Component failure

[len]

I just thought I would share my experience with CNC4PC products. I had installed their power supply and parallel break out board in my home build 4x8 rougher table. After many hours of running one day after turning on the system I heard a noise and them all the stepper motors went nuts, and my computer turned off.

After doing some diagnostics, I discovered that a small trace for ground on the cnc4pc power supply blew open, and thus caused the power regulator to stop regulating thus sending 18v though my cnc system as well as my Dell computer. Result? 1-blown computer $500 (18v through the parallel port), 1- blown $350, 1- blown power supply $25.00, 1- blown LCD screen $300 and and blown break-out board.

The problem is that the CNC4PC power supply used a very small trace for ground, in no way could this handle the current draw. Once that trace blew it sent the voltage to volts which non of the 5 volt logic could handle.

So if you are considering a power supply and a break out board I would look for one that has all opto-isolated input and outputs , If I have bought the Bob Campbell's break-out I would have saved myself $1200.00 his boad is all opto-isolated with isolated grounds.

[Chris D]

Hi Len,

Sorry to hear about the doldrums of electronics failure - never a fun deal. I went through something similar last year when I goofed up and didn't isolate my outputs from a spindle driver that requires isolation.

Seeing as the trace burned up on the board, I am wondering if you were pulling too much current through that power supply? I don't know enough about electronics to know right from wrong so it is just a guess on my part. What all was being powered by that supply?

Chris

[CJL5585]

Originally Posted by Chris D Hi Len, Sorry to hear about the doldrums of electronics failure - never a fun deal. I went through something similar last year when I goofed up and didn't isolate my outputs from a spindle driver that requires isolation. Seeing as the trace burned up on the board, I am wondering if you were pulling too much current through that power supply? I don't know enough about electronics to know right from wrong so it is just a guess on my part. What all was being powered by that supply? Chris

Len,
From your post, I am assuming that you are driving the STEPPER drivers AND the breakout board from a common power supply.

I would recommend that you verify all the wiring and connections, as I believe you might have a ground loop allowing some of the driver voltages circulating thru the ground circuit.

.

Jerry

[arturod]

Len,

I am very sorry to hear you had this problem. I just checked the ground traces of the power supply and strongly disagree with you as this being the cause of the problem. The power supply handles 1 amp of current, it is very low. The trace must have blown as a result of the general meltdown you had.

The real risk of a meltdown using stepper systems comes from the extremely high voltages the drivers send to motors for very short periods of time. If at that moment there is a failure in the motor, then you have the risk of having the voltage go back to the breakout board and to the computer.

As I understand the outputs in Campbell’s board are not optoisolated since they are designed to be used with the Geckos which are optoisolated. I just went to their website and did not find specific reference to this. It would be good to ask Bob about this.

I would like to know a bit more about your setup. What drivers where you using?

Arturo Duncan
http://cnc4pc.com

[gar]

051205-1043 EST USA

All important equipment should be electrically isolated. The usual method is optical or transformer.

This means at both ends of an interconnect cable. What happens if you put 120 or 480 v on the interconnect cable if only one end is isolated?

Few users seem to realize the importance of isolation of electrical subsystems.

We sell an RS232 to RS232 Isolator. Few of our customers buy the system for isolation to prevent electrical damage, but rather their real interest is high speed and noise reduction. See our web site www.beta-a2.com and the discussion on Noise and Grounding and how by simply shorting a hot AC line to safety ground can produce damaging voltages.

My discussion does not directly relate to your particular problem, but does serve to illustrate some ways you can get into trouble.


.

[widgitmaster]

Wow!
I thought I was the only one who set the smoke alarms off!
Glad I got the Campbell Breakout board, or I would have toasted even more stuff!
Only four Gecko's died in my arms!

Better luck in the future!
Eric

[Goforit]

Hello Len
I'm planning on getting one of Bob's cards soon. I just came froms Bob's site and it states "The first and very important feature is isolation. The break-out board provides total opto isolation of the parallel port . It sounds to me like the outputs are isolated. I do not have Gecko drives so I need the isolation. I will E-mail Bob but I would appreciate some input on this card from you and others that can. I am electronicly challenged. Thanks you Steve

[len]

I'm not trashing this product because of my misfortune,however,you
should be aware that the board provides _no protection from parallel
port outputs,1-9,16,17 and the power supply on the break out board side.
The inputs of most high quality drivers are opto isulated(protected from
input ground and signal problems).your drivers would survive a breakout
board failure,your computer may not.

[pminmo]

Len,
I am also sorry for your troubles, but I would caution you on blame. Grounding through a system tied back to a computer is a double edged sword. One, properly done grounding, there isn't a huge need for opto isolation. Two, a lot of people wind up not wiring the isolation correctly so they wind up with a common ground through the system. Since you had a catostrophic failure, the computer fried and a ground land burned, it really points toward a faulty ground. The fact the the cnc4pc product failed is probably the result of the ground fail, not it doing something wrong.
Either a bad connection or miswired. Sometimes it's as simple as how plugging the computer into a different AC circuit than your control electronics.

Even with opto isolation if you don't isolate the ground/common, you could still have the failure you described.

[CJL5585]

Originally Posted by pminmo Len, I am also sorry for your troubles, but I would caution you on blame. Grounding through a system tied back to a computer is a double edged sword. One, properly done grounding, there isn't a huge need for opto isolation. Two, a lot of people wind up not wiring the isolation correctly so they wind up with a common ground through the system. Since you had a catostrophic failure, the computer fried and a ground land burned, it really points toward a faulty ground. The fact the the cnc4pc product failed is probably the result of the ground fail, not it doing something wrong. Either a bad connection or miswired. Sometimes it's as simple as how plugging the computer into a different AC circuit than your control electronics. Even with opto isolation if you don't isolate the ground/common, you could still have the failure you described.

Well Said - I agree.

Jerry

[JavaDog]

Hmm...so, was it the CNC4PC Breakout Board or their small PSU that fried?

I bought those myself, and I hope I don't run into a similar situation...

[pminmo]

Len,
can you give us a picture to the copper side of board trace that fried? I suspect there is a clue as to where your problem originated.