Capacitor Blown On Sears GDO?

I have a 139.53xxx garage door opener. There was lightning strike in the neighborhood and we lost electricity. Upon restoration of power, we found the GDO to be inoperative. Observations:
+ When one pushes either the wall button or a remote, there is a click from the GDO whereupon the light goes on and nothing else happens. No hums, nothing. + The light goes out after a few minutes as it should. + Blocking a sensor and trying again leads to the GDO light blinking, so that part of the system is working. + The light on the wall button is on at all times. + There is a little green light on the back of the board that I think has to do with the remote control. It blinks intermittently.
I'm thinking that something got fried inside the GDO. A new circuit board is $80 + shipping, which is a significant fraction of the cost of a new one. I did notice a big capacitor inside wired between the power coming into the device and the motor. I suspect it is there to give a shot of juice get the motor going when the button is pushed. It looks OK from the outside. At $18 or so it is worth replacing if this indeed is the trouble. Any ideas?
Roy
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Roy, I had a similar problem with a Stanley GDO. Except that the capacitor vented gas and was obviously blown. I replaced the capacitor and it worked. $18 for a capacitor seems very high. Most sears GDOs are made by Chaberlain. Maybe you can find a cheaper one with them directly. My guess is that you have more problems than just a capacitor. It's one of the more rigorous components. A lightning stike probably did damage elsewhere. IMHO

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The capacitor would not be the problem. You are correct that that it gives the motor it starting power. If the capacitor was bad you would here the motor hum as it is trying to run but can't. Circuit boards on garage door openers get blown regularly during lightning storms in some areas & I am fairly positive that is your problem also and that the part of the board that controls the open and/or close relay is where the problem lies. There may or may not be any obvios burn marks on the board. A power surge will usually fry parts but a static charge may not leave any obvious trace.
Chamberlain has just come out w/ a new surge protector that plugs into the outlet the opener plugs into. However it also has protection for the low voltage wiring that goes to the photo-cells & wall buttons also. Many times the board gets taken out by static charges that "jumps" onto these low volt wires & has nothing to do w/ an incoming power surge on the electrical wiring. Electricity will always seek the closest ground & all the wiring going through a garage to a close circuit board makes it an easy path to find.
Doordoc www.DoorsAndOpeners.com
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RJH wrote:

Think fuse.
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Hi,
Missed the original post, but what appears to be a capacitor is actually an MOV. Intended to 'sacrifice itself', a hard spike will *violently* blow these apart.
The bad news is that the pcboard's transformer primary is also most likely blown open. I've been able to find the xformers available separately in a very few cases, but in most instnaces, it's better just to replace the GDO.
Hope that's of some help.
God bless,
Dave Harnish Dave's Repair Service New Albany, PA www.DavesRepair.com snipped-for-privacy@sosbbs.com 570-363-2404
I'm a 32-year pro appliance technician, and love sharing what I've learned - in a FREE Monthly Appliance Tips Newsletter. (Back issues now posted here too!) www.DavesRepair.com
John 3:3

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Sorry boss, The original poster stated that there was a light on the board... The unit is getting power, and the transformer is working.
Doordoc is correct as usual, but there may be a VERY slim chance that the opener could be revived. Unplug the unit for a minute and plug it back in. Once in a while it works, more than often not.
That being said, oftentimes lightning takes out more than just the board. All low voltage systems should be suspect. Photocells (if it has them), and RPM boards can be corrupted. While you're at it, you may want to check your sprinkler, and alarm system.
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Sears openers are made by Chamberlain Group, so try calling them (they have a toll-free number) and speaking with a technician (not an installation tech but an electronics tech). Tell them the symptoms, especially how the green light blinks (how fast, how many blinks in a row, long vs. short blinks, etc.) because it may be putting out a diagnostic code. Sometimes just unplugging the unit for a few minutes will restore function.

$18 seems expensive for that type of capacitor because it should be only about $5 an electrical supply. You can test it with just an ohmmeter, but test only with the AC power cord unplugged and with the capacitor removed from the circuit. First, measure the DC voltage across it (have your meter set on the 100V or higher scale) because it could retain a high voltage charge, and discharge it with a plastic-handled screwdriver across its connectors. Once this is done, set the meter to an ohms scale and measure its resistance, which should start out low but gradually rise to several megaohms.
I don't know anything about your model GDO, but unless it's 20+ years old it probably has a microprocessor on it, and failure of that component requires a new circuit board because the microprocessors are custom programmed and not sold separately. But all the other components are mundane and available inexpensively from numerous electronics supplies. Have you carefully checked the board, front and back, for burns, dark marks, cracked or vaporized components, or broken solder joints? Sometimes when the power goes out, some circuitry cools off for the first time in years and causes cracks, some which can't be seen except under magnification. www.repairfaq.org is a large FAQ about electronic repair, and except for the microprocessor, almost every component can be tested with just a volt-ohm meter. It's possible that the relay driver transistors have blown or a relay has welded its contacts shut.
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Thanks for all of the input. I tried the unplug-for-a-while trick and that did not help, though there was a "click" and the light went on when I plugged it back in. There was no overt evidence on the circuit board that anything was fried, and the premium-priced capacitor looked just fine. Base on my observations and the discussions, I conclude that something inside a component on the board got toasted. In our disposable society that means I get a new GDO rather than get it fixed. Is it a reasonable assumption that when I get a new one I won't have to install a new chain and track, rather I can use what's already there and take the track, etc. that comes with the new one and dump it in the attic? Roy

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The plug/unplug was just a shot in the dark. Like I said before, it usually doesn't work.
A new one will probably bolt to the old rail, but I'm not 100% positive. Some time ago sears switched to a square tube rail. It Would be fairly safe to say that chamberlin didn't change the bolt pattern just for Sears. If the old T-Rail one will match up, I actually suggest that you use it rather than the new one. The snap together square tube seems to have a few problems with the carriage unit chain breaking off, and the plastic slide getting hung on one of the two splices.
good luck
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