[SssonMachine]

1996 vmc15xt with 88hs control. Started it up yesterday morning and it started with a parity error. Went through all the rs-232 stuff and had it fixed, I thought. Started the program and it faulted out on motor overload on the z axis. Now the rapid movements are screaming fast. If I don't turn the rapid to 25 percent it will throw a motor overload, and it does this on every axis. I have checked the power coming in, its 233-236 all legs there, checked the parameters and they are good. Did the zero memory thing, 5 and 12 volt dc power is on. On this machine it does not give me the option to change the max ipm but the 94 does. In mdi I did a g1 move at f100. and it took 5.9 seconds so the feed is close. Any ideas? I can not find anyone to come and look at this machine and I a bunch of work sitting here. Not sure if I should order a new spindle drive for the 94 and hope that solves all the issues with it or wait and see if I can fix the 96.

[ASIGuy]

Sir, I hear you had a problem with your RS232 and fixed it. Let me know if this is not right and I will send you a RS232 troubleshooting guide that will nail down the problem for you. The second issue I hear you speak about is the axis alarms. You say you have checked the low voltage power supply and have a good +-12 VDC. What is really important is your 5VDC. It must be between 5.1 and 4.9 or you will start to have trouble like you are seeing. I would also check the ground to your machine and make sure it is solidly grounded. One last task I would recommend is to remove each of your controller cards, clean the gold tabs with scotch brite, brush them off and reinstall them. Make sure they seat firmly and connected back up the bullet connectors that you pulled off. Make sure they are tight in their receivers. Power up and see what you come up with. Let me know what you are seeing after completing my suggestions.

FadalCNC.com Tech Support

[SssonMachine]

I have 5.17 dc volts. Is that out of range enough to effect things?

[ianagos]

Seems a bit high

[SssonMachine]

Machine is up and going like normal again. Talked to a guy and he said zero the memory again and that worked. Why it did not take the first time idk and im still stumped at what caused this but im glad to be up and going again.

[ianagos]

Strange but at least it’s good now.

Whenever mine acts weird I just reset it and pull the cards out.

[ASIGuy]

I am surprised that you are not getting weird alarms as high as the 5VDC is. As a rule, you need this voltage 4.9 to 5.1. If you start seeing odd problems with the control happening, I would first replace that supply. Make sure you are reading the voltage with a digital multimeter that is calibrated.

FadalCNC.com Tech Support

[A_hobbyguy]

Scotchbrite on gold fingers is a horrible thing to use and is setting yourself up for even more trouble in the future because you are exposing the underlying nickel & copper which oxidize. Gold doesn't oxidize to form an insulating barrier.

The gold is only a few MICRONS of plating and only needs a degreaser/cleaner.

The tin plated edge connectors were a totally different story and did need mechanical cleaning to cut the oxide. Scotchbrite, OK sure.

"Contact cleaner", nothing more on gold plating. A can of the good stuff is not cheap...

[A_hobbyguy]

I am surprised that you are not getting weird alarms as high as the 5VDC is. As a rule, you need this voltage 4.9 to 5.1.

FadalCNC.com Tech Support

TTL chips are rated to +/-5%, so I'd like to know where this crazy spec is coming from.

What matters is the voltage at the chip, not the power supply. Because you get drops from backplane traces and cables, you actually want the supply a bit high.

Central power supplies are usually adjustable with a trim pot, so replacing it if it was off tolerance (which I don't think it is) is a bit extreme.

Hit the memory (or other) chips with freeze spray to see if they flake out. If so, replace them.

I'm an EE, in case you didn't figure that out.

[ASIGuy]

Sir, you are actually correct. I have a degree in Electronic Design and know for a fact that you are right about about the TTL tolerances and prom chips inside the power supply. Here is experience talking however; if your 5VDC is below 4.9VDC or above 5.1VDC you will have problems. These boards and processor board draw so little current, the voltage drop to the proms is minimal. You need current to flow through resistors, weak solder joint, bad connector or something that provides resistance to the supply to drop that voltage. In this case, what you see at the processor input will be the same as the voltage read on the power supply. Most machines have a nominal 5VDC and have no problems as to the replacement supplies.

This assumes you have already cleaned all connectors on the boards and gold tabs as well as making sure all connections are clean and tight. If you are not sure, take a DMM and measure across the connector and see if you read any voltage. If none, this means no drop of voltage from the supply.

Long story short, you replace the power supply if it is not within the parameters above and you save grief with odd issues with your machine.

FadalCNC Tech Support

[warrenb]

I had horrible problems with one of my Fadals exactly what you described but were all traced to faulty grounding. A simple swap to proper grounding points solved all my problems.

[ASIGuy]

It may be high but not high enough to cause this problem.

FadalCNC Tech Support

[ASIGuy]

Sir, let's get back to the rapid issue. I assume it is still far too fast and still having to keep the rapid at 25%. I would try replacing the clock card (1020) and see if this helps. It is this card that controls the feed rates and rapids if I remember right. It's a quick test if you have another machine. Just take if out of the good machine and put it back in the bad machine and see if the rapids are still out of control. If so, put them back. I would next consider a problem with your CPU or Software module.

Instead of guessing and losing time, you can send the boards to us for troubleshooting on our test machine. It takes less than a day to come to the problem and solution if indeed you have a problem in your card rack somewhere. We charge $350 for the service and saves you down time, service calls and from shipping boards back and forth and losing more time and money.

Let me know if you want to try replacing the processor and software module and we can ship them out to you when you are ready.

Either way, we can help. Just let us know.

FadalCNC Tech Support