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  1. #1
    Join Date
    Jun 2012
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    30

    SOS - Interact 1 Mk2 blowing fuses

    Hi,

    Earlier this evening, my Interact 1 Mk2 suddenly stopped mid-program, for no readily apparent reason. Investigations showed that fuse MF1 had blown. In the hope that this was just a flaky fuse, I swapped it out, and gingerly powered up; so far so good; but when I pushed the orange "go" button. Pressing the green "GO" button correctly started the spindle blower, and E-stop stopped it again. Didn't try the "spindle off" button.

    Poking around in the cabinets I found a tripped trip. Reset that, powered up again, pressed orange button "clack" - dead again, same symptoms, blown MF1.

    This machine has had a very noisy Z-axis choke, but I'm not sure that's the problem (why would it consistently blow phase L1?), could it be the autotransformer that's failed?

    Unfortunately, the troubleshooting guide is silent on the causes of blown fuses, and I can't get any more now until tomorrow.

    If anyone has any suggestions as to what I should check & how (I'm handy enough with a multimeter), I would be most grateful.

    Cheers!
    Ade.

  2. #2
    Join Date
    Mar 2007
    Posts
    2083
    Hi Ade

    do you have a link to the manual or the circuit diagram showing the connections to the auto transformer and the choke

    also which switch is the orange button - power on to auto transformer and the 3 axis drives ?

    it would be easier with a "Megger" to test the insulation at 250 or 500V DC

    but you could try it with the spindle motor disconnected

    If the fuse still blows swop the connections to the transformer input ( assuming they are connected to L1 and L2 )

    you could find one end of a primary is leaky to earth


    John

  3. #3
    Join Date
    Jun 2012
    Posts
    30
    Hi John, thanks for the speedy reply

    Yes, the orange button is the one that enables the axis motors (and therefore the autotransformer & chokes). It should have a light in it, but that has not worked since I bought the machine...

    I don't have a link to the wiring diagram, I've got a paper copy (annoyingly soaked in oil) that came with the machine, and a copy which came with the service manual, I bought that one off eBay. I haven't yet tried tracing the wires out of the fuse, I guess that's the next trick.

    Wish I hadn't sold my duplicate machine now

  4. #4
    Join Date
    Mar 2007
    Posts
    2083
    Hi Ade ,

    that's the way it goes , keep some thing for years and need it the week after you dispose of it

    I've found 2 halves of the circuit diagram in another post and pasted them together

    with the power off your multimeter may not show any leakage between the 0V / L1 terminal and earth

    I'd disconnect the the two mains supply wires (L1 & L2) from the auto transformer
    and then use a 15W pigmy lamp / GLS bulb to connect one phase to the transformer 0V terminal

    depending on the leakage ,the bulb may light other wise you may be able to measure a AC voltage across the bulb terminals

    my first suspects would be the auto transformer , one of the drivers , a motor and a choke

    John

    Click image for larger version. 

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    PS

    to avoid having to wind a transformer
    I've been thinking a xenon flash circuit from a disposable camera could be adapted
    to make a simple insulation tester


    Attachment 194034

    Click image for larger version. 

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  5. #5
    Join Date
    Jun 2012
    Posts
    30
    Hi John,

    I _think_ it's the autotransformer... with the aid of a bag of fuses & some luck, I traced the fault to the 20v line off the autotransformer. If I disconnect that one & leave everything else on, the machine works (sort of). I got power to the axis drives. Z passed its reference mark OK. Y did eventually, but it was a bit slow about it & stopped 2-3 times; when X started it was crawling along; it would have taken a good 10 mins to get to the reference...

    So, does that mean my autotransformer is suspect #1? I didn't let it complete referencing, it seemed to be struggling; plus I'm not sure what's fed from the 20v supply that might be important... according to the book, nothing is hooked to 20v


    Does anyone know any companies in the UK who break machines for parts? I'm guessing the price of a brand new autotransformer would probably eclipse the price of the entire machine...

  6. #6
    Join Date
    Jun 2012
    Posts
    30
    OK... possibly not the autotransformer....

