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  #1  
Old Thu 21 February 2008, 13:00
cncb
Just call me: Brian
 
Connecticut
United States of America
Problems with cooling fan.. - impeller touched the mounting plate

. . . . . .The "on" button turned on the magnetic relay (it clicked!) and the lamp is illuminated. Power to the PMDX board is hot, as it is apparent through the green led(s). However my geckos and heatsink fan under them are not. My wires on my fans aren't marked or colored so it was a 50/50 shot at which would be? Maybe doesn't matter polarity wise. Will try switching those now. . . . .
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  #2  
Old Thu 21 February 2008, 13:55
cncb
Just call me: Brian
 
Connecticut
United States of America
. . . . . Only thing now that doesn't work is the cooling fan. I've tried reversing wires to see if it's a polarity issue but it doesn't seem it is. It's a 115VAC - 60hz radioshack muffin fan. (32CFM - 130mA)

Rated current is 130mA @ rated voltage
Rated power is 10W max @ rated voltage

Suppose I'm either feeding too much power to it or it's not the correct fan for the situation.
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  #3  
Old Thu 21 February 2008, 15:02
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
Send a message via Skype™ to Marc Shlaes
Or it just flat doesn't work. Did you test it separately?
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  #4  
Old Thu 21 February 2008, 16:09
cncb
Just call me: Brian
 
Connecticut
United States of America
Nope, I was ignorant not to but new out of the box If igured there shouldn't be any issues. This will be one component a real pain to remove and test or replace, will require unbolting the gecko heatsink but if I need to I will. Cooling these is my goal especially since I plan on working them hard. Was thinking about it and possibly it's the power I'm feeding it. I figured since it's a 115vac power fan that I should feed it from the AC end, the power coming in. Should I try to feed it from dinnectors on the DC end? Lastly I do a hear a faint humming noise coming from the enclosure inside, its very faint. Would you guys suspect this is electricity in the trans/psu or possibly coming from a mis powered fan?

Gotta love how the simplest component in the whole box is the one that is giving me the hardest time!
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  #5  
Old Thu 21 February 2008, 21:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
. . . . .

The fan is connected to the right place, and the faint noise might be coming from it. (Your toroid transformer might also be making the noise - I don't know how good your ears are). While you have power to the fan, flick the impeller with your finger to see if you can kick it into life. Otherwise it sounds like a dud fan. (It would be dud if you tried it on DC first)
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  #6  
Old Fri 22 February 2008, 06:31
cncb
Just call me: Brian
 
Connecticut
United States of America
. . . . . I will try to jump start the fan, will likely order one online today anyways.

Thanks again everyone! Sean thanks for taking the risk in me and answering all of my questions. As soon as the fans working I will hook it up to a motor and see if we can't get it to purr.
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  #7  
Old Sun 02 November 2008, 14:02
cncb
Just call me: Brian
 
Connecticut
United States of America
Problems with cooling fan..

In the past I had issues with my cooling fan; it was mounted under an aluminum platform that 4 gecko 203v's mounted to.




This is a very similar controller to many of yours although I doubt my quality of work is better it was my best effort. Anyhow I made the mistake of not testing the cooling fan until I had everything mounted on top of it; making taking it out a complete pain and a lot of time. I was desperate at the time to just use the controller so I bought another one and mounted it on top blowing cool air. It has worked OK but the one underneath is optimal and more desirable and I think it would be working better. My machine is down so I took the time to work on the controller again and take the controller apart and I noticed something. After I took the fan out I was curious to see if it worked and to my suprise it did; it wasn't broken. And when I exchanged the working new one in its place put it back together and fired it up, the new fan didn't work.

It's as if the fan only works if it is out in my hand or standing up right? It's just strange to me because in my hand it works in any orientation; but I'm wondering if there is something the way I have it mounted that is causing it not to work? Appreciate any help, thanks guys!
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  #8  
Old Sun 02 November 2008, 14:17
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
It's not clear from the photo what the area around the fan looks like, but there are two issues I'd try to check: First, is there room for sufficient airflow on both sides of the fan? Air flow resistance could easily stall it. Second, are there any sources of magnetism, or electro-magnetism that are "grabbing" the fan? Note that this could even be just a chunk of ferrous metal, if it's in exactly the wrong place for the fan.
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  #9  
Old Sun 02 November 2008, 14:23
cncb
Just call me: Brian
 
