I have been trying to repair Stanley t300 garage door, just put in a new
Now what is happening is that when I push the button, motor turns for a
few seconds then goes into reverse for a few seconds.
I have disengaged the worm gear from the other gear to see if there was
some obstruction, but same thing is happening.
Could anyone provide help or guidance on what it could be, just spent $45
buying the new housing which shattered when the beam fell, but at the time
motor worked fine.
Or could he have accidently moved one of the limit settings, eg the
force, when making the repair? Seems more likely something is binding
though, because I would think even with the force set to lowest, with
door connected, it would still run. And if something other than
stopping it, eg light beam sensors, then I don't think it would start
Actually I have seen some of them start to move and then decide that a
sensor was tripped and revrese. Worth checking. Along with
confirming that the sensor wires are connected properly. Mine here at
this house is so old it doesn't have those so I always forget about
Have you checked the screw jack mechanism attached to the gearbox? It
operates the limit switch on the circuirt board (thing sticking over
the long slot cut into the board) through two adjustable plastic tabs
(they're what adjust when you turn the small knobs on the bottom of
the opener to set the limits of door travel) and attaches to the rear
of the board through 4 screws:
The limit switch can be manipulated manually with a chopstick or
plastic pen (don't use metal, as there's exposed high voltage in the
opener, including at some spots on the circuit board) to make the
opener stop or start. Could this screw jack have come unsychronized
when you fixed the gearbox? BTW if you remove the screwjack to check
the motor, the motor won't run forever but will probably stop in 15-30
seconds because there's a time-out safety feature.
Unless the Stanley T300 is from the 1980s or earlier, it measures
force by measuring the motor RPM with either a round magnet or a
slotted cylinder on the shaft. Could the sensor for it be bad?
Optical sensors get dusty, but all sensors can have problems because
of poor wiring.
How's the motor capacitor? It's a cylinder about 1-2" diameter, 3-5"
long. If it fails, the motor will barely run.
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