sot23-5 LD7D0

Thread Starter

IMP002017

Joined Jan 28, 2017
192
Hello all I have looked and can't find. I am going to guess that the person that put these may have put their own # as I can't find it anywhere.. I have 2 that are burnt and hardly could make out the markings.

I am going to guess it is part of the POE input of the device

So it is 3 pins on one side and 2 on the other. Anyone work with this part # know what they are or what part I could replace them with?

Thanks
James
 

Thread Starter

IMP002017

Joined Jan 28, 2017
192
U35 and U37 The image is to large and for some reason I can't seem to find out how to import an image to the forum using another server as the host as I can on other systems so sadly that will have to work. That is a Picture of the board with the burnt sot23-5
 

Thread Starter

IMP002017

Joined Jan 28, 2017
192
Well an update lol.. I can't find out what it is. No one wants to tell... So I did find a place to order one however they won't say for sure that it is the right item lol.. Seeing it is listed with like 4 or 5 others. When I asked they said they were the same blah blah. However I asked they please confirm Vin and Vout and max amps because there are to many USA offerings from .30mA to like 800mA. However they didn't want to give any info other then it would work lol... Almost ready to just take off the IC and hook up a PSU strange thing is that I don't know if they are both needed for it to work or only one. I am going to guess both. I did hook power to the input and tested the one that is still living on board. iT was showing 5v and I know they were 5v but what I don't know is there is nothing I can find that would allow a 48v input from the POE... Another strange thing lol..

While I know that a Bridge Rectifier can be added to a Dc-Dc device as a Reverse protection however this one has 2 lol One on the top and one on the bottom infact right on top of each other...

Anyway I am thinking that I should just put power to both 5v chip outputs and see if the system boots up..

Sadly the unit is out of Warranty by like 2 years so there is no harm if I fry it... Also have another in White that isn't POE MB isn't the same even though model number is the same. I would think there would be a way to just disable POE and save on having to have more then one PCB and then being double sided and Surface mounted things take time but I guess the cost to omit was still more then Redesign... Anyway I don't like the Color of the White one as it reflects to much. So Worse comes to worse I will swap guts to turn working white one into a working black one... That is if I don't have to pull anything other then the MB and swap. If i have to change out motor and Mic then I will just keep white as it is lol... Getting lazy in my old age...
 

MisterBill2

Joined Jan 23, 2018
6,717
Have you measured the resistance between pins? All of the circuits for POE,(Power Over Ethernet) use a center tapped transformer at each end of a pair to separate the DC power from the signal. So that is one thing that you will need to check by tracing the connections. Then you can know if it may be a diode bridge or a transformer, There is a big difference.
 

Thread Starter

IMP002017

Joined Jan 28, 2017
192
Yes thank you that is the one I was talking about. I asked them they don't want to say anything other then it will work they are all the same I am not sure that is true but OK
 

MisterBill2

Joined Jan 23, 2018
6,717
OK, it appears that I have missed a whole lot here, as evidently others have communicated a lot with details that have not been visible to me. In addition the rest of us are in trouble because it seems that we have two skilled mind readers communicating with nothing appearing. Mostly, power over Ethernet requires center tapped transformers and then diodes, and those are the parts that may burn up sometimes. It would be interesting to know what they are actually talking about.
 

Thread Starter

IMP002017

Joined Jan 28, 2017
192
No you didn't miss anything unless you are talking about the first 2 posts here. Second one shows picture of the SOT23-5 in hand.

Well if you are asking what I am talking about. There is a LInk in the second post to the Picture of the Parts in question... About the POE info I haven't messed with much with POE and other things that I own are built with quality parts that are from National, or TI, or other things that I can find a replacement for... Sorry about other things I noticed after the fact I guess it was just looking for the Info... Thank you as I have little more understanding about Poe devices that I didn't know before as I didn't take time to dive more into them...

So I wasn't sure how things worked in this device... I know it has 3 of the same chips. 2 are bad. After looking over the MB more I found that one of the Chips is For Audio only as the Audio driver Data sheet says it should have its own Power.
 
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