Debugging Circuit Board?

Thread Starter

Arash Nikkar

Joined Feb 1, 2018
4
Hi,

We recently bought a house that has an old set of motorized window blinds. One of the blinds is unfortunately dead, and the manufacturer no longer makes a replacement (they are from 2003).

I took everything apart and did my best to diagnose it and found that the motor itself actually works (when I connect power to it). Which means that somewhere something is breaking on the circuit board.

Is this something I can debug and attempt to fix, or am I completely out of luck.

Thanks! (and apologies if this is the wrong forum to post in).
 

AlbertHall

Joined Jun 4, 2014
12,338
Just trace all of the relevant connections in the control circuit and make a schematic from them.
This generally is quite difficult if you haven't done it before.

Could you post some good close photos of both sides of the board and maybe we can work out something from that.
 

Thread Starter

Arash Nikkar

Joined Feb 1, 2018
4
This is the best picture I have now, but I can take another one.

I've verified that the power coming in is good, but when I depress the button on the side, I nothing happens. I'm realizing now that I guess I could take another one apart and try and trace the voltage patterns upon the button depress. But even then, I wouldn't know what to replace or if I even have the skill level to do so.
 

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dl324

Joined Mar 30, 2015
16,788
Cropped to the relevant portion:
upload_2018-2-1_11-32-15.png
Are you able to remove and replace surface mount devices? If not, there's no point in proceeding.
 

ian field

Joined Oct 27, 2012
6,536
Any guidance on how to do that? I'm comfortable with electronics...just need to be pointed in the right direction :)
Through hole components on single sided board is fairly easy - SMD and multiple layers makes hand tracing tortuous at least.

Most capacitor ESR meters ignore semiconductor junctions and can resolve sub-Ohm resistances, so you can identify where tracks end up - but its seriously hard work.
 

Thread Starter

Arash Nikkar

Joined Feb 1, 2018
4
but its seriously hard work.
Yea, I'm worried I'm barking up the wrong tree. I have no idea what I'm doing :)

On the flipside, it's already broken, so I can't really break it more.

I'll have to take a closer look this weekend to really decide if I can remove/replace the surface mounted pieces successfully.
 

ian field

Joined Oct 27, 2012
6,536
Yea, I'm worried I'm barking up the wrong tree. I have no idea what I'm doing :)

On the flipside, it's already broken, so I can't really break it more.

.
You might just happen to spot what's wrong as you handle and examine the board - it could be worth not adding to the damage if you can help it.

Check for dodgy soldering first, then move on to any electrolytics.
 
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