TO RECALIBRATE AC-300B FROM 50 TO 60 HZ

Lift off the turntable platter and install 60 HZ strobe disk; set this off to the side to dry.

To remove the chassis from the case: stick a screwdriver under the chrome handle cover and snap it off. Remove the 2 screws holding the handle, and the 2 rubber feet on the opposite side. Tilt the unit on its side and slide the AC-300B out of the case.

Turn the AC-300B chassis up side down, control panel away from you, on a pillow or soft foam to protect the tone arm. Locate the speed control transport, the throwout (which disengages the motor in the off position), and the microswitch that turns off the motor when the speed control is in the off position (see drawing below).

Before actually adjusting the speed do the following two procedures. First, loosen the screw on the fiberglass plate holding the microswitch (see drawing) and pivot it to the rear of the amplifier so that it is out of the way. Second, loosen the two 1/4 inch hex nuts holding the throwout and slide it all the way toward you, out of the way.

Set the unit on its side, so you can see and reach both the top and underside of the system. Move the speed control so that the knob is pointing at 38 R.P.M. (This should be the speed at which you currently have to set the system in order to play 45 R.P.M. records). Note the position of the motor and speed control transport; this is the position you want the motor and speed control transport to be in when the knob is pointing at 45 R.P.M.

Holding the motor in place, loosen the 2 screws on the speed control transport and move the knob to 45 R.P.M. and then lightly retighten the 2 screws.

Now you can plug in the power cord, put on the platter, and check if the speed is set correctly. If more adjusting is necessary be sure to unplug the power cord before readjusting the 2 screws on the speed control transport. Do this as many times as necessary to get the speed set correctly. Only when the speed is correct should you firmly tighten these 2 screws.

BE SURE THE SPEED IS ADJUSTED CORRECTLY BEFORE PROCEEDING!

Now that the speed is set correctly unplug the unit, move the knob to the off position, and turn it over again on the pillow or foam. Loosen the screw on the fiberglass plate (see drawing) and rotate the brown microswitch until there is about 1/16 inch of clearance between the leaf and the body of the switch. Retighten the screw.

Loosen the two 1/4 inch hex nuts holding the throwout (see drawing) so that it can be repositioned. Keep the speed control in the off position, and lift the motor slightly so that you can slide the throwout back under the motor mount (metal piece) so it rests on the ledge shown in the drawing. This holds the drive wheel away from the platter in the off position. Retighten the nuts so that they are firm but not extremely tight. If you over tighten them the speed control can bind and not move freely.

Turn the unit right side up, plug in the power cord, and turn it on. Check to be sure that the turntable strobes correctly; that the motor turns off when the speed control knob is in the off position, that the speed control moves freely, and that the drive wheel disengages from the platter when the speed control knob is in the off position.

Reinstall the chassis in the case and the job is finished.