Spindle acceleration and deceleration issues on VQC 250/50B
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    Question Spindle acceleration and deceleration issues on VQC 250/50B

    Hi all,

    its time for consultation with all ye wise folk what may have encountered my problem and can guide me in my quest for inner peace (and stop me going out of my mind )…..

    The other day I was milling on the VQC 20/50B and had a minor crash when a job pulled out of the 3 jaw chuck I had mounted to the table. It broke the 12mm cutter but nothing overly horrendous...


    Anyway, after resuming, the spindle ramp up time seemed to take a significant while compared to usual...up around the 10 second mark... and ramp down from 3000rpm is taking longer than 12 seconds and I receive an error 251 (spindle controller malf. which is linked to >500rpm difference to setpoint for longer than 12 seconds).

    I can ramp up and down with the arrow buttons and it tends to keep up ok, but when I do a spindle start or spindle stop from the upper rpm range, I have issues like the motor isn't slowing down fast enough.(I can regenerate the issue every time)

    The orient is also hunting when chasing the final positioning (never happened before but feel this is linked to the motor control circuit.)

    At first I thought I may have sheared the key between the motor and the gearbox... Inspected that and it is in pristine condition, as is the gearbox itself..

    The literature suggests the motor feedback encoder (PLG) could be the issue so I have tested this also with an oscilloscope (and inspected and gapped the sensor), and while there was a little bit of noise when observed at the motor, the signal at the controller was nice and clear. The amplitude was in the order of 4V (recommended to be 3V, but not sure that this is causing any issues as it is still seeing the pulses in manual.)

    It appears that the motor accel and braking isn't getting the right amount of indication/ power to slow down/ accelerate appropriately...

    I also checked a number of other things the manuals suggested but haven't found anything out of the ordinary as yet and am at a bit of a loss. (I monitored the drive voltage on ramp up and ramp down and it is above the minimum 180V - was above 200v, also checked the sine waves on the feedback PLG and signal from the spindle encoder at various rpms and no obvious issues there, checked the motor resistance, along with any phase grounding issues and all was fine also..)


    There are no errors coming up (other than the 12 second lag issue) but its starting to sound like a card issue in the drive controller (FR-SE).


    Has anyone had any similar experiences that could point me in a direction to prove the actual problem before I blow a hole in the budget chasing replacement cards?

    Any thoughts/ comments/ suggestions/ WAGs (Wild Arse Guesses) are much appreciated at this point.

    Cheers

    Mick

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    Quote Originally Posted by sophtayl View Post
    Hi all,

    its time for consultation with all ye wise folk what may have encountered my problem and can guide me in my quest for inner peace (and stop me going out of my mind )…..

    The other day I was milling on the VQC 20/50B and had a minor crash when a job pulled out of the 3 jaw chuck I had mounted to the table. It broke the 12mm cutter but nothing overly horrendous...


    Anyway, after resuming, the spindle ramp up time seemed to take a significant while compared to usual...up around the 10 second mark... and ramp down from 3000rpm is taking longer than 12 seconds and I receive an error 251 (spindle controller malf. which is linked to >500rpm difference to setpoint for longer than 12 seconds).

    I can ramp up and down with the arrow buttons and it tends to keep up ok, but when I do a spindle start or spindle stop from the upper rpm range, I have issues like the motor isn't slowing down fast enough.(I can regenerate the issue every time)

    The orient is also hunting when chasing the final positioning (never happened before but feel this is linked to the motor control circuit.)

    At first I thought I may have sheared the key between the motor and the gearbox... Inspected that and it is in pristine condition, as is the gearbox itself..

    The literature suggests the motor feedback encoder (PLG) could be the issue so I have tested this also with an oscilloscope (and inspected and gapped the sensor), and while there was a little bit of noise when observed at the motor, the signal at the controller was nice and clear. The amplitude was in the order of 4V (recommended to be 3V, but not sure that this is causing any issues as it is still seeing the pulses in manual.)

    It appears that the motor accel and braking isn't getting the right amount of indication/ power to slow down/ accelerate appropriately...

    I also checked a number of other things the manuals suggested but haven't found anything out of the ordinary as yet and am at a bit of a loss. (I monitored the drive voltage on ramp up and ramp down and it is above the minimum 180V - was above 200v, also checked the sine waves on the feedback PLG and signal from the spindle encoder at various rpms and no obvious issues there, checked the motor resistance, along with any phase grounding issues and all was fine also..)


    There are no errors coming up (other than the 12 second lag issue) but its starting to sound like a card issue in the drive controller (FR-SE).


    Has anyone had any similar experiences that could point me in a direction to prove the actual problem before I blow a hole in the budget chasing replacement cards?

    Any thoughts/ comments/ suggestions/ WAGs (Wild Arse Guesses) are much appreciated at this point.

