Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jimthefish on February 22, 2013, 07:21:05 AM
-
Hi Its me again, I still get the occasional program stopping because Mach tells me a limit switch has been triggered although non of the warning on the diagnostics page show any faults. I have rechecked and earthed the machine, BOB and spindle drive board, shielded the wires, set the debounce on several occasions, changed the computer and checked the switches but I still get the machine stopping once a day. Luckily the stop is instant so no damage or cutter breakage has occurred. My questions is in the general config page there is a tick box to "use WatchDogs" if I unticked this box will it stop the limit switch signal stopping the program, or is it unwise to do so as it removes the overtravel limits and other protection systems. Or has it nothing to do with my problem. Jim
-
If the message you get is Watchdog triggered then disable it, if not then its unlikely to help but wont do any harm disabling.
Regarding not seeing the LEDs on the diagnostics page, that is normal with noise issues as they are so quick the screen does not have time to react due to the screen refresh but the driver sees them as it is fast.
Hood
-
BTW that is why Industry uses 24v for signal wiring, very resistant to noise due to the big difference between a high and low signal threshold. I am glad to see at least one company has seen the benefits of 24v I/O as it makes my life a lot easier as I dont have to have extra interfaces to convert the 24 to 5 and vice versa.
Hood
-
Cheers Hood whats got me baffled is the machine has been working fine for some 3 years, so whats got into it is beyond me. You can see from my previous threads I think I have solved it only for it to return a couple of days later. I'm running on the latest Mach software since my computer failure early this year. Is it worth going back to the older version, I must have it on a disc somewhere or am I clutching at straws. Jim
-
Could be something gradually dying, eg a VFD may produce more noise as capacitors start to go.
You could try an older version, I do know there are lots of issues with the latest lockdown and development versions and Turn and I do have at least one issue with them and mill but nothing like limits tripping. You can get older versions on the ftp site if you dont have them.
Hood
-
Jim, it would be easy enough to load an older version just to see if it helps. I don't think it will, but can't hurt anything to try as long as you back everything up before you do. Just copy your whole Mach 3 folder and put in on a thumb drive. As to why it is doing it now after doing for a while you must understand, many things effect EMF. Humidity being one great example. Ever slide your socks on the carpet and get a shock when you touched something metal? The results vary greatly with the relative humidity. How about rub your hair with a balloon? That doesn't work if your hair is wet. Noise can be a real PITA to put it lightly. I remember a while back a guy had a machine that had been running fine, all of a sudden it started throwing false limit switch triggers. The problem was he had added a fluorescent light over his machine. So, what has changed that effects your machine?
BTW that is why Industry uses 24v for signal wiring, very resistant to noise due to the big difference between a high and low signal threshold. I am glad to see at least one company has seen the benefits of 24v I/O as it makes my life a lot easier as I dont have to have extra interfaces to convert the 24 to 5 and vice versa.
Hood
No truer words have ever been spoken Hood!
Brett
-
Thanks for the advice Chaoticone. As I have mentioned in previous forums I have an old 1988 LYNX 80 spindle drive unit, its right next to all the other electronics and looks like something out of an old TV. I have looked at it and I think I could move it into a separate box on the back of the machine. This is a standard metal electrical enclosure and will be about 60cm for all other electronics, is it worth a try our does the interference go down the control wires. Jim
-
Jim, it may well be worth trying. The interference will go down the wires but shielded cables should eliminate the worries of that. This is why you only attach one end of the shield, at the controller. You simply cannot eliminate EMF, you can only try to guide it where you want it to go. What you hope to do is give a path of little resistance to ground and away from your low voltage bits. Ground loops are like big antennas, they simply distribute the noise all over. It gives them a path to run around freely wreaking havoc without ever having to go to ground.
Brett
-
Hi Chaoticone, just looking at my Lynx80 Spindle drive board and thinking about moving it when I noticed a burnt thingy. Its on the 240v power in line (see picture) the first electronic connection on the board. In the manual it says "Diodes D34-D37 form a separate full-wave, fused for motor-field supply. Field circuitry is protected against high field-transients by capacitor C6 and varistor VDR1," it looks as if the capacitor has blown (C6). The spindle drive board works perfectly so don't want to mess unless you thing this could be giving my limit trigger fault?
