Watch winder (Excelvan) not working

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Hi all, first of all, this is my first post, if in the wrong place, I'm sorry.

I have an excelvan watch winder which does not work. I will show pictures of the circuit board, I have changed the capacitor but to no avail.

I have tested the board with a multimeter and there appears to be 12 volts on the board but I cannot get the motor to kick in.

Would anyone know where I am meant to test to try to find the fault please?

I am not an electronics expert by any means, just like tinkering. But if someone could explane in really simple terms what can go wrong with this setup and what i could possibly do to fix.

I have tested the motor straight 12v and works ok? IMG_20210205_191353.jpg
 

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shortbus

Joined Sep 30, 2009
8,558
Just a guess. Have you checked continuity in the wires going from the board to the motor? If this works like I'm thinking it does, the motor wires moving back and forth could work harden and break internally. Why did you replace a capacitor?
 

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Just a guess. Have you checked continuity in the wires going from the board to the motor? If this works like I'm thinking it does, the motor wires moving back and forth could work harden and break internally. Why did you replace a capacitor?
Hi thanks for the reply.

At what point on the board and what point on the motor? Not too sure, I have tried the 2 wires coming from the motor direct to 12v and motor works?

I changed the capacitor because i thoughttat on this small board it has to be the only thing that can go wrong (I was evidently wrong)
 

JohnInTX

Joined Jun 26, 2012
4,434
Welcome to AAC!

Carefully inspect the soldering on the surface mount parts, the IC and the 3 pin transistors. Tiny hairline gaps can show up if the board wasn't properly soldered. I note this because over the holidays I rescued a set of fairy lights, a talking cat and a Lionel Polar Express train remote control. All had hairline fractures in the soldering of the processor. In fairness, while the cat and lights were manufacturing issues, the train was a victim of the dreaded TFE (Toddler Fury Effect). But in all cases, a touch up with a fine tipped soldering iron got things right again.

Also inspect the soldering on the connector header pins for the same issue. My money's on one of those..

If you can do it safely without contacting any conductors, sometimes you can find issues by pressing down on the SMT parts with the eraser tip of a pencil some other non-conductive thing to see what that does.

Good luck!
 

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Welcome to AAC!

Carefully inspect the soldering on the surface mount parts, the IC and the 3 pin transistors. Tiny hairline gaps can show up if the board wasn't properly soldered. I note this because over the holidays I rescued a set of fairy lights, a talking cat and a Lionel Polar Express train remote control. All had hairline fractures in the soldering of the processor. In fairness, while the cat and lights were manufacturing issues, the train was a victim of the dreaded TFE (Toddler Fury Effect). But in all cases, a touch up with a fine tipped soldering iron got things right again.

Also inspect the soldering on the connector header pins for the same issue. My money's one one of those..

Good luck!
Thank you for your reply.

No I have not looked closely at the joints but now you mention it, I will, just wondering if there can be voltages at most parts of the board if there are fractures within the joints?
Thanks.
 

JohnInTX

Joined Jun 26, 2012
4,434
just wondering if there can be voltages at most parts of the board if there are fractures within the joints?
Sure there can. I'm guessing that the 14-pin IC is a microcontroller which outputs control signals according to its winding schedule etc. If the 'run' signal doesn't get to the transistors that drive the motor for example, (it looks like an H bridge to drive the motor is both directions) you'll get voltage on lots of pins, just not the control signals you need for proper operation.

Are there any legible markings on the big IC?
 

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Sure there can. I'm guessing that the 14-pin IC is a microcontroller which outputs control signals according to its winding schedule etc. If the 'run' signal doesn't get to the transistors that drive the motor for example, (it looks like an H bridge to drive the motor is both directions) you'll get voltage on lots of pins, just not the control signals you need for proper operation.

Are there any legible markings on the big IC?
Thanks again for the info.

You are spot on with what you are saying, yes it is a micro controller as you set a control knob to set in both directions (I think there is 4 or 5 settings on it)

But I will look at these tomorrow and report back with any findings.

Thank you all for replys. Much appreciated.

Regards rob.
 

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Thanks again for the info.

You are spot on with what you are saying, yes it is a micro controller as you set a control knob to set in both directions (I think there is 4 or 5 settings on it)

But I will look at these tomorrow and report back with any findings.

Thank you all for replys. Much appreciated.

Regards rob.
Just a quick one, am I right in thinking these are a type of fuse? Screenshot_20210205_232538.jpg
 

JohnInTX

Joined Jun 26, 2012
4,434
Actually, that uC looks like it's toast. Those big divots on the top of the package look like heat damage from a popped chip.
Hoping it's not but..
 

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Actually, that uC looks like it's toast. Those big divots on the top of the package look like heat damage from a popped chip.
Hoping it's not but..
Hi m8 just had it under microscope and what is your honest opinion?

If worst case would you know how these chips are identified?
Thanks again.
 

JohnInTX

Joined Jun 26, 2012
4,434
Zoomed in, it just looks like scratches/scuffs on the chip. No bulged, cracked plastic from overheating internally. That’s good! No ID marks though. The bottom row of legs of the IC don’t look like they are fully down on the pads - check for cracks there?

Any markings on the 3 pin transistors?

Circled component in #5 looks like a ceramic capacitor to me. But it could be a fuse. Trace the connections if you can. A cap frequently will be across the traces. A fuse will be in series with thick, current carrying traces.

Google up some diagrams of an H-Bridge motor driver and see if those 3 pin SOTs fit that idea for a motor driver. If so, you can trace the 4 drive signals back to the uC and see if you’re getting drive to those to turn the motor on.

Nice pic BTW.
 
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Thread Starter

Rob-b30

Joined Feb 4, 2021
20
Zoomed in, it just looks like scratches/scuffs on the chip. No bulged, cracked plastic from overheating internally. That’s good! No ID marks though. The bottom row of legs of the IC don’t look like they are fully down on the pads - check for cracks there?

Any markings on the 3 pin transistors?

Circled component in #5 looks like a ceramic capacitor to me. But it could be a fuse. Trace the connections if you can. A cap frequently will be across the traces. A fuse will be in series with thick, current carrying traces.

Google up some diagrams of an H-Bridge motor driver and see if those 3 pin SOTs fit that idea for a motor driver. If so, you can trace the 4 drive signals back to the uC and see if you’re getting drive to those to turn the motor on.

Nice pic BTW.
Thanks for the pic comment.

I have looked over all of the board, everything looks solid on the controller there appears to be no cracks on any solder joints, can there be much more that can go wrong with these?
 

JohnInTX

Joined Jun 26, 2012
4,434
What kind of power supply is it?
Do you have power on the board?
If it is a direct to mains capacitor coupled low cost affair, the caps frequently lose value and don’t supply enough current. Be careful with these as you are not isolated from the mains.
 

Thread Starter

Rob-b30

Joined Feb 4, 2021
20
T
What kind of power supply is it?
Do you have power on the board?
If it is a direct to mains capacitor coupled low cost affair, the caps frequently lose value and don’t supply enough current. Be careful with these as you are not isolated from the mains.
There is a 12v multi voltage power supply which is at the back of the machine then a on off switch, then wires going to circuit board, then wires branching off circuit board to seperate battery compartment (already put batterys in without any power connected and still same result, not working) then wires to a round dial which I would imagine is connected on the pcb via the micro controller chip?
I would really like to achive a goal on this one and know what te problem might be.
 
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