    When contactor 5FC pulls in, is it supposed to connect all 4 wires together? I'm seeing a dead short across this contactor, if the 20v line (wire 111) is connected. Disconnect that, and the machine powers up, but cannot position properly. Hook the wire back in = instant dead short, blown MF1 fuse...

    What I don't understand is, on the top 2 contacts of 5FC, I can see L1 & L2 on both contacts; so on the LH top contact we've got L1 @ 0ohms, and L2 @ ~9ohms. On the Left-Middle top contact there's L1 @ 9ohms & L2 @ 0ohms. - that's with the contactor off & obviously no power to the machine... so why aren't they shorting each other anyway? Surely 9ohms isn't much in the way of resistance?

    Unfortunately, my electronics knowledge is now not enough to proceed Can anyone help put me out of my misery??

  7. #7
    Join Date
    Mar 2007
    Posts
    2083
    Hi Ade

    the 4 wire should not be connected together when the contactor is energised , but with the DC resistance of the transformer windings being so low
    it will may look like they are, depending on the resistance range you have selected


    if you measure across the L1 and L2 supply wires to the contactor 5FC
    you will measure the resistance of transformer T1's primary unless you remove one of 10A fuses ( TFU1 or TFU2)

    measuring across the switched supply from the contactor 5FC terminals T1 & T2 (wires 111 & 112) you will measure auto transformer T2's "primary"

    when the contactor coil is energised terminals 1 & 2 (L1 and T1) are connected together and
    terminals 3 & 4 (L2 and T2) are connected together to power the auto transformer
    terminals 5 & 6 are used to latch the contactor on

    Attachment 194186

    Click image for larger version. 

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    Do you know what your 3 phase voltage is ?

    my single phase supply is 247 V
    so if I had a 3 phase supply I'd have root 3 x 247V = 1.732 x 247 = 428V
    and I would select the 20 + 420 V taps (440V)
    { mains L1 (wire 111) on the 20V tap & L2 (wire 112) on 420V}
    the 0V connections to the 3 servo drivers remain the same
    Attachment 194234


    If your supply is 420 V , the diagram showing the connections to the 0V and 420V taps is correct
    and as far as I can see you should not have any connection to the 20V tap
    mains L1 ( wire 111) is connected to the 0V tap & L2 (wire 112) is conected to the 420V tap
    Attachment 194236


    so the question is what was the 20V tap connected to ?

    a photo will help

    if the part of the winding between the 20V & 0V taps went open circuit at some time
    I can see someone would connect them both together and to the L1 supply)

    and you would now have 160V on wire 131 instead of 180v and every thing may work OK
    until the broken ends make contact again - short circuiting the 20V output
    resulting in shorted turns in the transformer

    Click image for larger version. 

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    I hope you can find another transformer as I expect having it rewound will be expensive
    the first result I found in liverpool is - Electric Motor Repairs | Electric Motor Rewinds | Armatures Liverpool
    another possibllity is finding a UK transformer manufacturer that rewinds them

    but I expect John Stevenson will know more



    John

    PS - link to transformer manufacturer that also rewinds them -

    http://www.vvttransformers.co.uk/rewinds.htm

  8. #8
    Join Date
    Jun 2012
    Posts
    30
    Hi John,

    Thanks for the detailed reply; the picture of the contactor doesn't look like the one that's blowing; it's next to the one pictured (to the left). There are 2 secondary contactors mounted on top of it.

    Unfortunately, I don't have a link to the diagrams, I'll get some scanning done this afternoon so you can see what I mean. I'll get a photo of the dodgy contactor too.

    Line 111 is connected to 20v on the autotransformer, and the bottom left contact of the contactor labelled 5FC on the board (also labelled 5FC on my wiring diagram, although the numbers are all but impossible to read). Not sure about 112, but looking at your 3rd diagram (with 111 on 20v & 112 on 420v) looks right, if my memory doesn't deceive me.

    Anyway, I'll get some pictures & diagrams up in a couple of hours or so, when I can get down to the shop.


    Cheers,
    Ade.

