Help identify a Zener?

[redwire]

Re: Help identify a Zener?

I posted a reply today but it seems to have vanished so typing it in again from memory.

Thanks for the teardown pictures of Liftmaster 990LM.
I drew a schematic for the Liftmaster 990LM and think it's a decent design and would use it if I lived in an area with lots of lightning.
The non-flammable insulating tape around the MOV's helps their heat get to the thermal fuse and pop it if the MOV's heat up. This was the way in power strips too for many years. It might be the liability that made Liftmaster discontinue these? Or they just want to sell you a new opener.

I did not know you already have one of these modules with the green LED out. Not sure if the TCO fuse popped or the LED died. Take it apart, do an autopsy I guess. If the fuse went, it should not have any power to the opener.

[alwalker]

Re: Help identify a Zener?

Take it apart, you know for the science
I'm wondering why Liftmaster discontinued the 990LM and if it is safety related?
Sometimes big corps don't want liability for MOV fires. I would want to know if the thing is safe.
Inside I expect three MOV's for mains surges, and four other parts for the control lines. Maybe a small MOV or TVS diodes. Maybe a fuse for the green LED.

P.S. Ha only recall is for new controls
https://www.cpsc.gov/Recalls/2023/Ch...d-Recall-Alert

I took one apart that I just received--only three screws and comes apart easily. The 990LM does not use MOV's that have a built in fuse. The main board has mov's m1 and m2 as GNR20D431K and m3 is GNR14D431K. It does sandwich a thermal fuse between m1 and m2 and tape it all with what I suppose is a tape that will not go up in flames? The board that goes to the opener sensors and control uses a 14D201K. Since failure of that MOV would not result in the indicator led not lighting up I think I will take that one down and look at it to see if the MOV poofed when the safety sensor emitter board was damaged. After looking at the circuit I'm not all that sure that the thermal fuse is sufficient to keep it from being a fire hazard. That could be why it was discontinued.

[alwalker]

Re: Help identify a Zener?

Take it apart, you know for the science
I'm wondering why Liftmaster discontinued the 990LM and if it is safety related?
Sometimes big corps don't want liability for MOV fires. I would want to know if the thing is safe.
Inside I expect three MOV's for mains surges, and four other parts for the control lines. Maybe a small MOV or TVS diodes. Maybe a fuse for the green LED.

P.S. Ha only recall is for new controls
https://www.cpsc.gov/Recalls/2023/Ch...d-Recall-Alert

I'll have to see if the 990LM comes apart in a way that lets me put it back together again. Almost everything made nowadays in China "snaps" together and I would hate to break a new working surge protector right off the bat. That might be the easiest way though to get the right values for all of the components--definitely harder to do when things get burned and blown up. If I take one apart I'll post photos. I should be getting it delivered later this week.

[redwire]

Re: Help identify a Zener?

Take it apart, you know for the science
I'm wondering why Liftmaster discontinued the 990LM and if it is safety related?
Sometimes big corps don't want liability for MOV fires. I would want to know if the thing is safe.
Inside I expect three MOV's for mains surges, and four other parts for the control lines. Maybe a small MOV or TVS diodes. Maybe a fuse for the green LED.

P.S. Ha only recall is for new controls
https://www.cpsc.gov/Recalls/2023/Ch...d-Recall-Alert

[alwalker]

Re: Help identify a Zener?

I don't see any teardowns or pics of the insides, to figure out the circuit.
Liftmaster 990LM/Chamberlain CLSS1 Garage Door Opener Surge Protector discontinued because new opener sales are down and lightning is up lol.
Liftmaster 41A5530 are add-on kits with two MOV's (Line-GND, Neutral-GND) seems to have no Line-Neutral MOV, similar to Wayne Dalton 252994 it is just a couple 150VAC 20mm MOV's. These connect to the control board terminal strips.

I'd suggest buying a decent mains surge protector to plug the opener into, or adding two or three (L-N, L-G, N-G) 20mm MOV's 150-175VAC rated, with built-in thermal fuse, someplace safe.

Littelfuse TMOV's which have a thermal fuse inside for added safety, same as:
Bussmann MOVTP MOVTP20V150N
Epcos/TDK ThermoFuse T20K150 or T20K175.

The 990LM also protects the sensors and switches against lightning, I would expect 4 MOV's or TVS to protect there, going to ground.

It kind of depends on how the lightning surge is getting into the house - through stikes to the powerlines (mains) , or ground strikes (ground).

Thanks for the info. I can still get new 990LM units on Ebay. I have 2 doors with Liftmaster openers and installed one last year on the one that always gets damaged every year or so. I believe I will purchase another one today for the other door. In the event one of them does absorb the brunt of our next lightning strike I will definitely take it apart just to see what the circuit looks like.

