Author Topic: What is this item found on a PCB?  (Read 4476 times)

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Offline upl8Topic starter

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What is this item found on a PCB?
« on: April 14, 2019, 07:36:09 am »
Found this attached to the PCB of a Tivo. It has small holes in the middle of the case and loose balls inside. It was face-down with only the white paper backing showing from above. The only identifier on it is W09.
 

Offline Psi

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Re: What is this item found on a PCB?
« Reply #1 on: April 14, 2019, 08:04:38 am »
My guess is moisture absorber/ desiccate.
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Online rstofer

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Re: What is this item found on a PCB?
« Reply #2 on: April 14, 2019, 08:21:13 am »
Maybe it provides weight.
 

Online ataradov

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Re: What is this item found on a PCB?
« Reply #3 on: April 14, 2019, 08:23:11 am »
Weight was my first guess, but TiVO is a set top box like thing. I doubt it needs any additional weight.

But if this was on the remote, for example, then it is probably a dummy weight to make it feel more balanced.
« Last Edit: April 14, 2019, 08:37:19 am by ataradov »
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Offline upl8Topic starter

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Re: What is this item found on a PCB?
« Reply #4 on: April 14, 2019, 08:35:30 am »
It only weighs 1.5 grams. As ataradov said, the Tivo is like a set top box. It has a 3.5" hard disk in it, so no need for an extra 1.5 grams. The balls inside aren't attracted to a magnet, but they easily pick up a static charge.
 

Offline sleemanj

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Re: What is this item found on a PCB?
« Reply #5 on: April 14, 2019, 10:25:35 am »
My guess is a spill detector, maybe changes colour or something when the balls get wet.
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Offline Psi

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Re: What is this item found on a PCB?
« Reply #6 on: April 14, 2019, 10:27:35 am »
can we see more photos front different angles and also see a shot of it on the pcb?
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Offline upl8Topic starter

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Re: What is this item found on a PCB?
« Reply #7 on: April 14, 2019, 11:24:02 am »
My guess is a spill detector, maybe changes colour or something when the balls get wet.

I poured some water over it. The face that was visible when it was attached shows some black now, but I'm not sure it's permanent.


can we see more photos front different angles and also see a shot of it on the pcb?

Some more photos attached. Unfortunately the PCB is gone. My Dad pulled it apart and asked me if I knew what it was. The "Top" photo is what you would see when looking at the PCB. The holes were facing down towards the PCB. The "Size" photo shows the residue from the glue that was holding it to the board. The five small holes are in the circle in the middle.
 

Offline Psi

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Re: What is this item found on a PCB?
« Reply #8 on: April 14, 2019, 12:09:14 pm »
It also reminds me of insect bait/poison.
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Offline upl8Topic starter

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Re: What is this item found on a PCB?
« Reply #9 on: April 15, 2019, 10:56:57 am »
The top turned white again after it dried, so not a spill detector.
 

Online iMo

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Re: What is this item found on a PCB?
« Reply #10 on: April 15, 2019, 11:34:40 am »
Looks like activated charcoal (carbon) in form of balls.
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Offline CJay

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Re: What is this item found on a PCB?
« Reply #11 on: April 15, 2019, 12:30:26 pm »
Ah, all these educated people and none have realised it's an implementation of the CD-ROM CAV disc balancing system referenced in the patent link below for PCB balancing to ensure level flight and accurate aim in repair shops in the even of the board being designated Failed Under Continuous Test

https://patents.google.com/patent/US6061325A/en
 
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Online mikeselectricstuff

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Re: What is this item found on a PCB?
« Reply #12 on: April 15, 2019, 12:38:30 pm »
Seems to have some PCB-trace like patterns on the surface - were there PCB tracks under it?
If so it could maybe some kind of humidity or maybe motion /shock sensor. Are the balls conductive?
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Offline Bud

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Re: What is this item found on a PCB?
« Reply #13 on: April 15, 2019, 01:26:56 pm »
Why would a goddamn tv streaming box would need a humidity or motion sensor.
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Online mikeselectricstuff

