On Mon, Nov 10, 2008 at 1:58 PM, Wayne <wmc_st@xxiii.com> wrote:
> David Scheidt wrote:
>>
>> We've got a Sears garage door opener that's gone tits up. It starts
>> to turn the motor, moves a little bit, then gives up, flashing the
>> light socket. The photo eyes have the lights lit they're supposed to,
>
> I have a 1999 production Liftmaster / Chamberlain opener which is probably
> almost identical with yours. It started doing similar stuff last spring. I
> discovered parts and entire motors or "head units" are readily available on
> ebay. I bought a gear kit for about $28 with the whole shaft and worm gear
> assy.
>
> What turned out to be the real problem was the housing had a bunch of
> vegetation (from bird trying to build nests on top!) and dead bugs. When the
> thing fired up, the air movement kicked up this mess and it got into the
> optical sensor that detects jams, and tripped it. You can probably pull the
> front end cap off it, without taking it off the ceiling, and vacuum out the
> crud to see if that helps.
>
> I cleaned out all the crap, replaced and lubed the gears, reflowed solder on
> the circuit board, put it all back together and adjusted the chain (hint -
> grab your calipers and find a 1/2" OD deep-well socket and use as a feeler
> gauge for the chain tension.)
>
> If you mess with the electronics, the circuit boards are coded by the color
> of the "learn button" (red, purple, etc)
>
> -Wayne
>
I took the bottom cover off. No stripped gears (they've still got
grease on them!), rpm sensor eyes are clear (I even cleaned them),
limit switches aren't jammed. I can rotate the motor shaft by hand,
and it feels smooth, with no notches or slop. That says "electronics"
to me. New logic board is $90, available next week. New opener is
somewhere between $150 and $300, can get it today. Wonder if they
still sell one that will fit all the mounting brackets?
--
David Scheidt
dmscheidt@gmail.com
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