Rear Panel; Power Cord Receptacle; Fuse; Ground Lift - Mesa/Boogie Formula Pre Owner's Manual

REAR PANEL:

M B
ESA OOGIE
117 V~
CIRCUIT PATENTS PENDING
1 AMP
60 HZ.
LIFT
10% 100%
GROUND
FX MIX
HANDMADE IN CALIFORNIA
A.C. POWER RECEPTACLE:
power cord supplied with your unit should be used whenever possible as we chose it for its snug fit. Because this type of RECEP-
TACLE is somewhat universal and used in many products both in and out of electronic musical instrument domain, you may use other
cords of this type when the one supplied is not available. Should this become necessary, check that the cord is seated all the way into
the RECEPTACLE to insure an uninterrupted performance. In the U.S., the proper voltage is 117 volts A.C. (110-120). Always be
M B
ESA OOGIE
117 V~
CIRCUIT PATENTS PENDING
1 AMP
60 HZ.
LIFT
100%
10%
GROUND
FX MIX
HANDMADE IN CALIFORNIA
cables to length and then need an additional cord for your studio rack or, you simply want a spare for the fabled cord bag - call us and
we will be glad to send you one for a nominal charge.
Because the Formula Pre -amp has no power tubes, it is unlikely you will ever have to replace the FUSE, thus one does

FUSE:

not appear accessable from the rear panel. However, for safety reasons the Formula does have an INTERNAL MAIN FUSE located
inside the chassis. In the unlikely event that the FUSE should ever blow, it is very easy to replace.
REPLACING THE INTERNAL FUSE: Turn the units power off. With your instrument still connected to the input - strum a few chords
with the instruments' volume turned all the way up to discharge any current left in the filter capacitors (just in case you accidentally
touch one). Unplug the A.C. power cord from its receptacle. With a small Phillips screwdriver, remove the sheet metal screws that
secure the lid to the chassis and remove the lid. Looking from the rear of the unit, you will see a small circuit board directly in front of
the power transformer with two wires coming from the Front Panel POWER switch. There under a protective plastic cover is the FUSE
in its holder. Remove the cover to expose the FUSE. You can use either your hands to remove the old FUSE or a pair of insulated
pliers to grab it - but be careful not to squeeze too hard and break the glass. Replace the FUSE with a new one of the same rating
and make sure it is a Slo-Blo type FUSE! A Fast-Blo FUSE will not last in this application. Replace the protective cover and set the
lid back on top of the unit. Plug the power cord back in and test before securing the lid with the screws.
If all is normal - turn the power back off and put in the screws, tightening them moderately tight. If the unit does not power up, flip the
POWER switch back off (remembering to discharge the capacitors again), remove the lid and FUSE cover and verify that the FUSE
is securely seated in the FUSE holder. If the replaced FUSE was secure, try another FUSE. If still no power - stop and call us or see
an authorized technician.
DO NOT attempt to fix the unit yourself! The FUSE is the only user serviceable part inside your Formula Pre-amp. Domestic
U.S.A.Models use: 1 Amp Slo-Blo. For Export Models: see your Dealer / Distributor.
This mini toggle lifts the circuit ground from the sheet metal chassis ground. Normally the ground of the circuit is

GROUND LIFT:

connected to the chassis ground such that there is one common ground. In certain rack applications, whether it be in live rack systems
with multiple pre-amps in use, or in a studio environment where the Formula is connected to a console, the common ground scenario
B
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ESA OOGIE
117 V~
CIRCUIT PATENTS PENDING
1 AMP
60 HZ.
LIFT
10% 100%
GROUND FX MIX
HANDMADE IN CALIFORNIA
RETURN - L RETURN - R
FX SEND
LD1 - LD2 EQ
RHY - LD
EXT EXT
SW SW
The Formula Pre - amp uses a removable I.E.C. type power cord to supply the A.C. power. The
sure to connect the Formula to its rated voltage to avoid damaging internal circuitry.
It is a good idea to ask when performing in an environment that you aren't sure about...(especially
older venues or outdoor events where generators are sometimes used to supply power to the stage)
what the incoming voltage rating is. Export models - see label on the unit or ask your Dealer / Distribu-
tor about the necessary voltage rating requirements. If you hard wire your live rig and cut all A.C.
actually creates a ground loop. By removing the circuit ground from chassis ground this annoying hum
can often be eliminated. There is no right way to use the Formula (grounded or lifted), but if you do not
experience any ground related noise it would be preferable to use the unit in the GROUND position(toggle
down).
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