Did a $10 resistor take out my Vector Drive?

I recently moved my shop to a new location, during the move my SL20 shifted on the truck. Though no damage was apparent at the time, we got it set up in the shop, leveled, wired, phase checked, spindle, turret, and tailstock alignment checked, everything was within spec, though the spindle centerline offset changed by ~0.015".

We ran some test pieces, and it cut to spec.

I had maybe 10 hours on the machine since the move, and had just finished a boring operation, as the turret was returning to G28, and the spindle was slowing from ~2,200RPM (G96) we heard a BANG! and the machine shut off.

I could see the 50A breaker on the wall had tripped.

I opened the back panel and looked for melted wires or anything burnt. Though I could smell the faint aroma of magic smoke, I couldn't locate the source.

I carefully worked my way from the breaker to the Vector Drive, checking voltages, it was the normal 209 - 210.5, and 230 off the transformer tap going to the Vector Drive. Though both the Phase Pass and Phase Fail indicator were lit.

I shut down the power and rechecked all the connections, everything looked good. So I powered it up again. The Phase Fail indicator went out.

I probed the DC BUS and it read 0.0V.

I checked the Alarms, and came up with:

903 CNC MACHINE POWERED UP

160 LOW VOLTAGE

123 SPINDLE DRIVE FAULT

I cleared the alarms, and only ALARM 123 SPINDLE DRIVE FAULT came back immediately, even after multiple resets.

I checked the Vector Drive and the POWER ON and FAULT LEDs were lit, the HIGH VOLTAGE was NOT lit.

I powered everything down, ate lunch, and then disconnected the Servo Drives from the DC BUS, powered it back up, and this time the POWER ON, FAULT, and HIGH VOLTAGE LEDs let up, though the HV was dim.

I probed the DC BUS and it read 18.0V, checked the DIAG page, and it concurred.

I powered it down, waited for the HV LED to go out, then disconnected the VD, I ran resistance/diode tests on the Spindle motor, Servo Drives, and Regen coils, everything seemed to be in spec.

I pulled the VD and threw it on the bench, pulled the cover, and started looking around.

I couldn't find anything burnt, melted, or visibly damaged, except for the off-board resistor that runs between the +HVDC on one of the MG150J2YS50 IGBTs and port J5 on the top board (which looks like it feeds Q4, a G7N60C.

The tubular ceramic resistor doesn't look burned, but it did melt the epoxy near the middle, and cracked the ceramic cleanly. I can't read the numbers except:

"~00 [crack]" (possibly 100)
"1A" or "10" [crack] unreadable character or two"

Going by Tayfun's Schematic, it should be a 100ohm resistor, looking through the threads some say its a 100ohm, 50W. I tried searching for a replacement, but I could only find 100ohm/50W resistors that tend to be ~4" long, this one is 2.00"-2.050" OAL and ~.600 OD

QUESTION-

Does anyone know the spec for a replacement resistor? would a 100ohm/25W-50W (seems to be the correct dimensions for the one that was in there) work without burning out?

Any guesses to what caused the resistor to self-destruct and the breaker to pop? I thought it may have been caused by feedback and failure of the Regen circuit, though I would think that much of an energy dump would have fried a lot more.

Due to the move, I can't afford a replacement Vector Drive, nor a Refurbished unit. If I can get a replacement resistor, then go through step-by step, probing as I reconnect it, I'm hoping I can get my machine back up and running, so i can finish some work and then buy a replacement/backup.

Thanks,

-John

You could try Digikey, they usually have a good selection, But I doubt the resistor is the problem, Just the symptom of something else fairly severe.
Al.

Dumb question does it still measure 100 ohm? if it does, it is not the problem. It still need to be replaced for long term operation..

Quote:

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Originally Posted by SteveWill

Dumb question does it still measure 100 ohm? if it does, it is not the problem. It still need to be replaced for long term operation..

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It may measure 100ohms, but since its broken in half, I'm not able to measure it.

Some time they will crack and the wire will not be broken.
That physical size is most likely a 25 watt, you can get the 50 watt and wire it to the board if you have room. it will not hurt anything.

Quote:

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Originally Posted by SEA_INC

I recently moved my shop to a new location, during the move my SL20 shifted on the truck. Though no damage was apparent at the time, we got it set up in the shop, leveled, wired, phase checked, spindle, turret, and tailstock alignment checked, everything was within spec, though the spindle centerline offset changed by ~0.015".

We ran some test pieces, and it cut to spec.

I had maybe 10 hours on the machine since the move, and had just finished a boring operation, as the turret was returning to G28, and the spindle was slowing from ~2,200RPM (G96) we heard a BANG! and the machine shut off.

I could see the 50A breaker on the wall had tripped.

I opened the back panel and looked for melted wires or anything burnt. Though I could smell the faint aroma of magic smoke, I couldn't locate the source.

I carefully worked my way from the breaker to the Vector Drive, checking voltages, it was the normal 209 - 210.5, and 230 off the transformer tap going to the Vector Drive. Though both the Phase Pass and Phase Fail indicator were lit.

I shut down the power and rechecked all the connections, everything looked good. So I powered it up again. The Phase Fail indicator went out.

I probed the DC BUS and it read 0.0V.

I checked the Alarms, and came up with:

903 CNC MACHINE POWERED UP

160 LOW VOLTAGE

123 SPINDLE DRIVE FAULT

I cleared the alarms, and only ALARM 123 SPINDLE DRIVE FAULT came back immediately, even after multiple resets.

I checked the Vector Drive and the POWER ON and FAULT LEDs were lit, the HIGH VOLTAGE was NOT lit.

