[TriEmbed] laptop fan motor control question

Brian triembed at undecidedgames.net
Tue Feb 2 17:24:49 CST 2021


I store my paste at room temperature.  I like to live dangerously!  (I 
also don't have room in my house for another refrigerator, regardless of 
size...)

That said, I recently bought some fresh paste...although my old stuff 
(and I mean old...several years of room-temp storage) still reflows, I 
was amazed by how many fewer bridge problems cropped up with the fresh 
stuff.  My workflow had been stencil, place, reflow, clean up several 
bridges on all four sides of TQFPs...with fresh paste, there was almost 
no cleanup to be done.

I still store at room temp, though. XD

As an aside, I've been thinking about switching to a low-temp 
tin-bismuth alloy, but I hear even the tiniest bit of lead will really 
attack and weaken that stuff, and I can't guarantee there aren't some 
atoms of lead still clinging to my iron..

-B

On 2/2/21 5:14 PM, Pete Soper via TriEmbed wrote:
> Thanks, guys. The connections were red for positive, blue for ground and 
> brown for what I assume is the PWM input. It spins up with 5V just fine 
> and I feel silly about the high resistance measurement. The fan cools a 
> pair of heat pipes from two IC sites side by side and the whole thing is 
> copper. The IC sites have faint markings but I can just make out "attach 
> Peltier devices here". After only eight years I may be able to store my 
> solder paste in something smaller than a dorm fridge. :-)
> 
> -Pete
> 
> On 2/2/21 2:34 PM, Brian via TriEmbed wrote:
>> On 2/2/21 1:15 PM, Pete Soper via TriEmbed wrote:
>>> The DC resistance between any two pins with any polarity is much 
>>> higher than I would have expected: thousands of ohms.
>>>
>>
>> Others have already mentioned:
>>  - It's probably a brushless motor
>>  - Three wires are probably power, ground, and tachometer
>>
>> The reason you see an unexpectedly high resistance across the power 
>> leads is because there are active electronics inside the thing to 
>> commutate the brushless motor.  You're not measuring a motor winding.
>>
>> I say if you have a red and black wire, hook that up to +5 VDC and see 
>> if she spins.
>>
>> -B
>>
>> _______________________________________________
>> Triangle, NC Embedded Computing mailing list
>>
>> To post message: TriEmbed at triembed.org
>> List info: 
>> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
>> TriEmbed web site: http://TriEmbed.org
>> To unsubscribe, click link and send a blank message: 
>> mailto:unsubscribe-TriEmbed at bitser.net?subject=unsubscribe
>>
> 
> _______________________________________________
> Triangle, NC Embedded Computing mailing list
> 
> To post message: TriEmbed at triembed.org
> List info: http://mail.triembed.org/mailman/listinfo/triembed_triembed.org
> TriEmbed web site: http://TriEmbed.org
> To unsubscribe, click link and send a blank message: 
> mailto:unsubscribe-TriEmbed at bitser.net?subject=unsubscribe
> 





More information about the TriEmbed mailing list