Help identify a Zener?

[alwalker]

Re: Help identify a Zener?

I have two Liftmaster garage door openers and they both now have the 990LM surge protectors wired into them. I was a little curious about the protection going to the safety sensor and opener switch so just to see the answer I would get I sent an email to Chamberlain/Liftmaster asking (1) why the 990LM was discontinued, (2) if they had a schematic of the 990LM itself available and (3) if it protected the logic board or if it actually protects the safety sensors. Here is the response I got:

Thank you for contacting Chamberlain Group Technical Support. We sincerely apologize for the delay in our reply. Please see below for a response to the inquiry you recently submitted on our website.

Hello, I will be happy to assist you. Unfortunately, we no longer have schematics for the 990LM surge protector. Details as far as why it was discontinued have not been given. The wiring to the safety sensors and to the motor was protected while using the surge protector.

After dismantling the 990LM we now have a very nice schematic courtesy of Redwire. I don't believe that Chamberlain does not have a schematic of the unit even though that is what I was told. I also do not believe that the 990LM protects the sensors--at all. Hopefully it will protect the logic board if a strike comes through the rails and wiring. I already knew that the surge protector does not protect the sensors since I experienced lightning damage to the sensor when the 990LM had already been installed. Sometimes it's just fun to ask questions of manufacturers when you already know the answers will be either irrelevant or incorrect.

[sam_sam_sam]

Re: Help identify a Zener?

I have two Liftmaster garage door openers and they both now have the 990LM surge protectors wired into them. I was a little curious about the protection going to the safety sensor and opener switch so just to see the answer I would get I sent an email to Chamberlain/Liftmaster asking (1) why the 990LM was discontinued, (2) if they had a schematic of the 990LM itself available and (3) if it protected the logic board or if it actually protects the safety sensors. Here is the response I got:

Thank you for contacting Chamberlain Group Technical Support. We sincerely apologize for the delay in our reply. Please see below for a response to the inquiry you recently submitted on our website.

Hello, I will be happy to assist you. Unfortunately, we no longer have schematics for the 990LM surge protector. Details as far as why it was discontinued have not been given. The wiring to the safety sensors and to the motor was protected while using the surge protector.

After dismantling the 990LM we now have a very nice schematic courtesy of Redwire. I don't believe that Chamberlain does not have a schematic of the unit even though that is what I was told. I also do not believe that the 990LM protects the sensors--at all. Hopefully it will protect the logic board if a strike comes through the rails and wiring. I already knew that the surge protector does not protect the sensors since I experienced lightning damage to the sensor when the 990LM had already been installed. Sometimes it's just fun to ask questions of manufacturers when you already know the answers will be either irrelevant or incorrect.

This is unacceptable and unfortunate that this company has this attitude about there product and surge protector device which must have been discontinued because then that way they can make more money on replacement parts or the hole unit

[sam_sam_sam]

Re: Help identify a Zener?

Not sure where the part number is not working? The 990LM schematic is just a picture. I could post a bill-of-materials if you are making one.

If I lived in Florida or Texas I would definitely have lightning protector on the garage door opener.

Could you please do that for me because I want to add this to my garage door openers because I have had lightning strike one of the opener more than once

One time it fried the door sensors another time the same thing and the controller board as well and the door switch controller as well I also think it damaged the motor as well in some way because it would run very warm also the up/down force adjustment we're screwed up as well

That time I just replaced the garage door opener because the replacement parts were almost as much as a new one

[redwire]

Re: Help identify a Zener?

I think Liftmaster/Chamberlain made a design mistake so the sensors are susceptible to lightning damage. The sensor mounting bolt arcs to the PC board and kills them. I think this is because the mounting bolt/bracket is grounded to the garage door rails yet the opener electronics is grounded to mains ground.
It seems suspect the sensor PC board has traces around the mounting bolt- when you actually want lots of clearance instead.

This might be why the 990LM did not work- lightning zap happens at the sensor mounting bolt and the lightning protection module is a mile away, it's over at the opener. I wonder if adding a thick ground wire to the door rails would help, but to what? The pad? or Mains ground? It's hard to know if the rails/door are the antenna for the discharge, or the lighting surge comes in on mains.

[redwire]

Re: Help identify a Zener?

For the Liftmaster 990LM possible bill-of-materials:

where				Qty		Description				mfgr		p/n		Mouser		Digi-Key
								
								
Sensors				2		TVS DIODE 1,500W 33.3VWM 69.7VC DO-201	ST		1.5KE39A	511-1.5KE39A	497-6607-1-ND
								
								
Neutral-GND			1							Original	GNR14D431K				
						MOV 275VAC 6kA Disc 14mm 		Bourns		MOV-14D431K	652-MOV-14D431K		118-MOV-14D431K-ND
						MOV 275VAC 6kA Disc 14mm 		TDK Epcos	B72214S0271K101	871-B72214S271K101	495-1412-ND								

Line-Neutral and Line-GND	2				need thermal fuse	Original	GNR20D431K				
						MOV 275VAC 10kA Disc 20mm Thermally Protected	Littelfuse	TMOV20RP275E		576-TMOV20RP275E		F4042-ND
						MOV 275VAC 10kA Disc 20mm Thermally Protected	Eaton		MOVTP20V275N		504-MOVTP20V275N 		283-MOVTP20V275N-ND
													
								
Sensors ground			1		Original	GNR14D201K				
						MOV 130VAC 6kA Disc 14mm		TDK Epcos	B72214S2131K101		871-B72214S2131K101 		495-1436-ND
						MOV 130VAC 4.5kA Disc 14mm		Bourns		MOV-14D201K		652-MOV-14D201K 		MOV-14D201K-ND
						MOV 130VAC 6kA Disc 14mm		Panasonic	ERZ-V14D201		no stock			P7217-ND

[alwalker]

Re: Help identify a Zener?

I think Liftmaster/Chamberlain made a design mistake so the sensors are susceptible to lightning damage. The sensor mounting bolt arcs to the PC board and kills them. I think this is because the mounting bolt/bracket is grounded to the garage door rails yet the opener electronics is grounded to mains ground.
It seems suspect the sensor PC board has traces around the mounting bolt- when you actually want lots of clearance instead.

This might be why the 990LM did not work- lightning zap happens at the sensor mounting bolt and the lightning protection module is a mile away, it's over at the opener. I wonder if adding a thick ground wire to the door rails would help, but to what? The pad? or Mains ground? It's hard to know if the rails/door are the antenna for the discharge, or the lighting surge comes in on mains.

I would think the mains ground. I wish I had an easy way to install an extra ground rod near the basement opener. That one is furthest from the electric entrance panel. BTW--I did check the condition of the ground rod and wiring at the meter. No problem there. I do suspect since the opener I have had the most lightning problems with is the furthest from my electric panel and that ground rod another ground rod directly attached to the rails might do the trick. I wish I could do it easily in the basement without tearing up the concrete floor to add a ground rod. It's doubtful the wife would approve