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Full disclosure, I'm not an electrician by any means. My dad was an electrician in the Navy, but we lost him last year. Since I don't have him to look to anymore, I'm hoping I can find some help here.

I have a little set of remote-controlled AC outlets (not smart, just remote-controlled). One of them stopped working a while back, and since they don't make them anymore, I pulled it apart to see if I could fix it.

I discovered what looks to my mostly ignorant eyes to be a fried diode (pictured below) and I pulled it out. My problem is I don't know what to get to replace it. I also hope someone can tell me where I could buy one, worth only pennies, without buying a hundred, or paying a thousand times its worth in shipping charges.

Since there is no decipherable writing on the part itself, but there is some on the board around the part's location, I'm including a pic of that as well. I think it says:

[Line 1] RF-DY-064-B1-V1 0

[Line 2 - by diode symbol] ZD2

[Line 3] 31VO

[Line 4] E314348

[Line 5] (FILLED TRIANGLE) 94V- O

O's may be 0's and vice versa. They don't appear to have used theta lines to differentiate. I also think the logo to the right says "LOMBER".

Let me know if I can provide anything else that might help.

Any direction you could give would be appreciated.

part itself (diode?)

part location on circuit board

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  • \$\begingroup\$ The ZD may indicate a Zener diode - if so, you would need to know the Zener voltage to replace it. Can you open another unit to see if you can see any markings on the diode in it? \$\endgroup\$
    – Peter Bennett
    Mar 10, 2022 at 18:54
  • \$\begingroup\$ There are no useful markings on the board except to identify it as a Zener diode, probably 400mW or 500mW from the package. What makes you think it is faulty? Does it measure as short, open or something else? There are many possible voltages and it matters. Are there any markings on the part itself? \$\endgroup\$
    – Spehro Pefhany
    Mar 10, 2022 at 18:56
  • \$\begingroup\$ The symbol indicates a zener diode. 94V-0 is a flammability rating for the board; E314348 looks like a UL file number \$\endgroup\$
    – user28910
    Mar 10, 2022 at 19:30
  • \$\begingroup\$ Zener diodes don't get fried themselves for no reason. If the zener has been fried, it means there is a fault somewhere in the circuit that causes the zener to fry, and replacing a new zener will just get fried too until the fault has been fixed. Maybe it would help to even know what the zener was doing in the circuit. \$\endgroup\$
    – Justme
    Mar 10, 2022 at 19:50
  • \$\begingroup\$ I assumed the diode was the problem because the board looks burned around it, and both ends of it touch the plastic cover and charred it brown. My wall wart has skid marks in it's undies lol.. Looking at the other units, every one of them has those same skid marks though. So I pulled that diode for nothing. On further inspection/comparison with the working unit I opened, there is one spot on the back of the board where two contacts have apparently connected themselves somehow, but are separated in the unit that works. I've clipped those apart and will sit the diode back in & see if she works. \$\endgroup\$
    – DC3
    Mar 11, 2022 at 21:14

1 Answer 1

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Those boards don't need a whole lot of heat to discolor over time -- exactly as you've observed. They are made from a cheap phenolic resin material. The Zener diode is dissipating some power, and is running hot. Running hot won't contribute to its longevity, but then they are designed to operate like that. It's impossible to tell that it did fail (or not!) just by looking at the picture you provided.

You should measure the Zener voltage as well as forward voltage on that diode to ensure it's OK.

The diode doesn't look fried. The only text that would apply to that Zener diode is 31V0 - that would be the Zener voltage of 31V. The diode 1N5257B would be the closest equivalent at 31V4, but that's not 31V0. So it's highly probable that 31V0 doesn't apply to the Zener diode but is something else.

The easiest thing to do is to remove the Zener diode from the other outlet, and measure its Zener voltage. You'll need a 35-40V dc power supply, and a 1-5kOhm series resistor to do that.

The Zener diode that you've pictured doesn't look damaged. You can read the type directly from the glass body. There should be some black letters/digits there. Expect something like 1Nxxxxl, where xxx are 3-4 digits, and l is an optional letter.

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  • \$\begingroup\$ Weelllll crap. I assumed the diode was the problem because the board looks burned around it, and apparently both ends touch the plastic cover and charred it. My wall wart has skid marks in it's undies lol.. Looking at the other units, every single one of them has those same skid marks though. So I pulled that diode for nothing & have no idea what failed in this unit. Fuse isn't blown. Hm.. There is one spot on the back of the board where two contacts have connected somehow, but they are separated in the unit that works. I'll try clipping those apart and replacing the diode... 🤞 Thanks! \$\endgroup\$
    – DC3
    Mar 11, 2022 at 3:38

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