Question about Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+

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Chamberlain GDO Model# 41A3519-1 Power surge blew .01M capacitor next to light relay. Can I successfully test 4.5VDC transformer in-circuit?

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The keypad intermittently does not function. will waitt several minutes between coding and it still doesn't functioon. however, when trying to troubleshoot, the keypad functions normally. Any ideas???

Posted on Sep 07, 2010

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No reason why you can't check the transformer. Check the printed circuit for burnt or missing traces. That is common with power surges.

Posted on Feb 05, 2010


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After a power surge my garage door openers both quit working. The outlets are both getting power. The power surge came from outside the home.

Power surges love logic boards. You should remove the boards and check for burnt or missing traces on the printed circuit. Especially around the small transformer.

Aug 26, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+: There was a transformer explosion in the street, ...

There is no fuse in your opener. The logic board is very susceptible to power surges. You can pull it and check for burnt or missing traces on the printed circuit.

May 18, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Chamberlain Liftmaster GDO just clicks, no lights no open/close

Pull the logic board and check it for burnt or missing traces on the printed circuit. Thunderstorms love logic boards.

Apr 25, 2010 | Sears Craftsman LiftMaster Chamberlain...

3 Answers

I have a Craftsman 1/2 HP Garage Door Opener part # 41A4315-7. The D.O.C. cert # is K1027 and the date is 3/93. Several months ago the garage door opener ceased to function. I do not remember the symptoms...

I was not at all pleased with the service provided by FixYa.
I spoke to two different professionals and their responses did NOT help me solve the problem.
Their responses sent me on a time wasting series of steps that were not productive.

Both pros told me the problem was probably with the motor in the Garage Door Opener.
One told me I had to remove and disassemble the motor to read the windings with a multimeter.
I’m glad I didn’t follow his instructions.
Based on two pros telling me it was the motor (which I did not believe) I did a test.
Here was the process for testing the motor:
This is a dangerous process for a person with limited skills.
The test is done with the GDO in place, the cover removed, chain disconnected and power unplugged.
You will need a standard electric appliance power cord with either a two or three prong plug (pigtail).
The other end will be bare wires.
I used a 2 prong cord removed from an old steam iron but any power cord will work.

Remove the white supply wire from the light bulb socket in the GDO.
Attach one lead from the power cord to the white lead and cover all exposed copper wire or connector with insulating electrical tape.
If you are using a 3 prong plug, fold the green ground lead back out of the way and tape it to the power cord.
Make sure the remaining bare wire lead is not touching your body on anything metallic, then plug the power cord into the same socket you would plug the GDO.
Carefully touch the remaining HOT bare wire lead to either the RED or BLUE leads from the capacitor to the motor.
The motor should run.
Mine did just fine …. Nothing wrong with the motor.
I then touched the HOT lead to the other (Red or Blue) capacitor lead and the motor reversed direction …. Perfect.

I don’t know if this is a valid test of the capacitor, but I then touched the bare HOT lead to the Red then the Blue leads INTO the capacitor.
Again the motor ran fine and reversed direction.
I deduced that the capacitor was also working.
There is very little clearance for this last step so do it carefully.

After verifying the motor and capacitor were not the problem I started retracing all other power supply factors.
Ultimately I found I had reversed the bell wire leads from the door safety sensors when I reinstalled the GDO.
I had connected the hot lead from the left sensor to the right sensor input.
This is very easy to do because the two leads are identical.
The GDO will not operate with these leads reversed.
I corrected the connections and the GDO now works perfectly.
This could have been a 10 minute fix if either pro had asked the right question.
I don’t think either pro is aware of this requirement.

When I signed up for the chat the web site indicated I would be charged $12.99.
Now I find I am being charged 19.99 for bad information.
I doubt I will use your service again.

Jim Shane

Dec 01, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Dead Set after power surge

Check the power supply transformer primary driver transistor and the associated components (some diodes and capacitors, resistors, an optocoupler maybe) and the rectifier diodes (or a bridge) and capacitors at the transformer secondary, what you are looking for is a short circuit, however, the short may as well be in another section of the circuit board (a shorted component may sometimes have signs of damage caused by heat, but this is not a rule).

Hope you can find out what it is...



Oct 01, 2009 | Televison & Video

1 Answer

Sears Craftsman Gar. door opener won't respond

There isn't a fuse. You are going to need to remove the cover on the opener and find out where you are losing the power. Maybe a neighbor has a volt meter you could use. I would check the power cord and then the logic board. Makes no sense but I would check for burnt or missing traces on the printed circuit board especially around that small transformer.

Aug 11, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Craftsman GDO 1/2 HP - Remotes not working after storm

sounds like it blew the reciever crystal buy another and return the motor thats fried 4 refund

Jul 29, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Liftmaster gdo won't operate with door or remote

Hi there, when the problem first started was the door being used frequently? If your GDO was used quite a few time's in a short period of time the "overload" may have triped. The makers of all GDO's now adays install an overload witch is an electrical safety device protecting the motor. This prevents over heating in turn burning up the motor. To rectify unplug for 15-20 mins. If you have Model number 1270 turn to pg. 7 in owners manuel. Insure all door locks are free. Insure power to electrical outlets by pluging desk lamp in same out as GDO. what model do you have?

Mar 17, 2009 | liftmaster Chamberlain Garage Door Opener...

1 Answer

Liftmaster 1/2 hp fuse?

logic board cooked, replace board or entire unit. use a surge protector. homwowners insurance covers damage.

Sep 12, 2008 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Sony kp-57ws510

test your power supply output voltages, make sure the step down transformers are not leaking high voltage into the dc circuits. always start at the basics then work your way up or out. the most common problem for these late model tv's is power supply they just dont use quality parts anymore. in older tv's you could hear the high voltage arcs, snap today its rare for that to happen. I have a 32 inch LCD here now that actually blew a 1500 pico farad capacitor with no noise. that amazes me thats a pretty good sized capacitor, and they usually make some noise when they blow the top right off of them.

Nov 01, 2007 | Sony KP-57WS510 57" Rear Projection HDTV

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