Hammond C-3 Organ and Leslie 147 Speaker Repair Journal and
by Chad Hauris, Retro
Electronics and Audio Lab, Midland, TX. 4/30/06, Updated 5/28/06
This Hammond C-3 appears to date from the mid-late 50's and belongs to
a church in Odessa. The C-3 and Leslie received a complete restoration
job including replacing all capacitors in the Hammond amp chassis,
re-doing the power line wiring, and adding fuses for better overload
The Leslie amp received new 6550 and 12AU7 tubes and the paper and
electrolytic capacitors were replaced. The motors were not working
right so both of the motor mechanisms were completely dismantled,
cleaned, re-lubricated, and re-wired. A new belt was installed on the
top rotating horn.
Please click the pictures for larger views.
Front view of the C-3 during repairs.
Rear view of the Leslie before repairs.
Leslie amp before repairs. The cords going to the motors were in
bad shape and were all replaced.
Underside of the Leslie amp before repairs. The 10 K wirewound
resistor, all electrolytic and paper capacitors, and the 6550 and 12AU7
tubes were replaced.
Rear view of Leslie with back off, before repairs.
C-3 Hammond electronics chassis before repairs.
New capacitors in electronics chassis.
New capacitors in electronics chassis (view 2).
Bad solder joints at the AC power input to the electronics chassis. A
new power line cord was installed with a fuse.
More sloppy soldering at the power line wiring. This wiring was all
re-done. A 5 amp main fuse was added to the main power line and a 2 amp
fuse for the electronics chassis.
Upper Leslie horn motor. The entire assembly was dismantled, all parts
cleaned, and bearings re-lubricated.
Heat shrink tubing was used over the cloth covered wire for additional
wire insulation protection and new power cords were installed.
The way the dual motor system works is that the large motor is the fast
"Tremolo" speed motor and drives the horn belt through the pulley on
top. When the switch is set to "Chorale", the large motor shuts off and
the small motor turns on. When the small motor turns on, the shaft pops
up and contacts the rubber drive wheel at the bottom of the large
motor, thus providing a speed reduction drive through the large motor's
shaft to the pulley.
When the small motor is off and the large motor is on, the small motor
shaft retracts back out of the way.
The lower rotor motor received the same treatment.
Top view of Leslie amp after repairs, with new 6550 Electro-Harmonix
Side view of finished amp.
Leslie amp chassis with new capacitors and resistor (left side).
Right side of Leslie amp chassis with new capacitors.
Repaired motor at bottom of Leslie cabinet.
Upper Leslie motor re-installed.
Amp reinstalled in cabinet with new motor power cords.
Finished C-3 console. A new "Start" switch, power indicator lamp, and
power cord were installed.
Chad playing the C-3.
Gregory playing the C-3, returned to its church home.
Chad and Gregory with the C-3.
C-3 Keyboards at church.
Side view of Gregory and the C-3.
Leslie cabinet at the church.
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