Grizzly g0720 x4

Total new guy here. Not cnc related but while surfing for answers to my mill problem, cnc zone popped up with at least some information. My mill crapped the bed, Grizzly tech help is useless. I was using the mill, shut it off, upon trying to restart, no go. Turned the spindle, felt lumpy in rotation. Took the motor out, spins freely on the bench. Reinstall the motor, connect, lumpy again, wtf. Seems to me that the resistance is the motor generating power when turned and the lumpy rotation is pulses of magnetism. Spins ok, installed and disconnected. I assume the motor is ok. The fast blow fuse on the circuit board is blown, none to be found so cobbled up a fine wire across the ends of the fuse. Motor disconnected, instant fuse pop when the main power switch is turned on. The head lift motor still works normal. I'm looking for some input to help isolate the fault. Had the board out, don't see any burned spots or obvious blown components. Just don't want to replace the board to have it go south immediately. I'm hoping some one here has some insight for me. Thanks

Hi, the fact that the "fine wire" blew immediately is no indication of a fault in that direction.

You need a fuse of the same rating to carry the current for the application, and a slow blow one to prevent a surge on switch on from blowing it again.

Blowing a slow blow fuse has to be a find the fault or cause before you replace the fuse.......or you could burn the board that the fuse is trying to protect.

If the motor is "lumpy" out of the drive train the bearings are gone or something is inside that shouldn't be.

If the spindle is lumpy with the motor out the bearings could also be gone.

You could have a DC short to the motor creating a braking effect if the motor is an AC synchronous one, but if it's a BLDC type with VFD, that is with permanent magnets and a DC supply to the field coils, then the control board or the VFD is suspect.

That is pure guess work from here, but areas where I would check first.
Ian.

Thanks for the quick reply. The motor spins good when disconnected from the board. The spindle is good. I'm leaning real heavy towards the board. The motor is a brushless dc 1500 watt. There was no actual load when the cobbled fuse blew, just the power switch turned on. The board is $460 US, be $600 by the time I get it here. Expensive trial and error if something else is causing the fault. I'm hoping to get some values for testing with the dvom. No short to grnd from the other motor wires, but I don't know what res values on the winding wires should be.

Hi, replacing a fuse....any fuse when it blows.......is a recipe for disaster without FIRST finding out why it blew.....that's the whole purpose of a fuse to protect the circuit it's part of.

If the motor is "lumpy" when it's at standstill, IE no power at all to it from the VFD or whatever, and that is not with the VFD turned down to the stop position... whatever....you could still have some current leaking from where ever it originates and that I suspect is a DC current causing a braking effect .......purely hypothesising here.

The brushless motor requires a DC source that turns on and off at the right moment to spin the motor as opposed to having a commutator in a brushed motor that times the switch on and off to make the motor spin and this I think is from a VFD that is also controlled by the circuit board as opposed to manually turning a knob on the VFD to get a speed change.

So you could have a board problem that controls the VFD that causes a constant DC current to the motor when it's switched off or the VFD itself malfunctioning.

It's electrical as the motor is smooth before you make the connection.

I would use a meter to check if there is any voltage/current present at the motor wiring input......motor wiring disconnected....... when the motor is not being driven.

If you don't know enough to handle electricity....don't fry the circuit board or yourself for a few dollars saved with an electronics guy.

I assume it's out of warranty so you're on your own, and the cost of the electronics guy will be as per the hourly rating for a call out to your place.

You could remove the circuit board and VFD, also the motor, and go to a tech who will then only charge you for the testing time as opposed to a call out fee......VFD's ($300 $400?) are really throw away items when they malfunction.
Ian.

Thanks for the replys. As it stands now, the board is way beyond me, don't have an electronics guy. There's only very small wiring from the switches as inputs, don't see as those could be at fault. I'd really like to be able to test the motor to make sure that it wasn't the cause of the board failure. Any one having meter values on the wires would be a great help. There's no short to grnd from the three other leads. I really like the tapping feature of this mill.

Hi, deep down in my water I'd first look at the power supply as a cause of the fuse blowing.

The fact that the fuse blew doesn't mean that you have a 100% problem with the board.......it could be doing it's job in allowing over current to flow for a short period of time while the transformer and capacitors et al are soaking up the amps when it powers up.

If the fuse was underated to carry that short time load it will blow every time......never use a heavier fuse to combat that effect unless that is the problem

The makers of that router would not be making something that is top dollar in the components so they play safe and the fuse is one way to stop a fire from happening.

I think I would leave the motor disconnected, fit another fuse, cross my fingers and hope to live longer.....LOL......and switch on again......if the fuse blows again I would also then disconnect the VFD ( if possible), fit another fuse and switch on again.

The lumpy feel to the spindle could mean you have a leak to the motor from the VFD and it's drawing more amps at switch on, so what is the VFD doing putting out current when it's not required to.

The VFD puts out controlled sequence pulses to make the motor rotate and if as you say you're getting a lumpy feel at switch on when the motor is stationary, this is DC current where it shouldn't be, or perhaps if the VFD is shot, it's putting out uncontrolled current on all phases so you get the motor in a locked state and a current draw.

The VFD gets its current from the main AC supply and then supplies it to the output as a sequenced stream of current pulses dependent on the VFD speed position controlled by the board.

However, if the fuse blows just switching the box on without any driving on any steppers or the main motor......that is a worry and needs tech time with lots of electronic knowledge.

BTW, did the fuse blow when you switched the box on after your last machining time.......I assume the box was still switched on and the motor and peripherals all switched off waiting for a signal from the PC.
Ian.