Connecticut
United States of America
That's exactly what I was thinking but I just don't know enough about it. The back plate is steel but it sits about 3/4" away from the gecko's/aluminum heatsink (underneath them in the center you can't see it) and there is a cutout in the back plate for air to circulate. First thing I tried to do was mimic the situation out of the box on the bench that was going on in there. No matter how much air flow I restricted it still didn't stall; yet in the box it does.
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  #10  
Old Sun 02 November 2008, 17:34
TonyBert
Just call me: Tony
 
Centreville VA
United States of America
Brian,

any way that the frame is being twisted when you mount it and the fan is binding up on the frame?
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  #11  
Old Sun 02 November 2008, 19:31
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
One more thought, although you've probably covered this. Presumably, you have the fan configured as an exhaust, since we wouldn't want to blow dusty air into the box. What is the inlet for replacement air into the box, or are you testing the vacuum capacity of a muffin fan?
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  #12  
Old Sun 02 November 2008, 22:17
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I think your hassle is either a "twist" (as Tony suggested) or the impeller physically touching the plate. Can you still spin the fan freely after it is screwed down? If you hold the fan in position (without screwing it down) does it work then?

Blocking off the airflow actually makes a fan run easier! Yeah, most don't believe it, but you have all experienced it. Listen to your vacuum cleaner when you block the hose - it speeds up. Reason is simple: when it moves air, it is doing work . . . when you stop it from moving air, it sits and "cavitates" but does no work. (This is also true of most centrifugal pumps. Not true of "positive displacement" blowers/pumps.)
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  #13  
Old Sun 02 November 2008, 22:20
cncb
Just call me: Brian
 
Connecticut
United States of America
no, the fan blows cool air onto the heatsink/aluminum fixture which houses the gecko drives.. It merely circulates air within the controller's enclosure. As I said I don't think it has to do with restricting it's airflow because I tried reproducing a restriction in airflow on the bench and it doesn't do much to stall it; runs time.
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  #14  
Old Sun 02 November 2008, 22:22
cncb
Just call me: Brian
 
Connecticut
United States of America
Quote:
Originally Posted by Gerald D View Post
I think your hassle is either a "twist" (as Tony suggested) or the impeller physically touching the plate. Can you still spin the fan freely after it is screwed down? If you hold the fan in position (without screwing it down) does it work then?

Blocking off the airflow actually makes a fan run easier! Yeah, most don't believe it, but you have all experienced it. Listen to your vacuum cleaner when you block the hose - it speeds up. Reason is simple: when it moves air, it is doing work . . . when you stop it from moving air, it sits and "cavitates" but does no work. (This is also true of most centrifugal pumps. Not true of "positive displacement" blowers/pumps.)
Thanks for the suggestion/explanation and to all replies thus far. Gerald I will investigate further tomorrow. Twist in the frame of the muffin fan doesn't sound right, this thing is a metal body really strong would take a lot to do that. I will check on it tomorrow per your suggestion. Thanks.
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  #15  
Old Mon 03 November 2008, 04:03
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Does it work when it is in the upright position and still touching the drive cabinet? Maybe a weird electrical short? just thinking out loud.
Sean
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  #16  
Old Mon 03 November 2008, 19:49
cncb
Just call me: Brian
 
Connecticut
United States of America
Gerald was right, it does even run if you completely restrict its airflow. Anyways I figured it out and it works now. Gosh its always those SIMPLE things that get you; and Gerald called it the backplate was touching the impeller. And not even that much but JUST enough to stall it. I cut the area back a bit (the hole cutout) and cleaned it up, put the fan back in wired it back up and shabam its beautiful. I ran it for a few minutes and just smiled

Darn the geckos don't even get warm now, it's like the heatsink is working the way it is supposed to!?! /sarcasm

Anyhow thanks guys as always
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  #17  
Old Mon 03 November 2008, 20:45
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
I'm still amazed how a guy, half way around the world, can troubleshoot a problem, and find the solution.

Gerald did this on my MM more times than I care to admit.
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  #18  
Old Tue 04 November 2008, 04:47
cncb
Just call me: Brian
 
Connecticut
United States of America
Yes the wise Gerald, he's a bank of info just like many members on this board. That's why I try to share and give back whatever I got from DIY cnc because without helping each other and what not; this wouldn't be possible at all.
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