  9. #9
    Join Date
    Jun 2012
    Posts
    30
    Tried - and failed - to get the scanner working, so it's photos only I'm afraid.

    Attachment 194288

    The contactor in question is bang in the middle; the one you drew is to the right (and has nothing connected underneath it); the overload trip is to the left.

    Cable 111 comes in underneath to the left-most terminal (under the "K2" that you can just make out).

    L1 is attached to the top left contact, L2 the next one along. There's a 3rd set of contacts visible, behind the 2 auxiliary contactors which are mounted in front of the main contactor. The spark is in this region when powering up.

  10. #10
    Join Date
    Mar 2007
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    2083
    Hi Ade

    having looked at the picture , I think I've found all of the connections to the 5FC contactor on the circuit diagram ( marked in red )

    Click image for larger version. 

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    the contactor has a 110V AC coil powered by transformer T1

    two high current pairs of contacts to switch the supply to the auto transformer

    and 4 pairs of auxilary contacts for the control functions ( 3 N/O and a N/C )

    1 N/O aux pair is a high current pair numbered 5 & 6 used the hold in the contactor

    N/O pair 13 & 14 powers the power enable lamp 2 and the spindle solenoid

    the 2 extra add on auxilary contacts are-

    N/O pair 43 & 44 signals the TNC input J1/9

    N/C pair of contacts 21 & 22 appears not to be used - terminal 77 is not connected to the TNC unit


    Attachment 194424


    as far as I can tell contactor terminals are numbered following this sequence -
    N/O high current pairs are numbered 1 & 2 , 3 & 4 , 5 & 6
    N/O aux pairs are numbered 13 & 14 , 23 & 24 , 33 & 34 etc
    N/C aux pair are numbered 11 & 12 , 21& 22 , 31 & 32 etc
    and the coil A1 & A2



    John

  11. #11
    Join Date
    Nov 2006
    Posts
    925
    I think MF1 also feeds the transformer for the axis drives and I'd be inclined to disconnect that feed and replace the fuse and see if it still blows.

  12. #12
    Join Date
    Jun 2012
    Posts
    30
    It was a blown X-axis motor...

    Thanks to John_100 who came over to my shop, we spent a happy half hour (er, or 4) poking around in the oil and swarf, and eventually determined the X-axis motor was the faulty one. Disconnecting just that motor allows the machine to behave normally.

    Luckily, I've sourced a motor (this time), albeit at significant cost... now looking at an identical machine on eBay for £3k & wondering if it's worth that in spares alone...

  13. #13
    Join Date
    Mar 2007
    Posts
    2083
    It was a good afternoon meeting Ade and seeing his machine
    I think it was ½ hour fault finding and 4 Hour talking about all sorts

    the mill was a lot more pleasant to work on than the EMI-MEC Sprint capstan lathes
    I've repaired in the past -
    not related to my day job and usually covered in brass swarf and oil

    the problem was finding it needed an expensive spare part to fix it
    the motor has a low resistance between the armature connections and the earthed body


    John

  14. #14
    Join Date
    Dec 2003
    Posts
    24216
    Quote Originally Posted by john_100 View Post
    the motor has a low resistance between the armature connections and the earthed body


    John
    With brushed motors, most of the time that kind of fault is the brush gear going to ground because of carbon tracking?
    If the com is still good, it can often be repaired by re-insulating the brush holder etc, cleaning all the carbon and replacing the brushes.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  15. #15
    Join Date
    Jun 2012
    Posts
    30
    Hi Al,

    You may be right, although the brushes seem to have loads of life left in them (good 3/4" of carbon left) - of course, I don't know if the brushes have been replaced in the past... We did try blowing the carbon out with compressed air, but other than a nasty "magic smoke" smell, there was no evidence of excessive carbon. Although, after blowing out & replacing, the motor did run for a few seconds before it blew the fuse again.


    When I spoke to a motor rewind company, he said "bring it in" (for a quote), but don't split the tacho from the motor... I presume there is a good reason for this & therefore, if I were to open the motor up to attempt a cleanout & repair, is there anything I need to watch out for? Or, having never done anything like that before - and with a history of permanantly destroying electronic kit due to hamfistedness, should I leave well alone?


