Next interesting project, Lagunmatic CNC mill

On Sun, 23 Sep 2012 20:25:50 -0500, Ignoramus11296

Dynapath control. Good machine!
Gunner
-- "Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

At this point, I have gotten it to power up and to move the axes.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus11296 wrote:

If it has a standard 3-phase motor for the spindle, then it may be easier to replace the whole VFD than mess with repairs. Most likely if the brake resistor smoked, the power module that controls the brake has blown. If it has a separate transistor for that, it is repairable. if it is an all-in-one power module, it does not make sense to repair it, as your cost on a new module could be greater than for a whole surplus VFD.
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I spent a while on my knees today in front of that VFD.
It is a Yaskawa G3 branded Saftronics.
Supposedly, even with the drive wired for remote operation, I could make the motor jog by pressing the jog button on the keypad.
Unfortunately, pressnig the jog button seems to do nothing, 00.0 is displayed as frequency and the motor does not jog.
My main question, as of right now, is how can I establish the condition of the power module. How can I find out if it is good or bad?
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Schematics, Ig?
You can't do much without them, and worlds of good with them.
LLoyd
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

    [ ... ]

    [ ... ]

    Absence of the brake resistor should not prevent a jog (or a normal forward or reverse operation), just make it slower to get down to a stop, so the jog would likely overshoot the target position.
    This is the spindle motor, is it not?

    Can you identify which leads feed the motor?
    What horsepower range does the motor have?
    Do you have a spare VFD somewhere within perhaps half that horsepower range?
    If so, you should be able to re-connect the motor to the spare VFD and test it by spinning the motor up.
    If it doesn't -- consider the motor winding to be a likely problem. Measure resistance between all three lead pairs. If any one is different from any other (other than a few percent), it is the motor. An open or a shorted winding. (But the VFD should display an error message in the case of a short, and it should show a virtual speed in the case of an open -- at least until the current in the one remaining path is enough to force an error message.
    If it does spin the motor up -- then back to the original VFD. Is it possible that you need some other signal to enable the operation? Perhaps an axis limit switch is enabled, blocking operation?
    And there are lots of options to most VFDs. Perhaps one has been set to inhibit jog operation?
    Back to the brake resistor. Have you pulled it and measured its resistance? If it is shorted, it will probably prevent motor operation totally -- unless it is disconnected.
    The other option is the failed brake switch resistor.
    Or perhaps something got into the logic and fried it, but if that were the case, it would probably not even be able to display the 0.00
    Good Luck,         DoN.
--
Remove oil spill source from e-mail
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Correct. It should show an error code upon start up.
VFDs are pretty sharp....
Gunner
-- "Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I do not think that it shows any error. This is why I doubt if there is anything wrong.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus11519 wrote:

Does it clunk when power is applied? Most mid-size VFDs have a soft-start feature to save the rectifiers and capacitors from the power-on surge. They charge the cap bank with a resistor and then shunt out the resistor with a contactor. Is there a neon light in there to indicate the cap bank is charged? You can often see this through a grille on the side of the unit or when the cover over the terminals is off. There is usually a warning label that says something like "do not touch wire terminals when this light is lit". Small VFDs often operate the logic supply from the main cap bank with a switching supply. Some larger and older VFDs have a separate transformer and power supply for the logic, and may have a fuse in the main power supply.
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Oh, one thing I meant to mention. The braking resistors may just LOOK cooked, but still be quite fine. With rapid start/stop or rigid tapping, they will get quite hot in normal operation.
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 25 Sep 2012 13:56:49 -0500, Jon Elson wrote:

In the picture of the braking resistors, <
http://igor.chudov.com/tmp/Lagunmatic-CNC-Milling-Machine/Lagunmatic-CNC-Milling-Machine-0014.jpg
it looks to me like the ceramic core of the lower-left resistor is showing where wire ought to be. But sure, those resistors could still be quite fine.
--
jiw

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 28 Sep 2012 17:39:16 +0000 (UTC), James Waldby

Fire, what fire? <sigh>
--
Never trouble another for what you can do for yourself.
-- Thomas Jefferson
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Those are glass covered - beer color glass - and that allows them to get hot and re-flows the glass over the wire, protecting it from oxygen. They were really over laoded and were red to white hot - the one on the right boiled making foam out of the glass.
Motor or tube short can do that - depending on the circuit.
I have a number of large ones - several 8 ohm that are larger than your arm.
Martin
On 9/28/2012 12:39 PM, James Waldby wrote:

<
http://igor.chudov.com/tmp/Lagunmatic-CNC-Milling-Machine/Lagunmatic-CNC-Milling-Machine-0014.jpg

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
James Waldby wrote:

<
http://igor.chudov.com/tmp/Lagunmatic-CNC-Milling-Machine/Lagunmatic-CNC-Milling-Machine-0014.jpg


I can't really even tell what I'm looking at. But, it does look pretty burned, not just a little overheated. In this case, I think the transistor in the VFD that turns on the braking resistor failed shorted, applying continuous 340 or 680 V DC to the resistors, when they were designed for short blips of current when the motor is slowing. A good chance the rest of the VFD is fried, too. It would likely be easier to replace the whole VFD than try to source the right power transistor and hope the control logic wasn't the real problem.
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

VFDs have been dirt cheap on Ebay in the last couple years....
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 24 Sep 2012 21:38:03 -0500, Ignoramus11519

Then why do you think the braking resistor is blown? Most...most VFDs will diagnose that as well during startup.
Not all..but most.
And keep in mind..a braking resistor will not generally be involved in starting...only in serious speed changes and stopping
Gunner
-- "Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Gunner wrote:

Would there be a market for repairing those small VFDs?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are quite a few repair outfits. I am friends with one.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 25 Sep 2012 07:37:32 -0400, "Michael A. Terrell"

There are a number of companies that do just that. Get set up..and you will have my work as well.
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.