OT: Fixed my garage door opener!

Last winter one of the garage door openers stopped responding to the remote. After a week or two we had a cold snap and it started working again. Then
not, then OK, more or less in sync with low temperature days. "Cold joint" says I. Then it finally died completely. Sears.com wants $85 for a replacement board (! you can buy a whole new opener for $135), so we lived with it through the summer as higher priority projects took precedence. Yesterday I tracked down the documentation, that includes a circuit diagram, so I finally took the board out and began searching for a cold solder joint. Found one: the pin on the connector that connects common on the board to the actual ground. Perhaps that could interfere with the RF reception. Resoldered it, but after reassembling the unit, found it didn't help. Got out the old Tektronix 'scope, climbed up the ladder, tied the scope onto a step and started systematically checking for signal. Eventually traced the signal from the RF receiver through signal conditioning to the input to the decoder chip. Signal goes in, right code, nothing comes out. Looked like an $85 part after all, 'cause I wasn't going to bother unsoldering the chip and finding a replacement. Before giving up, however, I moved all the DIP switches up and down a few times on the off chance that it was a poor connection inside the switch. That was it! Works fine now. Saved some bux.
Now, the opener on the other door, on which I did replace the board a few years ago, reads the code from the transmitter and memorizes it. No DIP switches. Unfortunately, ever few weeks it forgets the code so you have to do it again. A pain in the butt, but not worth replacing the board again for. If I can find a circuit diagram, perhaps I'll go after that problem too. It's been a long time since I trouble shot a circuit board. I'm inspired. -- Bob (Chief Pilot, White Knuckle Airways)
I don't have to like Bush and Cheney (Or Kerry, for that matter) to love America
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Yep! Dip switches are a reasonably common cause of garage door opener problems. It is a good idea to occasionally work the dip switches through several operations to "clean" their contacts. Just don't forget the code that is set in the dips so you can restore both TX and RX to the same code. If you do happen to forget, just make sure the same "new" code is set on both.
Bob Swinney

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Glad to hear you fixed the dip switch problem.
The next time it loses the code erase the memory on the logic board (hold smart button til LED goes out), re-program transmitter(s), then unplug unit for 15 seconds & plug back in. This usually solves the problem of the board dropping it's memory.
Doordoc www.DoorsAndOpeners.com
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Bob Chilcoat wrote:

Deja vu all over again!
My old Craftsman opener had its power xformer mounted only by its soldered pins - to a vertical pc board. After a couple of years of sitting next to a vibrating motor one of the solder joints cracked. Pretty easy to find and resolder, and I rigged a hold down clamp to keep the xformer squeezed against the board while I was at it. It's been at least a dozen years now and the damn thing's still working fine.
I'm repairing less and less electronic stuff these days because its so much more reliable than the vacuum tube stuff I started out working on. I find that most problems these days fit in the category of "poor connections" of some kind, and quite often those are cracked solder joints. Rarely are the problems I'm finding caused by actual failed components, thpough I did have to replace four power hexfets in young son's car stereo amp last week because he overdrove it to the point where they actually "blew out".
The bible teaches that in reference to the dead you should only say things that are good:
Arafat's dead.
That's good.
Happy Holidays guys!
Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)
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On Wed, 24 Nov 2004 19:05:55 -0500, Jeff Wisnia

<snip>
Alleluia!
Pete Keillor
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I had an opposite problem the last several winters with our Chamberlan garage door opener. It would work by remote, but the pushbuttons would not respond. Somewhat by accident I eventually found that it would work if I removed one or more of the three lighted pushbuttions I had wired to the opener. Apparently the power supply was so marginal it would barely handle the three light bulbs in the pushbuttons. When the temperature dropped much below 30 degrees F the power supply would not handle the load. Talk about cutting the design close. Has continued to work fine with only one lighted pushbutton and two unlighted ones.
Mill

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