Help identify a Zener?

[eccerr0r]

Re: Help identify a Zener?

Thank you so much for this schematic, this will go a long way for me to figure out my garage door even if it's not the same. Looks like it too has a bad cap in these units. But anyway the schematic exposes quite a bit of information for me.

But it looks like D104 - if that's the unit that's having problem - appears to be a generic diode and you can replace it with anything. Looks like you have a 1N4001 or something like that, it should be fine... is it working?

Agreed that the LED itself may be damaged now, quite possibly as a result for D104 shorting, so watch for that.

Also it seems that there are no zeners on the board. D107 is the only zener in the schematic, and it looks like the PCB was designed for it, but not silkscreened on the front. It looks like there's a spot for it where "D104" is printed but there's no marking for the true D107. If you want to put in a 6V zener you can, and it might save you from it zapping again and having to fix it again in the future.

[tester272001]

Re: Help identify a Zener?

the only schematic I found was darn close but older for sure. Doe snot identify actual part VALUES for some components.

[tester272001]

Re: Help identify a Zener?

here is the front and back of the EMITTER
14LG47S-2C
I put a temporary DIODE in ther,e the original was shorted. This was flashover lightning/strike.

[redwire]

Re: Help identify a Zener?

Post pics of the board. I did schematics for a couple generations of Liftmaster/Chamberlain/Sears garage door sensors. It's a 150Hz pulse train of 38kHz bursts from an LM2903.
It's usually the IR receiver module that fails in cold weather.
Original is TSOP1238 and I've heard a TSOP33338 works for a replacement.
D106 is a 1N4148.

Liftmaster 14LG472-2B, 14LG472-1B, 14LG372-1B; did not finish a 14SR472-1B schematic.

[tester272001]

Re: Help identify a Zener?

Agreed. Is likely the LED. I see there are 2 primary LIGHT frequencies for IR leds (unless I can find a marking on teh IR LED) so I need to either try both wavelengths or see which one the IR receiver uses. it is a TPMS5380 receiver (38khz). I did have to replace a 6.2V zener on the supply so I wanted to check this one for proper voltage.

[stj]

Re: Help identify a Zener?

probably just the led failing

[tester272001]

Re: Help identify a Zener?

this is from an Emitter board of a garage door safety sensor. The IR led seems a little dim. It is proprietary by Liftmaster. No exact schematic around and of course no parts list. I cannot seem to cross reference this part. Even knowing it is National it seems TI does not provide any backward lookup for diodes, mainly I see other active components. If you have any TIPS I all all ears! thanks!

[eccerr0r]

Re: Help identify a Zener?

seems to be a custom part number, what/where did it come out of?

[tester272001]

Re: Help identify a Zener?

Bud, thanks for the feedback! N makes sense! I've seen the test procedure before and I can try that. But I suspect this device as bad. So measuring the voltage might not give me the voltage it is SUPPOSE to be but the defective one. That is why I wanted to lookup the device. Maybe now that I know is National Semiconductor I can look it up! THANKS!

[budm]

Re: Help identify a Zener?

That is not 'Z', the the 'N' logo of National Semiconductor.
https://en.wikipedia.org/wiki/National_Semiconductor

You can find out if it is 5V Zener or not by connecting 470 Ohms resistor in series with the Zener in question then connected them to 9V battery in reverse bias then just use Volt meter to check the Voltage on the Zener in question.

[tester272001]

I have been looking around for a xref to see what this zener might be. I think it might be a 5V zener but the markings are strange to me. Please see pic showing all sides. I cannot tell if the marking is Z05280029 or Z052B0029 or how to read this. Any help is appreciated.