[redwire]

Re: Help identify a Zener?

I wonder if that's what is inside the Liftmaster/Chamberlain surge protector they sold for use with the openers? Do you perhaps have a schematic of that (990LM or CLSS1)?

I don't see any teardowns or pics of the insides, to figure out the circuit.
Liftmaster 990LM/Chamberlain CLSS1 Garage Door Opener Surge Protector discontinued because new opener sales are down and lightning is up lol.
Liftmaster 41A5530 are add-on kits with two MOV's (Line-GND, Neutral-GND) seems to have no Line-Neutral MOV, similar to Wayne Dalton 252994 it is just a couple 150VAC 20mm MOV's. These connect to the control board terminal strips.

I'd suggest buying a decent mains surge protector to plug the opener into, or adding two or three (L-N, L-G, N-G) 20mm MOV's 150-175VAC rated, with built-in thermal fuse, someplace safe.

Littelfuse TMOV's which have a thermal fuse inside for added safety, same as:
Bussmann MOVTP MOVTP20V150N
Epcos/TDK ThermoFuse T20K150 or T20K175.

The 990LM also protects the sensors and switches against lightning, I would expect 4 MOV's or TVS to protect there, going to ground.

It kind of depends on how the lightning surge is getting into the house - through stikes to the powerlines (mains) , or ground strikes (ground).

[alwalker]

Re: Help identify a Zener?

you got the sensor emitter fixed
For lightning protection, I would add a mains surge protector (two MOV's) or the opener might already have them inside on the control board but they are pooched. It was an add-on change for some manufacturers.

I wonder if that's what is inside the Liftmaster/Chamberlain surge protector they sold for use with the openers? Do you perhaps have a schematic of that (990LM or CLSS1)?

[sam_sam_sam]

Re: Help identify a Zener?

The LM2903D and the power led were all that I needed. Everything works. I will set aside the sensor kit that I purchased and use it if the next lightning strike does more damage than can easily be repaired.

Thanks for posting your attempt repair and successful repair of your garage door opener because I also have a lift master brand as well I will have to look into it issue with sensor issues it might be related

[redwire]

Re: Help identify a Zener?

you got the sensor emitter fixed
For lightning protection, I would add a mains surge protector (two MOV's) or the opener might already have them inside on the control board but they are pooched. It was an add-on change for some manufacturers.

[alwalker]

Re: Help identify a Zener?

The original was LM2903M. I already ordered some LM2903D ic's and the led from eBay. I think any of them will work that are 903 based although the LM2903DR would have been a better choice. I'll let you know how it goes.

The LM2903D and the power led were all that I needed. Everything works. I will set aside the sensor kit that I purchased and use it if the next lightning strike does more damage than can easily be repaired.

[alwalker]

Re: Help identify a Zener?

Yeah any of those IC's will work really. Is yours a Liftmaster?

Yes. If you ever want to attract lightning owning one of their openers will do it.

[redwire]

Re: Help identify a Zener?

Yeah any of those IC's will work really. Is yours a Liftmaster?

[alwalker]

Re: Help identify a Zener?

What number is on the old part? From the pic, your IC is in a SOIC-8 package.
TI LM2903DR or LM2903-Q1 (automotive rated).
On-Semi LM2903EDR2G, the LM2903M is obsolete
ST LM2903DT or LM2903W (has extra protection diodes) or LM2903YDT, LM2903D seems expensive obsolete.
Diodes Inc. LM2903S or LM2903QS (automotive rated)

This part has been around for many decades since the early 1970's so there are a zillion different ones today.
I would get a LM2903DR as a replacement.

The original was LM2903M. I already ordered some LM2903D ic's and the led from eBay. I think any of them will work that are 903 based although the LM2903DR would have been a better choice. I'll let you know how it goes.

[redwire]

Re: Help identify a Zener?

What number is on the old part? From the pic, your IC is in a SOIC-8 package.
TI LM2903DR or LM2903-Q1 (automotive rated).
On-Semi LM2903EDR2G, the LM2903M is obsolete
ST LM2903DT or LM2903W (has extra protection diodes) or LM2903YDT, LM2903D seems expensive obsolete.
Diodes Inc. LM2903S or LM2903QS (automotive rated)

This part has been around for many decades since the early 1970's so there are a zillion different ones today.
I would get a LM2903DR as a replacement.

[alwalker]

Re: Help identify a Zener?

