Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Glenn on November 03, 2006, 02:03:04 PM
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Hi guys,
The temperature took a dive in the shop last night, and today, my geckos won't even light up.
Everything was working fine for the last 2 months, in fact, I've been slowly turning up the rapids
from a comfortable 25ipm's to 49ipm's just to see what they will consistantly do, so did I maybe break the geckos? or
possibly just the power supply?
The voltmeter on the output gives about 3 volts dc,should this be 24?( It is a 24vdc power supply).
Gecko G201's
24vdc power supply
282oz/in. motors
Thanks,
Glenn :)
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If its a 24vdc power supply that is what you should get. Make sure there are no loose connections, check the ac voltage going in to the PSU and also the ac coming out of the transformer, it should be about 17vac for a 24dc power supply.
Hood
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Robin,
Thanks for such a fast reply,
I double-checked for loose connections,all seem fine,
the ac voltage going into the psu is correct, but I don't
know how to get at the ac output from the transformer,
it is on a circuit board, and any contact points seem to be buried.
More info...it has one green led that doesn't seem as bright
as it was before. It is lit when unit is plugged in.
When I took the lid off, I saw a fuse, but it is in tact.
Would bringing up the speed of my motors burn up the
psu?, or is this impossible?
Thanks,
Glenn
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Not, dont think there is any way the motor speed would burn out the psu.
Hood
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It sounds like a power supply issue to me. Maybe it is possible by increasing the acceleration (if you did) that the extra current draw to accelerate faster damaged the power supply? Or if the shop got super cold quickly maybe expansion/contraction occurred on the circuit board and broke some component (although that's a real loooong shot).
What is the amperage rating of the power supply and how heavy are your axis?
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Hi Marcoose,
The amperage rating of the power supply is 4.5,
and the motors are 282oz/in, the axis weigh very
little, (sherline lathes are tiny-but should do until I
can move up to a heavier lathe)..the motors don't
seem to bog down under motion, but the red light
on the geckos always dims when the motor is
activated. Is that an indication that the motors are
starving for more power?
Thanks,
Glenn
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Nope, my LEDs dim as well and I have plenty in reserve so I think its just normal.
Hood
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take a reading at the power supply with nothing hooked up to it. it should read 24v. Then hook up each item requiring 24 v until you see the voltage drop that will be were your problem is. On a dc circirt if you get a short or your power supply is going you will lose voltage. (Dim LED lite).
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Hi, Glenn
Get your Volt-meter out, on your Gecko's, Black lead on Power Gnd, Red lead on +24 to 80 volt terminal's is the 24 volts there Yes -Continue
Checking Dir and step terminal's ( Step term is harder to check depends on your Pulse's Per Step).
Black lead on Dir terminal , Red lead on Common terminal , jog the axis your testing one Direction, should have 0 volts, Jog the other Direction you should have at lease 3.5 to 5 volt's.
Your probilly missing eather the 24 volts or the 5 volts.
Let us now, Hope this Helps.
Thank's Chip
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Great advice gentlemen!
I unhooked the psu from geckos to eliminate all possibilities, and hooked up the voltmeter, and the 24volt psu
only gives 3volts dc... I'd say you guys have solved another mystery without even breaking a sweat!
At this point, I will contact the seller of this psu, and see if it's still warrented.
Again, many thanks to all,
Glenn
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Well, here's an update:
My supplier was great about sending another psu - no charge!
Bad news, after a few good and strong hours of use, rapids of 45ipm's,
cuts of 20 ipm's, I put it to bed, only to have it die the next day
upon first turning it on! No smoke, no nothing, it just wouldn't light up the geckos
and the psu's led light is half lit.
Could I have a bad resistor? You know, the one that jumps over 2 of the gecko's
terminals?
Mariss (Gecko email) initially looked at my motors and psu and suggested I
use a 33k resistor for this task-ok but how many watts? All I could find at
radio shack were the 1/2 watt, 5% tolerance size. So that's what I used.
Did I get the wrong size? How does the resistor affect the psu and / or
Geckos?
Thanks ,
Glenn
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Hi, Glenn
The Watts docent matter, its the 33K(33,000 Ohm) value thats important, It just sets the current limit in the Gecko to match your stepper max current.
Sounds like your power supply i sent up to the task at 4.5 amps.
If all 3 axis are using 33k resistors on your Geckos then your at about 7.5 amps draw on your power supply, thats way more than your power supply can handle.
Time to get a Bigger Power Supply, More Amps at least or reduce the Current draw on your steppers, which will reduce your stepper power.
Your Geckos are rated at 24 to 80 volts your at the bottom of the voltage level.
Steppers need around 10 times there voltage rating to get top speed and torque.
You should get a 70 volt or so supply rated at least 8 amps for your current setup.
Thanks, Chip
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Thanks, Chip,
I am looking into gathering all neccessary parts to Build My Own
psu (scary thought-hope I don't fry motors,geckos,and such :D) I am
looking at Bob Campbell's site on how to build one.
Chip, do you know a site that simply has a detailed
grocery list of all components needed, or are there too many variables
and size considerations to throw all the parts in one bag?
I am definately not a schooled man, and what I do know about wiring
I have been gleening from sites like this one (this site is tops!).
I appreciate your help!!
Thanks, ;D
Glenn