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LiftMaster 3900 Support Question

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Question posted by ccardin on November 25th, 2012

Opens But Slips Closed

opens but slowly falls closed

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Answer #1: Posted by GarageDoorMafiadotcom on December 1st, 2012 1:18 AM

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GarageDoorMafiadotcom

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Check to make sure that you don't have a broken spring on the door. Look @ the springs up above the door, if you see a 2" gap in between the coils you need new springs.

Close the door and pull the emergency release cord and you will feel and hear a click. The cord is on the bottom of the box. Then lift open the door by hand to about half open, where it should stay by it self only supported by its springs, if dropping rapily you need the springs adjusted or replaced by a trained person.

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Related LiftMaster 3900 Manual Pages

3900PLD Manual - Page 1

...'s Manual See Page 13 for ■ Please read this manual and the enclosed safety materials carefully! ■ Fasten the manual near the door after installation. ■ The door WILL NOT CLOSE unless The Protector System® and cable tension monitor are connected and properly aligned. ■ Periodic checks of the operator are required...

3900PLD Manual - Page 2

...safety instructions 7 Position the operator 7 Attach the emergency release rope and handle 8 Install power door lock (Not Provided 8 Attach the cable tension monitor (Required 9 Install the single button control...monitor 20 To open door manually 20 Operation 21-25 Operation safety instructions 21 Using your door operator 21 Care of your garage door and/or the garage door operator if you...

3900PLD Manual - Page 3

...floor mounting of the safety reversing sensors will be used in the carton. NOTE: Inspect the torsion bar while the door is no more than 14' (4.2 m) high. • 4"-6" (10 cm - 15 cm) drums, not ...model 475LM EverChargeTM Standby Power Unit is strongly recommended if there is no access door to the garage, as this operator cannot be required. Additional materials may not work properly. ...

3900PLD Manual - Page 6

... 2 Attach Mounting Bracket to the Operator • Loosely attach slotted side of mounting bracket to collar slip. Do not tighten set screws until instructed. Illustrations shown are facing up for left or the right .... Figure 2 RIGHT HARDWARE SHOWN ACTUAL SIZE Screw #10-32 WRONG Socket Wrench 6 The door may not reverse correctly or limits may be lost due to the same side of collar ...

3900PLD Manual - Page 8

... springs or unbalanced door could result in an open door falling rapidly and/or unexpectedly. • NEVER use emergency release handle to disengage door ONLY when door is fully closed. 1. Fasten power door lock to the ... bell wire up from the end of the rope to prevent slipping. • Thread the other end of the garage door track with a match or lighter to motor unit. Emergency Release...

3900PLD Manual - Page 14

... beam while the door is not connected to the door operator BEFORE installing the safety reversing sensor. Be sure power is closing, the door will stop and reverse to full open position, and the...avoid drilling extra holes in the path of sectional doors without additional hardware. This required safety device MUST NOT be installed inside the garage 14 Safety Reversing Sensor 6" (15 cm) max...

3900PLD Manual - Page 16

...eye is off, dim, or flickering (and the invisible light beam path is not obstructed), alignment is closing, the door will glow regardless of alignment or obstruction. Figure 5 Wing Nut 1/4"-20 Carriage Bolt 1/4"-20x1/2" Lens ... wing nut. If the receiving eye indicator light is already open wire to grey (Figure 6). If the sending eye indicator light does not glow steadily after ...

3900PLD Manual - Page 17

.... Push the door control or programmed remote control. Push and hold the black button until the door is closed position. 7. Repair door first. • Incorrect adjustment of safety reversal system. • After ANY adjustments are made, the safety reversal system MUST be sure fully open . Push and hold until the LED starts flashing slowly, then release...

3900PLD Manual - Page 18

... or programmed remote control. Push the door control or programmed remote control again. The door will close the door fully, inspect the door to enter unit into the Force Adjustment Mode. If the garage door opener cannot open and close (DOWN). 3. If the door is not sticking or binding. Figure 1 LED Purple Button Black Button Figure 2 Push Purple button twice to...

3900PLD Manual - Page 19

... made, the safety reversal system MUST be SERIOUSLY INJURED or KILLED by a closing door. If the operator closes the door when the safety reversing sensor is misaligned or obstructed). ADJUSTMENT STEP 3 Test the Safety Reversal System TEST • With the door fully open the door. • Place the operator carton in the path of the operator. Upon...

3900PLD Manual - Page 20

.... • Reconnect the door to the closed if possible. Test the emergency release: • Make sure the door is clear of persons and obstructions. To reconnect the door to disengage door ONLY when door is heard from the unit and lift the door manually. Weak or broken springs or unbalanced door could result in an open door falling rapidly and/or...

3900PLD Manual - Page 21

...ALWAYS keep door in the opening , the door will close . After ANY adjustments are made by a trained door systems technician. 12. An improperly balanced door may not reverse when required and could result in an open . 2. ALWAYS disconnect electric power to operate or play with door control push buttons or remote controls. 3. If closed . If closing , the door will open door falling rapidly...

3900PLD Manual - Page 22

... hinges. Do not grease the door tracks. 22 Make any necessary adjustments (see Adjustment Steps 1 and 2). • Repeat the safety reverse test. Adjust limits and/or force if necessary (see Adjustment Step 3). If it is unbalanced or binding, call a trained door systems technician. • Check to be sure door opens & closes fully. The operator does...

3900PLD Manual - Page 23

.... Have it out of ice or snow under the door? The door doesn't open completely: • Is something obstructing the door? Open and close : • Check cable tension monitor (see below. The door may be broken. Operator operates from the remote only. The door opens and closes by its springs. The door reverses for no apparent reason: • Check cable tension...

3900PLD Manual - Page 24

...operation: • Some minor movement is mounted at a right angle to disconnect the door. If not, move the position of the mounting bracket. 24 If it rotates....to power failure: • Use the emergency release handle to the jackshaft. Having a Problem? (Continued) 12. The door can be able to operate up and down as it is excessive the collar will wear prematurely. • Check to...

3900PLD Manual - Page 25

...Door reverses while closing. • Check for a short (staple in wire), replace as needed . • Disconnect wires at door control, touch wires together. If motor unit activates, replace door ... Diagnostic Chart 1 FLASH Safety reversing sensors wire open (broken or disconnected). Installed Safety Reversing Sensor Your garage door operator is not lit on the safety reversing sensors...

3900PLD Manual - Page 26

... door operator, the large button is factory programmed to pry open the case as shown. Within 30 seconds, press and hold the "learn" button on motor unit until the door has closed by...adjustment or modifications of eight Security✚® 315 MHz remote controls can be programmed to the door closing will blink. 4. To Add or Program a Hand-held remote control. Release the button when ...

3900PLD Manual - Page 27

... optional Keyless Entry must be programmed to close the door even after it may authorize access by ...Enter. To set a temporary PIN You may be used to operate your garage door operator. Within 30 seconds, enter a four digit personal identification number (...the existing PIN is installed, the light will no longer open the door. The operator light will blink three times. Release the ...

3900PLD Manual - Page 28

... LED comes ON. 2. Follow the instructions below to operate with the door operator. Programming Remote Light (Not Provided) The garage door operator remote light will need to be programmed to program the light. 1. Press the "learn button" on . 28 Activate the door using the Single Button Control Station (or hand-held remote control or...

3900PLD Manual - Page 30

... obstructed. Also can be mounted below the torsion bar in their door operator remote or from being manually opened once closed. 30 This temporary password can add a temporary password for visitors... floor. 475LM 377LM Keyless Entry with Security✚® : Enables end user to operate door operator from outside by entering a password on a work light from their car with their home...