Diode identification please

[andyrlb]

Morning all ,
I’ve googled “ how to identify a diodes value “ and soon discovered that it’s all beyond me so I’m hoping someone can help me out here .
I cannot find a schematic so this is my only option for knowing it’s values .

https://uploads.tapatalk-cdn.com/20200926/3345b50af70d0440dc89455964f5a158.jpg
https://uploads.tapatalk-cdn.com/20200926/83d38d0ea27d2291addaf22e9cf642ef.jpg
https://uploads.tapatalk-cdn.com/20200926/3e3d401f5f044f3312829651e0639dc6.jpg
https://uploads.tapatalk-cdn.com/20200926/44af06eccea2821b2ea53b102b4c5c91.jpg
https://uploads.tapatalk-cdn.com/20200926/46d39b69511bc418553ae45c8738aaad.jpg


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[cjnuk3]

From the photos of the pcb it looks like this is a zener diode. I assume there are no numbers printed on it which would give you the voltage rating? Something like 6v8 etc. It's hard to see from your photos but if it has coloured bands on it that can also indicate the voltage though not all manufacturers follow the same pattern! Without a circuit diagram you're a bit stuck......

How do you know it's actually faulty?

[andyrlb]

From the photos of the pcb it looks like this is a zener diode. I assume there are no numbers printed on it which would give you the voltage rating? Something like 6v8 etc. It's hard to see from your photos but if it has coloured bands on it that can also indicate the voltage though not all manufacturers follow the same pattern! Without a circuit diagram you're a bit stuck......

How do you know it's actually faulty?

I can’t see any markings on it , even with a magnifying light and it’s hard to identify any strips .
It comes from a Denon CD player and when I googled “ dim display “ it appears to be a common fault and as the board is blackened around that diode I reckoned it must be that one causing the issue.
It’s only on a midrange midi system and it’s not a critical component for the cd operation , I just like my things to work 100%.


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[cjnuk3]

Have you got a multimeter?

[andyrlb]

Have you got a multimeter?

Yes I do .
Someone else suggested it’s a Zener diode of maybe 400mv or 500mv.


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[andyrlb]

I can see the markings are 248 or 24B


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[cjnuk3]

I've never heard of zeners with such a low breakdown voltage, you'd just use a normal diode if it was. They start at around 2.4v. If you can put the original back in circuit and measure the voltage across it that could help. Put it in the right way around obviously! You only need to tack solder it.

[cjnuk3]

Ah could be a 2.4 volt one, that would make sense.

[andyrlb]

Ah could be a 2.4 volt one, that would make sense.

Thanks, now with the aid of a jewellers magnifying light I can see it is clearly burnt


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[cjnuk3]

If you feel like splashing out 99p...

https://www.ebay.co.uk/itm/Zener-Diode-BZX55C-0-5W-Various-Values-5-10-or-20-Pack-UK-Seller/184235615704?hash=item2ae54c65d8:g:lpIAAOSwOjtfaIC h&redirect=mobile

[andyrlb]

If you feel like splashing out 99p...

https://www.ebay.co.uk/itm/Zener-Diode-BZX55C-0-5W-Various-Values-5-10-or-20-Pack-UK-Seller/184235615704?hash=item2ae54c65d8:g:lpIAAOSwOjtfaIC h&redirect=mobile

Ha ! At that cost why wouldn’t I at least try and fix it .

Thanks again


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[cjnuk3]

2.4v obviously. Even if it isn't the correct value the worst that will happen is that it will go pop and you've wasted 99p!

[cjnuk3]

If you could measure the voltage across where the diode would go before you order the replacement, just in case it might be a 24v one. I doubt it, you could always order 5 of each and get a whopping 2p discount....

[andyrlb]

If you could measure the voltage across where the diode would go before you order the replacement, just in case it might be a 24v one. I doubt it, you could always order 5 of each and get a whopping 2p discount....

Some else said 24v , I’ll order both and try the 24v first , they also said that if it is the diode then the display wouldn’t work at all , I’m thinking the diode is definitely burnt ( I can see the burns on the wires ) .


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[cjnuk3]

I would suggest trying the 2.4v first, squirting 24v around might cause damage to other components if it's not correct. You only need to put the wires through the holes and twist them so they make contact and quickly flick on the power. If nothing happens then maybe try the 24v but be ready to switch off quickly if you smell anything!

[andyrlb]

I would suggest trying the 2.4v first, squirting 24v around might cause damage to other components if it's not correct. You only need to put the wires through the holes and twist them so they make contact and quickly flick on the power. If nothing happens then maybe try the 24v but be ready to switch off quickly if you smell anything!

Ok I’ll do that , cheers.


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[cjnuk3]

Good luck!