Garage Door Opener Repair

I am attempting to repair a Craftsman 1/2 HP door opener. The problem is around the obstacle sensors. The symptom is the classic "goes up but will not go down". I have disconnected the actual door and the unit still acts the same. I have replaced the sensors, checked the sensor wiring and can only get one sensor's light to light. The voltage at the terminals on the drive unit is about 3V and it should be about 6V, when comparing it to the adjacent door. Before I replace the drive unit's logic card - any suggestions?

Thanks,
LT

Greetings LT, weocome to the Foum.

I don't have an exact answer for your problem, but, given that Craftsman GDO's are made by Chamberland, here's a Link and I think they have a FAQ/trobleshoot at their Webpage, give it a try !

http://www.chamberlain-diy.com/diy04/home/

Welcome again,

Have a good Day !
S.W.

Post edited by: SWHouston, at: 2008/10/07 23:11

One optical sensor is normally a LED, a light output with a lense.

The other sensor is a lense and a light input device.

The circuit works because it assumes if the beam of light is broken something is in the way. But the beam only needs to go in one direction.

If one is 6V and one is 3V that doesn't necessarily mean it's bad.

My Craftsman 1/2 has two green LEDs one on each driver/sensor unit. The one on the driver unit is always green. The other is only lit green when no obst is in the light beam.

Perhaps someone moved accidentally the drive unit or sensing unit.

Post edited by: jmborchers, at: 2008/10/08 01:18

Yes, I think the sensor is not seeing the source light. Maybe it was bumped. You need an alignment procedure for this.
I guess you could check this by putting the sensor a few inches in front of the source light and see if the door is fooled into coming down.

Thanks for your responses. I have a bit more information. The send and the receive sensors have been replaced with the neighboring door's sensors. The wiring has also replaced. The alignment was difficult because of the "3 Volt" issue. I did manage to get them aligned but the light on the receiver would dimly go on. The sender's light is also very dim so I believe the problem is the logic board, which provides the power. Any additional suggestion / thoughts would be appreciated.

LVTurner

If you can post a schematic we can help troubleshoot this.

If you noticed that replacing with a known good part gives you a dimmer led light I think you're going in the right direction.

If you could swap boards then you'd have a real advantage. You could be able to measure the voltage supply between the known good one and the suspect one. If they are different then you know that part is bad.

Post edited by: jmborchers, at: 2008/10/09 01:26

Didn't think of that but that is a very logical next step. I will perform this and report my results.

The swap worked so the new board is on its way. Thinking back on the diagnostic work, it had to be the board because of the 3 volt situation when it should have been running at 6v. Thanks for the advice and assistance.