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Can anyone identify this component for me please.

Sparkymark

Feb 16, 2024
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Hi, I am in the middle of diagnosing another PSU. Xbox one power brick to be specific. I have found a component marked as BC801. It measures shorted thru so not sure if a shorted cap as caps usually brown in colour and this is black. I am baffled as to what it is and nothing on the Web. Any help appreciated. The component in question is on the far left. I have included as much of the nearby components as possible to help.
Thanks
 

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kellys_eye

Jun 25, 2010
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I have found a component marked as BC801.
No you haven't - you've found a DESIGNATION of 'BC801' - the component itself is unmarked. As much as it looks like a resistor it could be a small inductor given the 'short' reading. Since that board has components on the other side we would need to see them (and the related position of BC801 in respect to the topside parts) to get an idea of what it is.

Can you find a schematic?

Have you checked out Youtube for advice?

 

Martaine2005

May 12, 2015
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As above, unfortunately it’s just a reference designator.
Usually C, R, FB, D, X, TR etc.
BC, I have no idea. Again, unfortunately, SMD components don’t have the usual obvious clues to what the components are.
Sometimes, they are deliberately labelled in house to avoid copying.
But an overview of the board on both sides may give an idea.
 

Sparkymark

Feb 16, 2024
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No you haven't - you've found a DESIGNATION of 'BC801'
Sorry, yes that's what I meant, just my terminology is not the best. I understand 'C' is usually capacitor 'R' resistor and so on but this one is 'BC' and shorted thru. B would normally be buzzer from what I've found and C capacitor so just bemused as to what it is. As Martaine said it could be marked in house to avoid copying.
 

Sparkymark

Feb 16, 2024
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That YouTube video is useless, I've changed all the caps. I have fluctuating voltage causing it to shut down when it detects under undervoltage. Been trying to find what's causing the voltage to fluctuate.
 

H2814D

Nov 4, 2017
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Hi, I am in the middle of diagnosing another PSU. Xbox one power brick to be specific. I have found a component marked as BC801. It measures shorted thru so not sure if a shorted cap as caps usually brown in colour and this is black. I am baffled as to what it is and nothing on the Web. Any help appreciated. The component in question is on the far left. I have included as much of the nearby components as possible to help.
Thanks
Have you tried taking it off of the board and testing it with the various multimeter settings? It might not really be "shorted thru" as you call it.
 

Sparkymark

Feb 16, 2024
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Have you tried taking it off of the board and testing it with the various multimeter settings? It might not really be "shorted thru" as you call it.
No not yet, just been probing around to see if anything unusual. I do have fluctuating voltage which is causing one of the chips to shut down the PSU. Seem to start at a small transformer as I'm getting 345v on one side of the winding and it's bouncing all over on the other side of the winding. Anything from 0v all the way up to 400v and all sorts in between. Been trying to figure out what causing that.
 

Delta Prime

Jul 29, 2020
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I'm a 0.1%'er can you please take a photo of the other side of the board. thank you.
Just call me zero for "short" pun intended.
 

kellys_eye

Jun 25, 2010
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No not yet, just been probing around to see if anything unusual.
With all due respect (prelude to me saying something you're not going to like to hear....lol)

"Probing around" seems to be your go-to fault-finding method which, as experience will eventually teach, hardly ever leads to anything useful least of all valuable knowledge on 'what you're doing and WHY'.

I appreciate your enthusiasm and desire to move into the world of electronics but you'd be better served getting some background knowledge of simple, basic circuitry and how it operates before proceeding into repairs of SMPS devices. You are stumbling around n the dark and potentially causing more harm than good. This becomes even more problematic as the devices you're currently working on don't have schematics available for them.

There are 'primers' on the inner workings of SMPS devices that you should read and fully understand before going any further. Such documents would at least give you the ability to recognise the various parts (sections as well as components) of SMPS devices and armed with even that basic information you can proceed in a more methodical method.

One of the better ways to understand SMPS operation is to download the datasheets for the active devices (the main controller) as they often include basic schematics of operation as well as detailed descriptions of the inner workings of the devices themselves. All that info can be applied to any SMPS unit and improve your chances of a successful repair by leaps and bounds.
 

Sparkymark

Feb 16, 2024
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"Probing around" seems to be your go-to fault-finding method which, as experience will eventually teach, hardly ever leads to anything useful least of all valuable knowledge on 'what you're doing and WHY'.

I appreciate your enthusiasm and desire to move into the world of electronics but you'd be better served getting some background knowledge of simple, basic circuitry and how it operates before proceeding into repairs of SMPS devices. You are stumbling around n the dark and potentially causing more harm than good.

One of the better ways to understand SMPS operation is to download the datasheets for the active devices (the main controller) as they often include basic schematics of operation as well as detailed descriptions of the inner workings of the devices themselves.
Ok, your first point about that being my go to method, wrong. Ive been removing multiple components and testing as I know sometimes can give false readings in circuit. The probing helps to follow voltages and see where it goes wrong, possibly.

