Weird voltage problems on 4020

[andy.f]

I just got an old 4020HT with 88HS from -93 installed in the shop and cant make it run.
I seem to have too low voltage from the DC power supply on 5VDC, but -12V and +12V are ok. the max I can get is 5,06VDC after I remove all control cards and remove J9-J13. In this state I can also get 120VAC from the T-816 transformer. Reinstalling the cards I hoped to find the culprit, but it seems like each card is pulling 0,2 - 0,3VDC which means I cant get enough to keep the amp chassi from going into E-stop. Also even though all cards does not blink when installed together, they all blink when installed one at a time, except the A axis. When I try to check for AC ripple I get 10VAC on the 5VDC and 26VAC on the +12VDC. This is quite a lot of ripple, but all my DMM's are really cheap and can not even measure AC current. Only DC current.

Question: Is this a realistic AC ripple? Can it really be that high or is it a bad multimeter?

Since the relays work and let the control 120VAC through if no cards are installed they obviously work. It seems the trick is to get around 5,1VDC while all cards are installed, but how?

The machine used to have a 4th axis installed, but was removed before I got it. the drive card and amp is still in but I can not see any plug on the drive card. I guess I should disable the axis in the control and remove it in case this is causing problems but dont know how?

The Baldor Vector Drive, model INV-0049 has a diagnostic page and says the bus voltage is 345V. the strange thing is that I am only feeding 210V 3 phase to the machine. The log page has 31 identical entires with "DC bus high" so I am starting to wonder. Am I missing something?

As I have no manuals and all the currently available manuals from the Fadal, compuserve etc. web sites are for newer machines with other boards, vector drives etc. it is quite tricky to trouble shoot this.

I will start by investing in a proper DMM!

Any help would be fantastic!

Andy

[gar]

071209-2032 EST USA

andy.f:

A capacitor input filter following a rectifier and no load will produce a voltage on the capacitor approximately 1.414 * Vrms. So your 345 VDC is not unlikely if you have some selectable transformer taps in the control. Your 210* 1.414 calculates to 297, but 240 * 1.414 = 340 VDC.

Your other question on ripple might result from the meter design, otherwise you have a bad low voltage power supply. Put you meter in AC volts, like 10 V range. Check the voltage of a 6 battery. If you get anything greater than millivolts, then your meter, in the AC position, does not use a series capacitor to remove the DC component.

.

[andy.f]

Thanks Gar!

The transformer is tapped to give 240VAC so your maths as up, however is this ok for the vector drive? The various manuals say to feed either 230VAC or 240VAC 3 phase to the vector drive.

I will check the DMM's on a battery, (why didn't I think of that?!?).

Another part of the story is grounding. There is no proper ground work in the building (I am in Thailand), so I dug down a large wire into the ground. That seems to work fine with the other VMC's and Lathes we run, but maybe the Fadals are more demanding. I will try to dig deeper for the Fadal!

It is tempting to bypass the E-stop circuit to see if the machine runs, but the fact that some faulty component might do damage if the circuit is bypassed makes me think twice.

The trouble shooting manual doesnt really cover HOW to check components, it just say "check this and check that" etc. Are there some simple trick to check a solid state relay, ice cube relay and capacitors?

Andy

Originally Posted by gar 071209-2032 EST USA andy.f: A capacitor input filter following a rectifier and no load will produce a voltage on the capacitor approximately 1.414 * Vrms. So your 345 VDC is not unlikely if you have some selectable transformer taps in the control. Your 210* 1.414 calculates to 297, but 240 * 1.414 = 340 VDC. Your other question on ripple might result from the meter design, otherwise you have a bad low voltage power supply. Put you meter in AC volts, like 10 V range. Check the voltage of a 6 battery. If you get anything greater than millivolts, then your meter, in the AC position, does not use a series capacitor to remove the DC component. .

[fadalman]

My 4020 did the same thing .I tried changing relays and about everything else. I t ended up being the power supply. I could get close to 5v but it must have been not enough>

[andy.f]

Originally Posted by fadalman My 4020 did the same thing .I tried changing relays and about everything else. I t ended up being the power supply. I could get close to 5v but it must have been not enough>

Were you able to fix the power supply or did you have to replace the whole thing?

The machine was running right until they shipped it so it is a bit strange as I would imagine this type of error is due to wear and not impact during shipping.

Andy

[gar]

071210-1205 EST USA

andy.f:

A vector drive is essentially a variable frequency to an AC induction motor. See:
http://www.reliance.com/pdf/drives/w...pers/D7161.pdf

Incoming AC line is converted to DC and from this DC the vector drive generates the desired AC variable frequency.

Your 245 V might be slightly above what the nominal value should be, but solve your low voltage power supply problem first.

What you need in your plant is a heavy (maybe 0000 gauge to minimize electrical noise voltages) copper ground wire that connects all electrical equipment together and at the service entrance connects to a grounding system. Individual ground rods at machines without safety grounding wiring between all electrical equipment is not safe. See the US National Electrical Code.

Is your power source a 3 phase delta or "Y", and how is it grounded?

.

