G Door Opener - intermittant operation - reset button

[jd99]

Sears Craftsman - 139-18851 1/2 hp (15 yrs old), chain drive

Functions perfectly up to 20 times. Then next day will not function at all - no buzz, no clicks, no flashing light. Neither from remote or hard wired switches.
Found small p.b. recessed on back panel (does not look like p.b.) which is not mentioned in any manuals. Upon pushing this button door works fine again. Obviously some type of 'Reset' button. Rotating shaft by hand also worked once.

Question is: if it's a reset what kinds of things cause it to trip ? Motor has some type of thermal protection but overnight cooldown not solving problem. (Maybe cooldown plus reset required ? ? ?)

Drive worm gears are OK, limit switches OK, photo cells lined up, chain is lubricated, no measruable misalignment of chain or wheel tracks .

Worn brushes wouldn't be fixed by 'Reset".
Does motor need lubrication?

Desparate - this has been going on for a month. Bought new unit on sale yesterday, but would prefer to fix existing rather than have to replace tracks and chain as well as operator - apparently new chain sprocket not compatible with old ? ?

[HayZee518]

the motor is the induction type - doesn't use brushes. the reset resets the computer chip. a thermal overload is assembled within the motor windings. if there is binding in the drive train, motor amps go up and the motor heats up tripping the overload. the up - down force switches limit the travel if the door should hit an object. in the down travel the door instantly reverses back to full open. the electric eyes are a permissive that lets the door open or close unless the eye's path is broken.

[jd99]

Thanks.

Still would like to know what things would cause chip to require 'reset'. I'm assuming it's not motor overload as this is supposed to automatically reset after 15 minutes.

Travel switches and photo eyes function correctly.

[gdoorpro]

I am not familiar with a reset on any craftsman operators, and am not familiar with that model number, but here is my advice.

Any garage door operator, especially a chain driven one that last 15 years is pretty good these days. You could fix it by replacing parts, but will probably have other issues in the near future. So replacing it would be financially the best option over time.

As for this unit, my guess would be you have a faulty circuit board, probably worth $90 or so. I sell LiftMaster units which are pretty much the same as the craftsman, so I am familiar with the products. I rarely sell the chain drives though, because the belt drives have fewer repair issues. So I recommend the belt drives, and a DC motor with a soft start and stop, which is gentler on the door.

As a dealer the cost difference for me beetween a belt and chain drive can be as little as $10 to as much as $35 depending on how i buy them. Over the long haul, it will save you money to get a good operator.

Ryan

[jd99]

SRT button
Thanks Gentlemen, your info has helped. I live on an island, service difficult.

Found reference (in French section of manual) to SRT button located where I saw it - apparently required to reset radio transmitter codes. Doesn't explain why it works to make door work on hardwired buttons.

Suspect opener brain is fried somehow. Replacement card quoted at $119 cdn plus shipping & taxes = $131. Sears had sale ending yesterday so went ashore and bought complete new operator for $180.

Enough fooling with this, going out to exchange units now. It's a chain drive, I'm hoping that chain and track are same size so won't need to replace whole thing.

[jd99]

FYI - New Craftsman easily replaced old unit.

Chain and sprocket of new unit were same as old unit - as I had hoped. Contrary to what Sears Service people told me. Bolt patterns even the same. So didn't have to change out track and chain and all the bracket hardware. Pushbuttons and photo-cells OK as is. Pretty much plug and play. Old remotes don't work with new 'rolling code' system.

Now have large box of spare parts.

Took me about 4 hrs to change out operator unit, but could easily do it in an hr next time.