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Re: What is this item found on a PCB?
« Reply #14 on: April 15, 2019, 01:39:49 pm »
Why would a goddamn tv streaming box would need a humidity or motion sensor.
Hard disk warranty claims
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Offline Psi

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Re: What is this item found on a PCB?
« Reply #15 on: April 15, 2019, 01:44:58 pm »
It couples to 3 capacitive touch pads on the pcb and provides a random number seed.
Effected by the position/stackup of those black spheres as well as humidity.
« Last Edit: April 15, 2019, 01:46:42 pm by Psi »
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Online mikeselectricstuff

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Re: What is this item found on a PCB?
« Reply #16 on: April 15, 2019, 02:08:17 pm »
It couples to 3 capacitive touch pads on the pcb and provides a random number seed.
Effected by the position/stackup of those black spheres as well as humidity.
Why would they not use timing of user remote buttons and/or network activity for random seeding ?
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Offline Psi

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Re: What is this item found on a PCB?
« Reply #17 on: April 15, 2019, 11:07:36 pm »
It couples to 3 capacitive touch pads on the pcb and provides a random number seed.
Effected by the position/stackup of those black spheres as well as humidity.
Why would they not use timing of user remote buttons and/or network activity for random seeding ?

dunno, i'm just trying to think up as many ideas as i can.
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Offline Brumby

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Re: What is this item found on a PCB?
« Reply #18 on: April 15, 2019, 11:13:45 pm »
Why would a goddamn tv streaming box would need a humidity or motion sensor.
Hard disk warranty claims

... or spilled beer detector?
 

Offline Psi

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Re: What is this item found on a PCB?
« Reply #19 on: April 16, 2019, 12:05:11 am »
It looks the same as this thing from inside a HDD, just a different plastic package

https://youtu.be/5pP2tcsCnrk?t=85


I stand by my first guess
« Last Edit: April 16, 2019, 11:42:45 am by Psi »
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Offline xavier60

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Re: What is this item found on a PCB?
« Reply #20 on: April 16, 2019, 02:37:36 am »
spherical activated carbon beads from this manufacturer can be 0.7mm average diameter, http://www.kureha.com/pdfs/Kureha-BAC-Bead-Activated-Carbon.pdf
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Offline windsmurf

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Re: What is this item found on a PCB?
« Reply #21 on: April 16, 2019, 03:34:10 am »
So that must have come out of the hard drive in the Tivo?
 

Offline upl8Topic starter

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Re: What is this item found on a PCB?
« Reply #22 on: April 16, 2019, 10:10:42 am »
Seems to have some PCB-trace like patterns on the surface - were there PCB tracks under it?
If so it could maybe some kind of humidity or maybe motion /shock sensor. Are the balls conductive?

He doesn't remember seeing any tracks under it. I don't think the balls are conductive, they stick to the side of the case if you shake it (static).


It looks the same as thing thing from inside a HDD, just a different plastic package
https://youtu.be/5pP2tcsCnrk?t=85
I stand by my first guess

Yes, I think your are right. Even the texture of the balls looks the same under magnification.


spherical activated carbon beads from this manufacturer can be 0.7mm average diameter, http://www.kureha.com/pdfs/Kureha-BAC-Bead-Activated-Carbon.pdf

Size looks about right.


So that must have come out of the hard drive in the Tivo?

I asked him today. Not from inside the drive, but it was attached to the PCB on the drive. I didn't know this until today.

So it looks like this might be a desiccant and/or filter attached by the HDD manufacturer. Found an image that looks very similar.

Thanks all for your suggestions, I think the mystery is solved.


 

Online mikeselectricstuff

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Re: What is this item found on a PCB?
« Reply #23 on: April 16, 2019, 11:25:15 am »

He doesn't remember seeing any tracks under it. I don't think the balls are conductive, they stick to the side of the case if you shake it (static).

they would stick regardless of conductivity
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Offline upl8Topic starter

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Re: What is this item found on a PCB?
« Reply #24 on: April 16, 2019, 03:27:05 pm »
they would stick regardless of conductivity
Is that because the balls are contained in an insulating case?
 


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