Weigh scales indicator not turning on

Thread Starter

John JJ

Joined Aug 15, 2019
17
Hello guys
I have an industrial weigh scale indicator that was dropped from a height. When I opened it up the pcb was not fixed in place. The screws that hold the pcb were all sheared off. When I put power to it, it won’t turn on. I have inspected the board and it all looks good and all the solder joints look good. Any ideas what to check next would be much appreciated
Thanks
 

ericgibbs

Joined Jan 29, 2010
8,868
hi John,
It is common in that type of PCB to use the fixing/mounting screws as a 0V connection.
Did you check around the sheared holes for signs of copper tracking being disconnected.
Do you have a photo to post of the PCB.?
E
 

ericgibbs

Joined Jan 29, 2010
8,868
hi,
Nothing obvious on those shots.
Was it the Main PCB or Display PCB which has the sheared screws.

Did you check the back of the PCB's near the fixing screws for track damage also check that the DC power input is present and correct.

E
 

Thread Starter

John JJ

Joined Aug 15, 2019
17
The display side is where its sheared but is bolted in through from the main pcb and on the bottom two screws is a track leading to them. You could be right about the 0v connection. I will get new studs and fix it back in. Will keep you posted
Thanks
 

Thread Starter

John JJ

Joined Aug 15, 2019
17
Ok just an update. Got new studs fixed in place. Pcb mounted back in and now we are getting progress. Indicator now clicks on but doesn’t light up unless I press a component down a little bit. It seems loose. I have circled it on photo but there is silicone covering it. Do any of you guys know what this is?
 

Attachments

ericgibbs

Joined Jan 29, 2010
8,868
hi John,
Is the RED arrowed wire part of the encapsulated component,?
Is that point where the wire passes that pin touching the pin.? [ until you press down]
E
F700421C-555E-4A36-8463-A6E59607AB64.jpeg
 

Thread Starter

John JJ

Joined Aug 15, 2019
17
Hello
That is just a piece of thin rubber glue that you have arrowed. It’s not a wire. The component that I have circled is a bit loose. The plastic part of the component seems to be coming apart. Is it some sort of an inductor?
 

ericgibbs

Joined Jan 29, 2010
8,868
hi,
OK, Has does that ferrite core underneath the 'mystery' component have any turns of wire wrapped on on it.?
I suspect that the component is an inductor thats placed across that ferrite which intention of coupling with the ferrite.
That's why when you press down you are increasing the coupling.????

E


Update:
What is Makers Model type/number of the Unit, we may be able to get a circuit diagram online.
 
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Thread Starter

John JJ

Joined Aug 15, 2019
17
The component does have turns of wire on it. I will get back to you on a make, model of board when I get back home later
Thanks
 

jpanhalt

Joined Jan 18, 2008
8,080
Yes, and 101 means 100 uH is its inductance.

Moreover, the ferrite it is wound on is fragile like glass, so it's not surprising it broke too.
 

Thread Starter

John JJ

Joined Aug 15, 2019
17
Is it just a matter of finding one the same size? Mine is 10mm * 10mm * 3.5mm high and making sure the inductance is the same. When looking online there is so many different sizes
 

jpanhalt

Joined Jan 18, 2008
8,080
Pretty much yes. There are also current and resistance rating/specifications, but if you find something at a major distributor that matches in size and looks, it is probably OK. If you have a way to measure the wire diameter that would nail it down, but in my experience, that style of inductor is pretty standardized.
 
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