Chamberlin 1/2 hsp lift master travels 12" stops goes back home

[Skyline69]

My chamberlin 1/2 hsp lift master when you press the garage door opener it travels about 12" and stops then goes back home. If I disengage it (pull the ripe) so it travels freely it still goes about 12", stops and goes back home. I have checked the door tension and the springs are fine. What else can I check?

Thanks in advance!!

[TJR]

Do you know how old the LiftMaster is?
Have you had any problems with it before?
Is it a chain drive or belt drive?

[Skyline69]

Do you know how old the LiftMaster is?
Have you had any problems with it before?
Is it a chain drive or belt drive?

Thanks fir replying. It's 6 years old and chain driven. I'm pretty technical. I went to Chamberlin Lift masters web site and did some diagnostics. It is flashing 5 amber lights at a time and appeared my sensor was bad. When I looked at it I pressed the connector tight and checked to see if I had short I didn't see anything weird but it's working now. Either I had a loose connection, short or the sensor is going bad. I'll have to keep an eye on it

[TJR]

So when it go back to full open the work light will blink and you can hear a clicking from the motor? That indicate safety sensor interrupt, some blocking sensor to wire connections and/or bad logic board, but as you did check it all before spending the $$$.
If the work light didn't blink and no clicking from the motor, it might be a bad rpm sensor and/or logic board.

[Skyline69]

Hmmm why would "anything" be bad? It's been working now going on day 3 with no issues

[swiftgarage]

if its not the travel limit, it might be the sensors