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Need help determining electronic component

Jeen

May 19, 2021
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Salutations, Electronicspoint Community.

This is my first time posting, so if I missed something, let me know.

I recently purchased a BTI LCD-386 Portable Computer, upon powering on, there is a buzzing sound. Just to be sure I was hearing a buzzing, I powered it on a couple more times, because, you know, that's a great idea.

Anyway, pretty sure I have found the culprit. In the pictures below, you will see a burned out component, and in the other picture, an intact component. I'm pretty new to electronic components, but I can tell a capacitor from a resistor, for the most part, so this burned out component is throwing me for a loop. There's actually two of these components burned out, and they're across the circuit board from one another. Same component though, same condition.

I could use some help determining what this thing is so I can get it replaced.The surrounding components I intend to replace as well, but I figured I would focus on this mystery component first.

Circuit board model number is "386wb4a3.b1", Google searching actually brought up a couple of hits, one of which appears to address this exact issue where they state "After poking around with my multimeter a couple of minuts I found a dead short at capacitor C11.", but never actually addresses what the capacitor type or rating is.

Any help with identifying the type, rating, and potential replacement would be greatly appreciated.
 

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Bluejets

Oct 5, 2014
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possible that bank could be all the same value....are they in parallel on the pcb side???
 

Harald Kapp

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possible that bank could be all the same value
rather likely.
I see 10 µF, 16 V tantalum capacitors.
Tantalum capacitors are know to be susceptible to being operated near their rated voltage. They easily burn. When you replace them, try to find 10 µF 25 V types for improved headroom. I also suggest that you replace the full row, just in case the others, seemingly good ones are not partially damaged and may fail soon.
 

Jeen

May 19, 2021
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rather likely.
I see 10 µF, 16 V tantalum capacitors.
Tantalum capacitors are know to be susceptible to being operated near their rated voltage. They easily burn. When you replace them, try to find 10 µF 25 V types for improved headroom. I also suggest that you replace the full row, just in case the others, seemingly good ones are not partially damaged and may fail soon.

So all components are on one side of the board, the opposite side of the board is just solder points.

Looking over the board, it appears that all of these capacitors bear the same "10+ 16r" markings. Tantalum capacitors were my original thought, but I could not figure out the "16r" in the "10+ 16r" marking. I'm still pretty new to this.

My intention is to start by replacing the burned out ones first, test it, then replace the rest on the board just to be safe. There are about 20-30 of these capacitors on the board.

I'll see if I can get my hands on some "10 µF 25 V" tantalums and see what happens.

There is another component I have not started identifying on my own yet, it's on the same board, part of the same problem. Do I need to open a new thread when the time comes or can I just update this thread with pictures and questions?

Also, thank you Harald and Bluejets for your help.

Edit* I'm looking now, and I believe it is some kind of inductor, but the left side of the "burned set" picture, there are some components denoted by their marking on the board by "L#". The numbers on the circuits themselves are "271", however, the "1" looks like a lowercase "L", so I don't know if it is a "1" or "L" or uppercase "i". I can include a close up picture if requested.
 
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Jeen

May 19, 2021
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Here is an up close shot of the "271". The back side is blank.The shot does not show it, but it has 3 legs.

The closest looking component I could find was a Ceramic Resonator. The only location these components exist are right here in this picture, in the corner of the circuit board. The white plug you see in the "Burned Set" picture, that is the adapter where the PSU plugs into the circuit board, so these "271" components are in line or at least really close in proximity to where power is coming in.
 

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Martaine2005

May 12, 2015
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L reference designator is an inductor.
271 is likely 270μH.
But I have to admit, I have not seen those before. Could they be dual mode chokes? Or just common mode in a different package?.

Martin
 

Jeen

May 19, 2021
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L reference designator is an inductor.
271 is likely 270μH.
But I have to admit, I have not seen those before. Could they be dual mode chokes? Or just common mode in a different package?.

Martin

I don't know anything about that, and I mean that literally. I will do some research to get caught up on what chokes are.

The circuit board indicates it was manufactured in Taiwan, but no manufacture date.

I found another auction for this same model and they indicate the model year is 1988, however, I cannot say whether this is true or not.
https://www.worthpoint.com/worthopedia/vintage-1988-solution-microcomputer-1816830973

I mention the date and location of manufacture in case that could help pin point what these "271" component are.
 

Martaine2005

May 12, 2015
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An inductor is a coil and so is a choke. A choke can have opposing coils.
So can have the same ref des.

Martin
 

73's de Edd

Aug 21, 2015
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That is a round 270 uh choke that goes up one side and then another one that goes down the other side.
Their midpoint connection also has a 0.1 ufd ceramic bypass capacitor which then goes down to their central ground connection.
Probably zero electrical defects on the frontal 3 . . . . just having a mild sooty coating, which should clean off.
Pic clarity won't let me fully evaluate the one in the foreground . . . . you test and call it.
 

Jeen

May 19, 2021
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So I pulled off the most charred looking "271" and "Disassembled" it. What appeared on the two cylindrical sides were what appear to be a magnetic material. Somewhat magnetic anyway, kind of stuck to the blade of the knife used to take the "271" apart. Looking over what Bertus was saying about it being a EMIFIL, I was able to find the following:

https://www.murata.com/en-us/products/emc/emifil/overview/lineup/lead

The "271" looks just like the Disc Type EMIFIL, I'm thinking Bertus was right on the money with this one.
 

73's de Edd

Aug 21, 2015
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Yep . . . .exactly as described above . . . with a powdered iron core or ferrite used according to RF spectrum coverage needed.
Now are the end to end inductors low resistances in agreement with the like companions above ?
 

Jeen

May 19, 2021
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Yep . . . .exactly as described above . . . with a powdered iron core or ferrite used according to RF spectrum coverage needed.
Now are the end to end inductors low resistances in agreement with the like companions above ?

I'm afraid you lost me with your question. I'm very new to electronic components and terminology.
 

Jeen

May 19, 2021
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So after a long hiatus, I have the capacitors, and I am slowly making my way through getting the old ones replaced on the board. In between, I'm looking at how to determine what rating EMI Filter I need to order from the link above. So far, all I have determined is that I need a 100v. Beyond that, everything is gibberish.

Does anyone have any tips on how I can determine what kind of EMI filter I already have? I managed to salvage a couple of intact filters from the board and I have a voltmeter at my disposal. Otherwise, It's back to looking at gibberish.
 
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