I'm able to draw this schematic for the 14LG479 Emitter board. Please review for mistakes.
They deleted the surge zener diode that was present on early models

The Power On LED is any vanilla 3mm (T-1) size green that you can find lying around, or off eBay or Ali as penny parts. Sorry I thought it was the IR emitter LED you were after.
Note the board marking "BLK" is +ve voltage, (I think the wire colour is reversed, Blk strip goes to WHT?) it used to run off 6VDC as a current-loop supplied by the opener, giving 5.3V for the entire circuit after the reverse polarity diode D104.
The circuit has two oscillators, one for 150Hz and the other gated 38kHz.
I'd get a new IC and LED and try that, check the IR LED is not shorted as well, it should be OK.

LM2903D sub ok for the original LM2903M? Yes the IR LED is not shorted. I'm hoping just the power led and the IC will do for this board. Thanks.

[redwire]

Re: Help identify a Zener?

I'm able to draw this schematic for the 14LG479 Emitter board. Please review for mistakes.
They deleted the surge zener diode that was present on early models

The Power On LED is any vanilla 3mm (T-1) size green that you can find lying around, or off eBay or Ali as penny parts. Sorry I thought it was the IR emitter LED you were after.
Note the board marking "BLK" is +ve voltage, (I think the wire colour is reversed, Blk strip goes to WHT?) it used to run off 6VDC as a current-loop supplied by the opener, giving 5.3V for the entire circuit after the reverse polarity diode D104.
The circuit has two oscillators, one for 150Hz and the other gated 38kHz.
I'd get a new IC and LED and try that, check the IR LED is not shorted as well, it should be OK.

[stj]

Re: Help identify a Zener?

lightning generates a huge emp,
anything with a long cable run or a coil acts as a receiving antenna

[alwalker]

Re: Help identify a Zener?

One is the red power on led, the other transmitter infra-red LED is a vanilla 5mm part, around 940-950nm and narrow angle. Like Kingbright WP7113F3BT, or Wurth 15400594F3590.
If you post pics of both sides of the board I can add more info.

If you get low resistance it could be a shorted diode or the LED is shorted.
You can see the IR led light while looking at it with your cell phone camera, it's dim but tells you if it's emitting some.

I would look at replacing a few semiconductors on the board it you have the patience and the opener circuit is not toast. Does the manual switch for lights work? It shouldn't door close without a good sensor signal, for safety purposes.

Lightning strikes seem to come in mains power (to the opener) and then arc over to the nearest ground, like the garage door door rails. So it jumps from the sensors to the rail and can damage either or both ends.
Some garage door openers have MOV kits to add protection, if you live where it's a common occurance. That is a couple of MOV's like MOV-20D271K, each from line-neutral and line-ground at the opener.

Not that the color matters but this is an older style 1995 sensor and the power indicator led on both the emitter and receiver were both green. I have already determined the emitter board is the only problem by installing a replacement board. The receiver and logic boards are fine. I'm just trying to see if I can repair the old emitter board. The power led reads 15 ohms across it. I can supply power to the board and the ir led will light up but since the receiver does not recognize it I am assuming the comparator ic has failed. I could be wrong and it could also need to be replaced. I can probably come up with a replacement diode for the power indicator that would work since we know the voltage and current limiting resistors value but I had hoped someone would have known the best replacement or original specs for the power indicator led. I've had many of these sensors fail due to lighting over the years and also had the logic board damaged. I have been able to repair the original logic bd several times over the years but the last time it was hit the damage was too severe and I had to replace it. I have used a surge protector in the past which has not protected anything from being damaged. Last year I installed the Chamberlain surge protector they used to sell that may have some protection at the sensor lines in addition to the power for the logic board. In any case the surge protector did not trip this time but the safety sensor still did get popped.

[redwire]

Re: Help identify a Zener?

One is the red power on led, the other transmitter infra-red LED is a vanilla 5mm part, around 940-950nm and narrow angle. Like Kingbright WP7113F3BT, or Wurth 15400594F3590.
If you post pics of both sides of the board I can add more info.

If you get low resistance it could be a shorted diode or the LED is shorted.
You can see the IR led light while looking at it with your cell phone camera, it's dim but tells you if it's emitting some.

I would look at replacing a few semiconductors on the board it you have the patience and the opener circuit is not toast. Does the manual switch for lights work? It shouldn't door close without a good sensor signal, for safety purposes.

Lightning strikes seem to come in mains power (to the opener) and then arc over to the nearest ground, like the garage door door rails. So it jumps from the sensors to the rail and can damage either or both ends.
Some garage door openers have MOV kits to add protection, if you live where it's a common occurance. That is a couple of MOV's like MOV-20D271K, each from line-neutral and line-ground at the opener.

[sam_sam_sam]

Re: Help identify a Zener?

I have had this happen to my garage door several times in the past and have never been able to repair them but do not be surprised if the garage door controller is not damaged as well because this has been the pattern that I have seen in the past

Because I have had to replace the controller board and the door sensors as well