull it over the tube and
off to the side. Pull the tubes straight upward to remove them
and avoid rocking them side-to-side to prevent breakage. They
should be somewhat difficult to remove. Caution: Excessive
side-to-side motion could cause the locator pin on the bottom
of the tube to fracture in the socket, which will not be covered
by the Fender Electronic Product Warranty to remove. If you
are uncomfortable in performing this process please seek the
assistance of an Authorized Fender Electronics Service Center.
Refer to the tube chart for tube type
and location. Fuse holders are marked to
indicate the corresponding tube pairs.
Replace faulty tubes with tubes of the same
type. Refer to the note below about proper
tube handling methods. Any output tube should be replaced
with the same type (6550C) and grade.
Replace all the necessary fuses. NOTE: The type of fuses used
for the tubes can be blown without showing any visible signs
of failure. If Fender Automatic Bias indicated that one or
more tubes have failed, you should replace the fuse for the
corresponding pair(s) of tubes, even if it looks okay.
Replace the front grille and install the four nickel mounting
screws if necessary. Replace the rear metal grille and install the
five black mounting screws. Don't forget to reconnect the FAN
wires before installing the rear metal grille.
disconnected in step 2.
minute.
reset the Automatic Bias settings.
Automatic Bias display to update (10-15 seconds). If the display
still indicates that the tubes are bad, either the fuse or tubes
used as replacements were not good. Repeat steps 1-14, with
new tubes or fuses.
Wash your hands before handling the tubes.
Avoid excess handling of the tubes.
After installation of the tubes, wipe them with a clean cloth to
remove any fingerprints or foreign substances.