I powered everything down, ate lunch, and then disconnected the Servo Drives from the DC BUS, powered it back up, and this time the POWER ON, FAULT, and HIGH VOLTAGE LEDs let up, though the HV was dim.

I probed the DC BUS and it read 18.0V, checked the DIAG page, and it concurred.

I powered it down, waited for the HV LED to go out, then disconnected the VD, I ran resistance/diode tests on the Spindle motor, Servo Drives, and Regen coils, everything seemed to be in spec.

I pulled the VD and threw it on the bench, pulled the cover, and started looking around.

I couldn't find anything burnt, melted, or visibly damaged, except for the off-board resistor that runs between the +HVDC on one of the MG150J2YS50 IGBTs and port J5 on the top board (which looks like it feeds Q4, a G7N60C.

The tubular ceramic resistor doesn't look burned, but it did melt the epoxy near the middle, and cracked the ceramic cleanly. I can't read the numbers except:

"~00 [crack]" (possibly 100)
"1A" or "10" [crack] unreadable character or two"

Going by Tayfun's Schematic, it should be a 100ohm resistor, looking through the threads some say its a 100ohm, 50W. I tried searching for a replacement, but I could only find 100ohm/50W resistors that tend to be ~4" long, this one is 2.00"-2.050" OAL and ~.600 OD

QUESTION-

Does anyone know the spec for a replacement resistor? would a 100ohm/25W-50W (seems to be the correct dimensions for the one that was in there) work without burning out?

Any guesses to what caused the resistor to self-destruct and the breaker to pop? I thought it may have been caused by feedback and failure of the Regen circuit, though I would think that much of an energy dump would have fried a lot more.

Due to the move, I can't afford a replacement Vector Drive, nor a Refurbished unit. If I can get a replacement resistor, then go through step-by step, probing as I reconnect it, I'm hoping I can get my machine back up and running, so i can finish some work and then buy a replacement/backup.

Thanks,

-John

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Have you found what resistor type this is mine had just blown! Need help asap! Thanks in advance!

Hi,
that looks very much like a in-rush current limit resistor, and in which case the exact value is not important. I have used as little a 20Ohm, which was and is quite common on Lincoln welder
in-rush circuits through to 200 Ohm which is common on ESAB inrush circuits.

All tend to be wirewound but I always preferred and had much better results with vitreous enamel coated resistors. Typically the in-rush current would, if continuous, hopelessly over power the resistor,
with continuous power levels of a kW or more. The resistors survive only by virtue of the fact that they are only energised for a few tens of milliseconds at power-up, and therefore never get hot enough
to destroy themselves in that short a period of time. Vitreous enamel coated resistors seemed better capable of long service in the face of the brief, but very serious, overload.

Once the in-rush has occurred, say ten milliseconds, then the resistor will be by-passed with either a relay or maybe a continously triggered SCR. Once the resistor is bypassed it no longer conducts current
and therefor no longer gets hot. If the by-pass fails for whatever reason then the in-rush resistor WILL be required to conduct full load current of the device, a welder, or in your case a vector drive, and its life
will be measured in seconds before it ends as your one has.

While it might be a ten dollar resistor which has failed, the cause could very easily be the by-pass circuit failing to operate, and the resistor is just the weakest link. El-cheapo Chinese made welders
use cheap by-pass relays, and the by-pass contacts would fail and the in-rush resistor would pay the price. I have seen and repaired such faults dozens, if not hundreds of times. For
seven years or so I worked as a repair technician for welding equipment. VFDs, servo drives etc have the same input architecture.

Craig

Quote:

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Originally Posted by Adamsmetalshop

Have you found what resistor type this is mine had just blown! Need help asap! Thanks in advance!

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I ended up having the Vector Drive repaired by a 3rd party. It also took out the servo Amp.

-John (SEA_INC)

Quote:

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Originally Posted by joeavaerage

Hi,
that looks very much like a in-rush current limit resistor, and in which case the exact value is not important. I have used as little a 20Ohm, which was and is quite common on Lincoln welder
in-rush circuits through to 200 Ohm which is common on ESAB inrush circuits.

All tend to be wirewound but I always preferred and had much better results with vitreous enamel coated resistors. Typically the in-rush current would, if continuous, hopelessly over power the resistor,
with continuous power levels of a kW or more. The resistors survive only by virtue of the fact that they are only energised for a few tens of milliseconds at power-up, and therefore never get hot enough
to destroy themselves in that short a period of time. Vitreous enamel coated resistors seemed better capable of long service in the face of the brief, but very serious, overload.

Once the in-rush has occurred, say ten milliseconds, then the resistor will be by-passed with either a relay or maybe a continously triggered SCR. Once the resistor is bypassed it no longer conducts current
and therefor no longer gets hot. If the by-pass fails for whatever reason then the in-rush resistor WILL be required to conduct full load current of the device, a welder, or in your case a vector drive, and its life
will be measured in seconds before it ends as your one has.

While it might be a ten dollar resistor which has failed, the cause could very easily be the by-pass circuit failing to operate, and the resistor is just the weakest link. El-cheapo Chinese made welders
use cheap by-pass relays, and the by-pass contacts would fail and the in-rush resistor would pay the price. I have seen and repaired such faults dozens, if not hundreds of times. For
seven years or so I worked as a repair technician for welding equipment. VFDs, servo drives etc have the same input architecture.

Craig

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Thanks for the response.

I ended up having the Vector Drive repaired by a 3rd party, along with the servo amplifier. The updated servo Amp has a fuse, which the original design lacked.