    Cheers

    Mick
    those FR-SE are very old bastards. I seen a problem on QT machine when spindle wasnt accelerating fast enough and was alarming with same alarm. Sort of too long to get up to the set point. The guy checked PLG amp, adjusted, no positive result. At the end of the day, on FR-SE amplifier, second board ( which is IO board) had problems with power transistors drivers. Two of them had bad output voltage span, I would assume, they didnt fully open power transistors while working. Board was changed, problem is gone.

    p.S for sp. orientation to be properly done, Z phaze output must be good, not just A anb B ( -/+1.5 DCV) , that Z is either separate channel or, like someone told us, separate magnet located somewhere else.

    p.s.s how about that, when you crashed it, spindle stopped or slowed down very quickly and inside FR-SE, amount of energy coming from AC motor, couldnt escape properly trough regeneration circuit. That could cause a damage to electrical parts, just the thought

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    Ok so I did some more digging based on Nonames comments and some discussion with Sudsy...

    I have carried out the Base unit checks as per the test procedure and have some anomalies -

    (https://us.mitsubishielectric.com/fa...WH3ZZR-24-3382)


    VI) colour of indicator on top of Big caps - mine are white- I don't know if that is healthy or damaged.

    XIII) Diode Stack resistance - my numbers were all lower than the test stand values (Approx 30%)

    XIV) Outputs of Converter - my numbers were all lower than the test stand values (Approx 30%)

    XVI) Outputs of Inverter - my numbers were all lower than the test stand values (Approx.30%)

    XVII) Inputs of Converter - my numbers were all higher (except 2)than the test stand values
    (varied up to double)

    XVIII) Inputs of Inverter - my numbers were all lower than the test stand values by a factor of 1000 (Im hoping there is a typo in the document)

    Below is what I see on both Capacitor indicators- not sure if these are clear or expired.. will need to pull them out to check unless someone can advise based on the indicator?

    capacitor-pic-4.jpg

    I also captured some waveforms for more info..

    This is the PLG signal at the controller

    plg-signal.jpg

    The shape looks ok but the voltage Peak to Peak was showing 3.5-5V due to the noise..


    The converter and inverter waveforms also had some anomalies.


    One converter channel had no cycling waveform (flat line)
    converter-typical-waveform.jpg

    converter-abnormal-waveform-ch-50.jpg

    Two inverter channels looked to have inverted wave forms compared to the others
    inverter-abnormal-waveform-ch-45-ch-46.jpg

    I also measured the resistance from the respective channels across the transistors to the resistor as per some recommendations I found on some forums to identify faulty transistors circuits, but these all came up the same and as per recommended values. I'm hoping the issue lies in the base unit hardware if I can confirm whether the results I have are as expected or if they are out of whack.

    Will need to follow up a replacement IO1 board I expect but want to be sure before dropping excessive coin..

    Has anyone run these tests/ have data/ able to carry out the base unit tests to compare?

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    Default Spindle acceleration and deceleration issues on VQC 250/50B

    Some points to check:

    1.) Make sure your SE-PW power supply is putting out correct voltages on all the pins.

    2.) Look over your SE-IO1 main board real close. The DK434 hydrid chips are the drivers for the base transistors, and are known to fail. I have used comparative measurements with ohm meter to distinguish a bad one --- or some skill with an oscilloscope can determine bad ones as well.

    If replacing the DK's (source on EBay) aways replace the adjacent transistor, caps, and diode(s) to be safe.

    3.) The original base transistors are a known failure point as well. Sometimes you have to take them out of circuit to find one or more bad ones.

    You can source replacements on EBay.
    As long the new blocks have similar or higher voltage and amperage ratings, they should work fine.

    Actually the original blocks are an older type called Darlington transistors. I replace them with the more modern, more robust, true IGBT's.

    A Google search for data sheets can verify which is which....

    4.) Replacing the FR-SE with a new drive isn't all that complicated (or expensive)...a couple members here on PM have done it.

    Good luck with it!

    ToolCat

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    I have a spare working FR-SE but I am un the other side of the world

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    Quote Originally Posted by benganboll View Post
    I have a spare working FR-SE but I am un the other side of the world
    Benganboll

    Lets not rule that out just yet.

    Will do a bit more digging to see if I can pinpoint things

    Sent from my SM-G930F using Tapatalk

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    Quote Originally Posted by cnctoolcat View Post
    Some points to check:

    1.) Make sure your SE-PW power supply is putting out correct voltages on all the pins.

    2.) Look over your SE-IO1 main board real close. The DK434 hydrid chips are the drivers for the base transistors, and are known to fail. I have used comparative measurements with ohm meter to distinguish a bad one --- or some skill with an oscilloscope can determine bad ones as well.

    If replacing the DK's (source on EBay) aways replace the adjacent transistor, caps, and diode(s) to be safe.

    3.) The original base transistors are a known failure point as well. Sometimes you have to take them out of circuit to find one or more bad ones.

    You can source replacements on EBay.
    As long the new blocks have similar or higher voltage and amperage ratings, they should work fine.

    Actually the original blocks are an older type called Darlington transistors. I replace them with the more modern, more robust, true IGBT's.

    A Google search for data sheets can verify which is which....

    4.) Replacing the FR-SE with a new drive isn't all that complicated (or expensive)...a couple members here on PM have done it.

    Good luck with it!

    ToolCat
    I ran some more checks today to confirm yesterdays results.