[elwoodbeauchamp]

Hi Andy.F...The shop I worked in for some years purchased a 4020 and we were advised to draw power directly from a 3 Phase Transformer and place it as near to the machine as possible. This must have worked as we did not ever have a problem related to any power issue. Also, as for the transformer grounding, we drove a 6 foot ground rod through the floor as close to the Transformer as possible. I do not have the KVA of the transformer on top of my head, but you can calculate this and kick it up a notch for good measure.

Frank, Adrian, David and Larry say Hi. (the names of 4 of the 5 brothers who founded FADAL) in case you didn't already know...lol

Elwood

[andy.f]

Originally Posted by gar 071210-1205 EST USA andy.f: A vector drive is essentially a variable frequency to an AC induction motor. See: http://www.reliance.com/pdf/drives/w...pers/D7161.pdf Incoming AC line is converted to DC and from this DC the vector drive generates the desired AC variable frequency. Your 245 V might be slightly above what the nominal value should be, but solve your low voltage power supply problem first. What you need in your plant is a heavy (maybe 0000 gauge to minimize electrical noise voltages) copper ground wire that connects all electrical equipment together and at the service entrance connects to a grounding system. Individual ground rods at machines without safety grounding wiring between all electrical equipment is not safe. See the US National Electrical Code. Is your power source a 3 phase delta or "Y", and how is it grounded? .

Thanks for the info on the vector drive. Even if the DC power supply is bad I will have problems getting the right voltage if I jumper the transformator to feed 230VAC to the spindle inverter. With this I only get 114VAC to the DC power supply which should have 120VAC and I only get 90VAC to the amp chassi that should have 95VAC. Unless there is a way to modify the transformer. I have heard nominal +- 10% is ok. Anyway the voltage here is not rock solid.

I bought the islands only AC clamp style VAC meter, but it shows only down to 0,1 V resolution. sometimes I get 0,1VAC on the 5VDC bus, but the +12V and -12V seems clean. As I get a voltage drop of about 0,02 - 0.03VDC per card I install in the cage it would seem likely that the DC power supply is bad, unless of course poor grounding could be affecting to the same extent.

Regarding grounding I have checked the Fadal recommendations and US specs, but I wonder what I would do if I only had one machine and one fat copper wire leading to a ground rod? Here in Thailand the power comes nominal 380VAC 3 phases at 50hz plus what they call 0. To create single phase 220VAC you pick one phase and the zero. There is no other ground wire. So grounding is something you have to do yourself. We dont use copper pipes for water. All is PVC. The only thing I can think of is the copper rod in the ground. Did I miss something?

All the best and thanks for your help.

This forum is better than school!

Andy

[andy.f]

Originally Posted by elwoodbeauchamp Hi Andy.F...The shop I worked in for some years purchased a 4020 and we were advised to draw power directly from a 3 Phase Transformer and place it as near to the machine as possible. This must have worked as we did not ever have a problem related to any power issue. Also, as for the transformer grounding, we drove a 6 foot ground rod through the floor as close to the Transformer as possible. I do not have the KVA of the transformer on top of my head, but you can calculate this and kick it up a notch for good measure. Frank, Adrian, David and Larry say Hi. (the names of 4 of the 5 brothers who founded FADAL) in case you didn't already know...lol Elwood

Hi Elwood,

This sounds like my set up. Here we get 380VAC from the wall so I use a standard step down transformer for our Japanese machines that usually run on 200VAC. We get 195 - 220VAC from the step down depending on the time of day. The Jap machines have no problem with the fluctuation. I also have a Bridge port with a modern US made control. The Bridge port wants 460VAC 60hz, but we can only give it our raw 380VAC 50hz, but it has been running great for years.

The Fadal has the T-816 trafo so it can accept 190 up to 480VAC, but the MOV suppressor is the 250V version so that is why I feed it 200VAC from the step down. Ground rod is the only means of grounding we have. Most people in thailand dont ground anything so there is pleanty of space for stakes!
I will try to wire all machnines together and then in to a serious copper stake driven down 2 m into the ground. Maybe this cures the problem, maybe not.

Cheers,

Andy

[fadalman]

If you have the power supply that looks like one out of a computer you can buy one for a computer (make sure it has enough watts) then go on the web and find atx wiring diagrams. You have to bundle same voltage wires and hook them to the board.Also it will show which 2 lines have to be jumped to make the power supply come on.I used a atx 50 watt just make sure all voltages have ample watts. Mine cost 50.00 to fix.

[andy.f]

Originally Posted by fadalman If you have the power supply that looks like one out of a computer you can buy one for a computer (make sure it has enough watts) then go on the web and find atx wiring diagrams. You have to bundle same voltage wires and hook them to the board.Also it will show which 2 lines have to be jumped to make the power supply come on.I used a atx 50 watt just make sure all voltages have ample watts. Mine cost 50.00 to fix.

Tempting, but I have the old style with a big wire spool. I have tried to find specs on it, but all current literature from Fadal are for newer machines. Mine is from 1993. I would need to run the machine, (which I cant!), to meassure how many amps it draws. I wonder if I would break something if I try with a computer power supply with too low wattage or if it would be ok just for testing?

Andy

[fadalman]

It might be ok seeing as that when they fail they dont put out enough power and the machine doesn't work. But there is a relay on the board that is powered by the power up button , so power is not applied to the computers until the rest of the machine is powered up and it stays on after you hit the button on the back.