Strange looking diodes

[throbscottle]

I recently recovered some odd looking diodes from the psu sections of a couple of scrap monitor pcb's, pretty sure they're not zeners, I think they might be Schottky diodes or high speed rectifiers - but any suggestions, anybody?

Both diodes have a forward voltage of just over 0.5V, are small short bodied, same length as diameter, plastic package - probably half the length and slightly fatter than a 1n4001, hence "strange looking". One has a purple cathode band and is marked 4E, the other has a broken (like teeth on a gear) white cathode band, and is marked 06 24 with the 06 oriented around the body and the 24 oriented along the body.

If anyone could suggest what these might be, I'd be happy.

Thanks in advance.

 

[atferrari]

Save 1000 words (or more...)

Pictures can be, decorative, artistic or illustrative.

These people did mostly the first two.

Try the last category. It works.

 

[Ian Rogers]

A TVS ( Transient Voltage Suppressor ) looks similar to a diode... Sounds very much like your description.

 

[MrAl]

Hi,

I'd like to see several high resolution photos from several spherical 3d angles. The more the better.
With no part number or schematic it's very hard to match up. Alternately the circuit can be traced by hand by taking photos or scans of front and back, then tracing each copper trace. I've done this several times and it works pretty well unless the board has several layers. With one or two layers it does work however. Top photos from several angles helps too sometimes to see around or under parts.

 

[throbscottle]

I only have a little compact camera and big magnifying glass - this was the best I could do. Biro is for scale. 1000 words might be more help in this case! The boards they came from are long gone so no chance of tracing a schematic from them. TVS explanation seems likely though. Never heard of those until today.

View attachment 63376

 

[MrAl]

Hi,


How did you know they were diodes in the first place? Could one of them be something else?

 

[throbscottle]

They look like diodes, albeit unusual ones, and only pass current one way, so it's a safe assumption they're some kind of diode, and probably a special kind since there were dozens of ordinary signal diodes and rectifiers on the same pcb's. I'm going with Ian Roger's TVS theory at the moment unless someone has a better suggestion. Fascinating.

 

[unclejed613]

they're high speed diodes most likely. Samsung, Sony, LG and a lot of others use these diodes in SMPS circuits. they're probably not as fast as schottky diodes, but anything less than 250nS recovery time is considered fast. i used to do a lot of computer monitor repair, and i used to replace all of these with a single diode type that had a recovery time of 35nS. i think they were MUR115's if it was on the low voltage side that i used. if the switching frequency is high enough, a diode generates extra heat during it's recovery time because it's in reverse conduction for a short time. a faster diode runs cooler in a SMPS.

 

[throbscottle]

Does that fit with just finding one per psu then? I don't know much about smpsu's! At least it's one of the things I thought of!

Many thanks for all the replies

 

[unclejed613]

many SMPSs in consumer electronics (like blu-ray players, DVD players, etc...) have a few outputs, usually +3.3V@ about 3-5A, 5V@2-5A, 12V@1A (and it may have two, one +12V, the other -12V), and if it has a fluorescent display, -30V@100mA. the diodes you are asking about are 1A diodes, and so came from either the 12V supply or the FD supply. TVs often have several supplies, and you might find 3 or 4 of those diodes in a TV power supply.

 

[MrAl]

They look like diodes, albeit unusual ones, and only pass current one way, so it's a safe assumption they're some kind of diode, and probably a special kind since there were dozens of ordinary signal diodes and rectifiers on the same pcb's. I'm going with Ian Roger's TVS theory at the moment unless someone has a better suggestion. Fascinating.

Hi,

Oh ok, so they must be diodes then. Nice pic too BTW, it's funny how much a magnifying glass can help with quick macro photography. I've used the same to photograph small electronic parts in the past with SLR cameras and digital too, and got some nice close ups. I highly recommend others trying this too because all you have to do is hold the magnifying glass in front of the camera lens.