    One converter channel had no alternating waveform ( Ch50)

    two inverter channels had oblique forms ( as per the pic).


    I also checked the resistance across each invertor/ convert phase block (from channel pin to resistor) and all 12 had the same resistance. between 2.17 and 2.2 Kohms.

    I also checked the transistors in situ and all appear to be working as intended. I will probably have to drop them out to check them independently.

    I ran the meter along the pins of the DK434 and there did not appear to be any anomalies between the DK434 drivers.. Im hunting down a data sheet to confirm the circuit in the dk434 to see if what I am checking is correct or leading me up a garden path.

    I ran the check from the power supply to each inverter/ converter channel and were all at 3.3V except for 2 which were about 4.1V. I will check the terminals for the 8v tomorrow... (before I do any desoldering)

    If all of the above checks out ok, what is there that provides the alternating wave form? maybe this is the problem with Ch50?

    I'm not too clued up on the circuitry but working my way through it..

    Cheers

    Mick

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    Quote Originally Posted by sophtayl View Post
    I ran some more checks today to confirm yesterdays results.


    One converter channel had no alternating waveform ( Ch50)

    two inverter channels had oblique forms ( as per the pic).


    I also checked the resistance across each invertor/ convert phase block (from channel pin to resistor) and all 12 had the same resistance. between 2.17 and 2.2 Kohms.

    I also checked the transistors in situ and all appear to be working as intended. I will probably have to drop them out to check them independently.

    I ran the meter along the pins of the DK434 and there did not appear to be any anomalies between the DK434 drivers.. Im hunting down a data sheet to confirm the circuit in the dk434 to see if what I am checking is correct or leading me up a garden path.

    I ran the check from the power supply to each inverter/ converter channel and were all at 3.3V except for 2 which were about 4.1V. I will check the terminals for the 8v tomorrow... (before I do any desoldering)

    If all of the above checks out ok, what is there that provides the alternating wave form? maybe this is the problem with Ch50?

    I'm not too clued up on the circuitry but working my way through it..

    Cheers

    Mick
    You cant describe signals like having anomalies. Those inverter/ convertor signals have shape, positive part, negative part, period , duty cycle, falling age and rising age. Very important to have good falling age, as whole FR-SE output part is 3 phase full-bridge circuit. if falling age has a tail, then transistor wont be able to close itself fast enough or will open itself twice. In that case top transistor will put current straight through bottom one( I am talking about singe IGBT unit) and not trough motor winding and diagonal IGBT ( full-bridge ). And here is game is over. Huge inrush current basically in millisec. destroys internal components of IGBT.

    Can you send it somewhere for repair?

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    Quote Originally Posted by noname777 View Post
    You cant describe signals like having anomalies. Those inverter/ convertor signals have shape, positive part, negative part, period , duty cycle, falling age and rising age. Very important to have good falling age, as whole FR-SE output part is 3 phase full-bridge circuit. if falling age has a tail, then transistor wont be able to close itself fast enough or will open itself twice. In that case top transistor will put current straight through bottom one( I am talking about singe IGBT unit) and not trough motor winding and diagonal IGBT ( full-bridge ). And here is game is over. Huge inrush current basically in millisec. destroys internal components of IGBT.

    Can you send it somewhere for repair?
    Im waiting on some feedback from John Hart re a replacement.

    Is the flutter in the wave an issue ?

    Also this is the signal without a good wave on 2 channels (seem to drop off)


    And the 3rd is one on channel 50 with a flat line..

    The final image is what I am getting on the others.

    I also pulled the power supply open and have 2 large caps the looked cactus. Measured across them out of circuit and get some small nF readings for a 220uF cap. Have ordered a couple to replace them. Would these be creating the issues?


    Sent from my SM-G930F using Tapatalk

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    Ok just got a quote for the replacement card. At over rhe value of a kidney replacement, does anyone recommend someone in Australia that can look at the card for me?

    Sent from my SM-G930F using Tapatalk

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    all is fixable. you will do it. no drama so far, as long as IGBT are alive

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    Quote Originally Posted by noname777 View Post
    all is fixable. you will do it. no drama so far, as long as IGBT are alive
    I've called a guy to come and have a look. Seemed quite familiar with the controller (recommended from another cnc repair company as he specialises in japanese machines). Hopefully can save me some time. Hoping he can be here on friday.

    In the meantime new caps for power unit should arrive in next vouple of days so hopefully they will be installed before he gets here so he can test accordingly.

    So im back on the manual machines to get a job out the door


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    change all capacitors. All. At Jay Car it will cost you to buy them around 100 aud. But to change them is another story

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    still waiting on caps for Power unit (had the 2 big ones on order). I put the old ones back in with the hopes that I could get power on the machine for when the tech guys turns up.

    It now appears I also have a power unit issue - no amber light and wave forms are all flatline. the IO1 board green lights come up, but there is no Power out of the terminals from the power pack . (hopefully this will get rectified with replacement caps. I will chase up all the additional caps and change them while I am at it).

    so for now I have deferred the visit till I get the power unit back to life..

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    Don't forget about EBay for spare parts, I've had lots of good luck buying there...

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