User Manual

V-4B Bass Guitar Amplifier
14
Troubleshooting
In the unlikely event that your V-4B should malfunction, take a few minutes to
troubleshoot it before you call for service. You can save yourself time and money by
doing it yourself, and often the cure for the problem is something quite simple. If you
thinktheproblemmaybewornouttubes,seepage10–11forsymptomsoftubefailure.
If the problem isn’t covered above, or if the steps lead you here, then contact your
Ampeg dealer for service information. Also, you should refer the amp for servicing if it
gets dropped, has liquid spilled into it, or sustains damage to its power cord.
Block Diagram
-15dB INPUT
0dB INPUT
ULTRA
LO
GAIN
1/2 12AX7
1/2 12AX7
ULTRA
HIGH
BASS
TREBLE
1/2 12AX7
ULTRA
HIGH
BASS
TREBLE
1/2 12AX7
SELECT
MID
1/2 12AX7
MID
MASTER
1/2 12AX7
POWER AMP
INPUT
PREAMP
OUTPUT
SLAVE
OUTPUT
1/2 12AX7
1/2 12AX7
1/2 12AU7
1/2 12AU7
6L6GC
6L6GC
6L6GC 6L6GC
STANDBY
SWITCH
POWER
B+
SPEAKER
OUTPUTS
8 OHM
4 OHM
4 OHM
2 OHM
2 OHM
AMPEG BENJAMIN BLOCK DIAGRAM DMP 9.24.2012
BALANCED
LINE OUT
GROUND
LIFT