As for the learning basic circuitry, there is basic circuitry within the SMPS but also some quite complex circuitry. I'm really not bothered if I make it worse as long as I learn along the way as anything I am buying and working on is just a hobby and will just end up as donor parts if it doesn't get fixed.

I have been downloading datasheets, and looking at different components but when I come across things that I'm not too sure about I come on here.

I thought this forum was so people who have a bit or alot of knowledge could help people like me who have little knowledge but wanting more. It seems all you want to do is pull apart everything I say and push me away. Like posting me a video of some guy changing capacitors like that's gonna help.
 

Bluejets

Oct 5, 2014
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Electronics can be quite complex. Those in the know have probably spent the best part of their lives studying theories and principles. Then you come along and expect them to condense all that learning into a miniscule pocket which describes everything so you can understand.
If you want to learn as you say you do, do the long hard haul like others have had to do and don't expect the impossible just because you feel like it is "owed" to you.
 

Sparkymark

Feb 16, 2024
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Electronics can be quite complex. Those in the know have probably spent the best part of their lives studying theories and principles. Then you come along and expect them to condense all that learning into a miniscule pocket which describes everything so you can understand.
If you want to learn as you say you do, do the long hard haul like others have had to do and don't expect the impossible just because you feel like it is "owed" to you.
I know it's complex.
Those in the know have all the knowledge, exactly. Not expecting all that knowledge condensed into one lesson. Just giving information on what I find and using to the best of my very little knowledge to paint a picture so one of those in the know can possibly point me in a direction where to look for a particular fault.

How did you come to the conclusion that I feel it is owed to me? That's what the forums are for aren't they? Or am I wrong? Are the forums just for the experienced to put others down just because they know more. I am learning all the time and as you said there is alot to learn. I really don't want to come across as shirty but it's hard not to.

Just asking for advice is now considered entitled.
 

Sparkymark

Feb 16, 2024
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I'm a 0.1%'er can you please take a photo of the other side of the board. thank you.
Just call me zero for "short" pun intended.
Here is a photo of both sides. I'm sure it is an inductor
 

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kellys_eye

Jun 25, 2010
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Ok, your first point about that being my go to method, wrong. Ive been removing multiple components and testing as I know sometimes can give false readings in circuit. The probing helps to follow voltages and see where it goes wrong, possibly
There's no point in 'following voltages' if you don't know what those voltages are supposed to be.

I do have fluctuating voltage which is causing one of the chips to shut down the PSU.
What is it that makes you think the fluctuating voltage is causing a shut down? How do you know it's not meant to fluctuate? And what does 'fluctuate' mean - in this context - anyway?

The above are two examples that give me the impression that you're just 'probing around' and not understanding what you're doing and why. This will only confuse you, not give you the answers or knowledge you seek and lead us down a wrong path (potentially).

We WANT to help. We give advice freely and in our own spare time so there's no way your claim that the knowledge offered is 'entitled'.

If you look at the datasheet for the TNY276 you will see a pretty good example schematic like this:Screenshot from 2024-03-06 19-22-49.png

Which could assist in fault finding if you can associate those parts to what you have in front of you. The datasheet also shows a lot of waveforms but that implies you having a 'scope and the knowledge on how to use it.
So, using the schematic and the detailed description of how the chip works is a good starting point in how to interpret the circuit in front of you.
Start from the input, determine that the supply to the chopper is ok, disable the output (load) side and see if the chopper starts working again )seems as if it's shutting down due to an overload or fault condition through its enable input but you should be able to measure the voltages and compare the results with the description in the datasheet.
 
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Sparkymark

Feb 16, 2024
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Thank you, I was a incorrect on pins of that chip but I had a new DMM today and voltage sits steady 345 on both pins of the winding so something else must be causing it. The comment about being entitled was a response to the other guy saying I feel like I'm owed it and that's not the case at all. I come here and ask question in a way I understand what I am looking at and if I am corrected I will improve. Thats all I ask, I don't mind constructive criticism because that helps. I will take a look at the data sheet again for that chip. Thanks
 

Delta Prime

Jul 29, 2020
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You're okay kiddo!
A bully in wheelchair is still a bully! A DMM is just a tool, you need the proper tools for a complete diagnosis of the board. Believe me when I tell you once you've done it once,you'll never do it again. Your enthusiasm is refreshing don't ever lose that!
 

Sparkymark

Feb 16, 2024
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You're okay kiddo!
A bully in wheelchair is still a bully! A DMM is just a tool, you need the proper tools for a complete diagnosis of the board. Believe me when I tell you once you've done it once,you'll never do it again. Your enthusiasm is refreshing don't ever lose that!
It is a much better DMM tho so pleased with it. Gotta keep on going for my brain, my day job is not very taxing. Need stimulation.
 

Sparkymark

Feb 16, 2024
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I deleted this post as I put it in the wrong place.
 
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