-
Looks like a RC Network, ie a capacitor and resistor in one package, could well be causing your issues ;)
Hood
-
I've been having the same problem... and it does seem related to newest version.
I've never had the problem before... but since updating... I've had it.
Also looking at the first page of this forum... there are quite a few topics on this. Coincidence?
-
Cheers Hood, had the magnifier on it and it says 440G, I will go down and have closer look in the morning, I have noticed a couple of times the spindle seems to be running faster than my M3 programmed speed, but it cuts fine. Thanks mate
-
Johnny, again, going back to an earlier version would be simple enough to try. Let us know if it helps.
Yeah Jim, as Hood said, that could be the source of your pain.
Brett
-
Hi Jonny I first thought that the upgrade was the cause but am moving away from that being the problem, I think my problem is electrical noise. I was advised to download the older version of Mach to see if it solves the problem (its still on the Mach download section of the web pages), but will replace the faulty part on my circuit board spindle drive first I have a feeling that is my problem. As Hood and Chaoticone say it plays havoc with 5v control signals. Keep you posted. Thanks for your thread. Jim
-
Hi Hood and Chaoticone, well moved the Spindle Drive and solved the trigger problem, but the spindle has started creeping again so going to replace that burnt out RC Network thingy. Its so burnt I cant read the type it is. On a very badly photocopied electrical drawing it says 440G and a symbol of a Thermistor but the written text says its a varistor and along side it is a Capacitor (C6) which I think is OK. any suggestions as to what rating it might be? or do I go by the size and wire spacing on the PB?
-
:) Good deal Jim, that's great news. I know what a pain noise can be. I have no idea about your crispy component though. Maybe looking in Allied or Newark will give some ideas. Size and spacing may well be a big clue. I just got a 300 watt resistor for a VFD. Hated to spend the money as I have a couple the exact same size (wattage and physical) but the one I needed was 70 ohm and the ones I have are 26. So, long story short, I have noticed the size of a resistor usually gives a good idea as to the wattage rating. Has nothing to do with resistance value though. I also have no idea if that is a standard that is adhered to across the board or just the product of common manufacturing processes or what. I understand why larger wattage resistors are larger in size but no idea if you used different materials if they would have to be a certain size because of a standard. I also know I have one PC that is 17 x 16 x 7 and another that will fit in one of the 5.25 bays on it that has more ram, storage and a faster processor than the big one.
Brett
-
Jim, I am thiking the component is something along the lines of this
http://uk.rs-online.com/web/p/rc-network-capacitors/2067831/
If you could find someone with a similar drive with the component in good condition it would maybe help match in the capacitance, voltage etc.
Hood
-
Cheers Hood, I think all the other LYNX drives are in museums,did find a picture of one on another CNC site but guess what the same component was burnt out. Looked on ebay and there are a few components that might be correct, as you said its just getting the right one. Its strange worked most of the day on some mementos for a child's charity with no problem. Then after about 4 hours I heard a buzzing from the motor and it started to rotate. I can live with it till it gets warmer and I don't freeze, I just turn off the machine to change the tooling. Going to go and clean up the workshop this morning so will have another look to see whats written on it, keep you posted. Jim
-
Hi Hood I was busy looking at my pictures of the spindle drive when I noticed there was another capacitor exactly the same shape and size further down the input line. It measures and looks exactly the same but not burnt like a crisp. Its made by RIFA and has the following markings on it 1000v/500v MP
PME261
40/07/0756
On the top is 0.1uf which is the only thing I can read on the top of the burnt one. Does this sound feasible. I have looked around but cant find any on the net except for these http://www.ebay.co.uk/itm/121068277543?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 but think the 1000pf are too small. Jim
-
Like this
http://uk.rs-online.com/web/p/paper-capacitors/4148689/
Hood
-
Cheers will oder them tomorrow. Jim
-
HI everyone,
As well as many others i have a problem with phantom limit switch triggered symptom.
De-bounce has been set to 50k. Still problems. All the wires are grounded.
There are lots of threads about it but as they say one pic is worth of thousand words. Not being skilled in electronics, can anybody take a photo of capasitors being istalled on BOB or atleast some wireing scheme.
thanks
Taniel