Tried another cobbled fuse. It doesn't just blow slow, got fireworks, flash pop type. Motor disconnected, just turning the power switch on. Just like a dead short to grnd within the board. Pretty well resigned to ordering a new board. This board has a lot going on, as I read it, boosts power to 230 vdc, variable speed, 1/2 speed in milling mode with instant rev, tach input from the motor for the speed readout.

Hi, isolating the motor still leaves the VFD connected and it may have expired.......I read somewhere here that the Chinese VFD's are not all that great and you can expect to replace them within a year or two from new.

I would seek out the input to the VFD and isolate it.....then do a re-fuse and switch on, but a cobbled fuse, ,ie a piece of plain fuse wire in place of a proper slow blow one will not give you any valid results.....fuses are cheaper than a new board and will still indicate a current over load until you find the part where the fuse stops blowing.

Don't rule out the power supply if it's a switch mode type as opposed to the old transformer ones......you can tell the difference in that the older type with transformers are big and bulky and heavy too, and switch mode ones are all electronic components with a very small transformer.

Practically all power supplies are now switch mode type.

What is the next component in line after the fuse or where is the fuse located in the circuit?.....

Somewhere there has to be a component that has failed and is shorting to earth or just becoming lower in value and passing more current to other components along the line that rely on it to control them.....resistors are prime suspects here as when they get hot they lose the capacity to resist the current flow....my 2 pennoth worth.
Ian.

Dead short somewhere. You need to develop your trouble shooting skills now.
I have always had problems with Syil products.

There's a pretty good review on this unit at Minilathe.com/ SiegSX4 mill. Contacted Syil, they said they use their own electronics in their equipment. Unfortunately I'm somewhat electronics challenged, without a schematic to follow, for pin point tests with the meter, there's not much hope in me diagnosing this problem. Used to do basic org chart type diagnostic tests in the automotive field, they were easy to follow for a wrench twister.

Hi, don't give in.......have a look at the board and try to see where the mains supply wires go to.

With the power switched off and unplugged.....I would trace the mains supply wires to see what is the first thing they attach to.......it will either be a transformer and a rectifier with fuses or the circuitry for a switch mode power supply......this first bit breaks down the mains supply to probably 12 volts and other voltages to feed the board components and stepper motors.

If the stepper motors are working then the power supply is probably OK.

The mains supply also goes directly to the VFD so if you have a problem there the mains fuse will blow immediately.

The VFD is a stand alone box that controls the spindle RPM and it's output wires go directly to the spindle.....it is controlled by the Mac3 software that interfaces it with a variable resistor to vary the speed of the spindle......out of the box the VFD by itself can be manually adjusted to vary the spindle speed.......it is a replaceable item and cost approx. $300 to $400 depending on it's power rating.

The more you look at the layout of the components the more you will understand what they do.......they get grouped to do their jobs.

BTW, the boards probably cost what you stated because it has the VFD attached to it as an assembly matched to the spindle, and that is the most expensive item but replaceable......the board by itself, sans VFD, is probably only about $100 at most, but the suppliers don't have separate boards without VFD's as stock items as they buy them in from China along with the machines........separate complete boards as special orders plus shipping etc.
Ian.

Good news and good news. Had another go with a Grizzly tech, together we came to the conclusion that the motor was ok. Figured I'd bite the bullet and order a new board. At our pistol club meeting last night, after mentioning my problem, no new guns till the mill is fixed, a member offered help in trying to repair the old board. Fella is a retired telecom service guy, talked circles around me regarding component testing and how the system works. Hopefully I'll have a spare board at minimal cost. I'm stoked and broke.

A little update. Installed the new board, mill is still no go. Fuse doesn't blow so progress is being made. More thinking as to how things work, the start button gives a signal to the variable control, which in turn goes to the main board. The variable control is on a small pc board. My last hope is that the crash took out the control board. Grizzly doesn't have stock, but I found a company in the UK showing stock. Fingers crossed.

The saga continues. Got the pot from the UK next day from ordering, wow. Upon installing the pot, still no go. Back to the Grizz tech guy, did a few meter tests, conclusion, no output from the board. Short story, board is going back for refund. Ordered a 1.5 hp three phase motor, GS-22po vfd and an extension cable to remote mount the key pad, from Automation Direct. Mounting the motor will be easy, still using the original belt and pulleys. Vids on you tube show successful operation of this type of drive. Hope I'll have a working mill soon. Grizzly has a mill with a similar drive on their site.

Many thanks to those who tried to help out with my problem. Have installed the motor and drive, mill works great, looks like it was made that way.

Hi, what happened about the board........was that the problem all along.....mill is now working OK?
Ian.

Sent the new board back for refund, have to wait and see how bad they do me on that. The tech guy had nothing to offer after testing for output from the board. The new motor and vfd drive is working pretty good. The belt tracks right on. Half a day of seat of the pants engineering before making a cut paid off. Only had to remake the drive pulley adapter twice to get it right. Fortunately the guy I sold the old 6019/ x3 mill to 3 years ago hasn't picked it up yet so I had it as a back up machine.

Hi, after 3 years I'd have to wonder if the guy is still of this World....LOL.

So, are you getting a new board in place of the bad one.....you said a "refund"........no chance of trouble shooting the old board........like putting in a signal with a signal tracer and see where it doesn't continue.

I used a home made signal tracer that injected a signal and you traced it round the circuit until the signal stopped where it should have been continuous.......found a couple of brand new transistors that weren't worth toilet paper with that device, not that I'm any great shakes electronic wise, but I wield a very hot soldering iron when the going is good and the circuit diagram is clear.

With board technology like this we need something that you can attach to your computer and it reads the circuit and detects any anomolies.....etc.
Ian.

I've had my Sieg SX4 (Grizzly G0720R) for a few months now and it has been working pretty well. Hopefully, it will stay that way. I suspect the issue the original poster had was a peculiar one and not generalized to all SX4's.