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Trying to identify a (zener?) diode

SamBushman

May 4, 2023
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I'm currently working on the power supply for an old computer monitor (circa 1991). Among the components are 3 diodes that, based on appearance, I think are Zener Diodes. I have been trying to figure out the specs for these diodes, but the markings don't seem to follow the patterns I've seen referenced online. The diode has "2262" printed on it.
Zener Diode.jpg

As a bonus, I'd love to know how to test it. Looking online, it sounds like once I know the specifications for the component I could run voltage through it and measure with my multimeter.

Thank you for any advice and your time.
 

Delta Prime

Jul 29, 2020
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is that the best one the one with the clearest markings on it that are legible. That is correct you can test it just as you said .but I would take it variable power supply increase the voltage slowly until your meter stops at a particular voltage while you increase slightly past that voltage so you have to do it slowly cuz it will pop on you and it is glass and it'll shatter on you, go right into your eyeball . but you have to remember that black band is actually where positive of the power supply goes too. zener diodes work in reverse bias as they say. You could also just check continuity
With your multimeter put the positive lead on the black band which is the (cathode) and the negative lead of your meter on the other side the (anode) and if you get infinite or zero on your meter it might be a regular diode flip it around and see if there's continuity you should have continuity you hear a beep on a continuity test and probably 0.6 volts on your meter if it has a diode test capability if it's a regular diode. definitely glass passivated package style D015
This is as close I can Come up with. Wait a minute the way you're holding it it looks like 2,1 or 2N can you roll it around?
 

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SamBushman

May 4, 2023
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0607232134.jpg0607232135.jpg0607232135a.jpg0607232136.jpgTried to roll it around a bit. Hopefully you can see it says "2262" on it.
 

Delta Prime

Jul 29, 2020
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Yeah okay you got it 2262
Go ahead and test it.
I'm sorry would you like help with the data sheet but it independent of the data sheet we can test it real quick go no go test to see if it's a regular diode or a zener diode as I stated above very long winded apologies
 

Delta Prime

Jul 29, 2020
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Getting late I can stay another 15 minutes if you'd like to test it now. If you have any questions I'll be here where I'm at it's 10:15 so 10:30 I'm gone
 

SamBushman

May 4, 2023
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I won't be able to tonight unfortunately. Please don't keep yourself around late on my behalf. I'll read through the advice you've offered more closely later in the week and respond with how I'll want to try and proceed.

Again, thank you very much for the offer. I'm surprised and humbled by your responsivness and interest.

Best wishes and have a good evening
 

kellys_eye

Jun 25, 2010
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If it tests like a diode then it's probably just fine - irrespective of its potential breakdown (zener) voltage.

Do you have the schematic of the power supply or pictures of it and/or the circuit board?
 

danadak

Feb 19, 2021
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To test use a 1K R in series with diode.

Then apply ~ 2V to that series circuit of diode and R, + to non band end, anode, thats forward bias
direction. In that direction across diode you will read ~ .7. Thats the upper right quadrant in below graph.

1686222312927.png



Now change R to ~ 5W, 10K ohms. If you do not have a 5W R, use 5 1W Rs, 2K ohms each. Basically
keep the power dissipation within reason on each R. Caution you will be using HV possibly in this test.

Then apply ~ 2V to it, + to band end, thats the Zener breakdown direction, reverse bias, lower left
quadrant in graph below. Now increase slowly the V and see if it "clamps" at some V, where it changes
very little as you raise V. Thats the "region of voltage regulation" in graph below. Given its a monitor I
would not go past 200V or so trying to get it to clamp, eg. act as a zener. Note the V will change a little
in this region with rising V but is "relatively" fixed. Stop raising V once you see this region as resistor
will start getting hot if you keep raising V.

1686221689478.png

Regards, Dana.
 
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SamBushman

May 4, 2023
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Apologies for the late reply. So tl;dr, I ended up taking an educated risk and reinstalling the diode and along with some other replacement parts. I lucked out and am up and working.

This zener diode was a part of a power supply for a CRT computer monitor that experienced capacitor leakage from every single electrolytic cap, some resulting trace corrision, and a faulty non-zener diode (it tested short in both directions). My question came from me being suspicious of the other diodes after finding the first failed one.

I could find no schematics for the monitor, I lack a bench power supply for testing voltage through the component, and couldn't find a data sheet for the zener as its part number doesn't follow the conventions I see online. The one failed diode was right next to the worst of the cap corrosion damage, and all the other non-zener diodes tested fine, so I just reinstalled the zeners along with the tested diodes and my one replacement. The monitir fires up, so I guess it was good.

Thank you everyone for the help. I have certainly learned a lot from this thread.
 

Delta Prime

Jul 29, 2020
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Thank you everyone for the help. I have certainly learned a lot from this thread
I helped the most! :p My crystal ball knew you had leaky capacitors even though you never mentioned capacitors so let that be a lesson to you. What that is I have no idea. But...My crystal ball does... ;)
 
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