    Anyway - new motor arrived from the US today, plugged it all in & off she went, good as new. Much less noisy too, so I think the old motor was running on luck for quite a while...

  16. #16
    Join Date
    Mar 2007
    Posts
    2083
    Hi Ade

    that was Quick and good result

    now you can finish off the sump and take your time with the old motor

    John

  17. #17

    Re: SOS - Interact 1 Mk2 blowing fuses

    [QUOTE=AdeV;1325752]It was a blown X-axis motor...

    Thanks to John_100 who came over to my shop, we spent a happy half hour (er, or 4) poking around in the oil and swarf, and eventually determined the X-axis motor was the faulty one. Disconnecting just that motor allows the machine to behave normally.

    Luckily, I've sourced a motor (this time), albeit at significant cost... now looking at an identical machine on eBay for

  18. #18
    Join Date
    Jun 2012
    Posts
    30

    Re: SOS - Interact 1 Mk2 blowing fuses

    Quote Originally Posted by jack-pat View Post
    Hi Ade,

    I have read through this thread and i believe my machine has the same fault, could you tell me how to disconnect the x-axis? It was making some strange noises this morning (only the x-axis motor) and it has been blowing the fuse in MF1. Help would be much obliged as i only have one fuse left :S
    Hi Jack,

    I'm assuming you have the black SEM motors, with a box about 2.5" x 1.5" x 3/4" located towards the rear of the motor.

    Obviously the first job is to disconnect the power supply, or make sure you're properly isolated & that no-one can switch on whilst you're in the bowels of the machine.

    The first job is to remove the tinwork from around the motor; this isn't vital, but it gives you better access to the wiring box.

    Next up, remove the 4 screws on the electrical box. They're quite long, and will be fiddly as hell to replace. When the last one comes loose, the lid & body of the box should both come away from the motor. Remove the lid & rubber gasket, noting the orientation for re-assembly (not vital, but the indents will make it go together easier the right way than the wrong way).

    Moving the box body out of the way should reveal a terminal block with about 6 wires connected. These will either be of distinct colours, or will have number rings attached. IIRC 4 are fat & 2 are thin. Ignore the thin wires. Make a note of the colours/numbers of the fat wires & their position in the terminal block. Unscrew & disconnect each wire, making it safe with some electrical tape.

    Now plug in and fire up the machine. You should be able to get to the point where it indexes in the X-axis position (which it can't do, because the X-axis won't drive.

    To remove the motor - go back & pull off the tinwork if you haven't already. You now need an 8mm allen key (IIRC - might be a 7), to undo the 4 bolts holding the motor in. The bolt heads are on the front of a metal plate, the motor is bolted to the back of this plate. You are looking at the back of it, so you have to get the allen key in by feel, then remember to turn it the right (wrong) way to loosen. Once all 4 are done, catch the motor before it hits the floor, and disentangle it from the drive belt.

    Re-assembly, once you've sourced a new motor, is the reverse of dissasembly (or so they say).

    HTH!

    Cheers,
    Ade.

  19. #19

    Re: SOS - Interact 1 Mk2 blowing fuses

    Thanks for the quick reply and detail!

    Disconnected the 4 thick wires from the motor, there was also two thin wires and two earths.. Turned machine on.. When i hit the "power up" button (not the cycle start button), relay 8CR clicks but nothing else happens, in other words it wont turn everything on so i cant index Y and Z.

    When everything is connected and i press the power up MF1 Blows, also i disconnected wires 5, then 6, then 7 from the long terminal strip at the left hand side of the cabinet and each time MF1 blows.

    Any other ideas?

    This is also my only mill so help really is much appreciated!

    MANY thanks,

    Jack

  20. #20
    Join Date
    Jun 2012
    Posts
    30

    Re: SOS - Interact 1 Mk2 blowing fuses

    Mine indexes in the order Z-Y-X, is that the same as yours? If so, with X disconnected, you should still be able to reference Z and Y.

    As far as I am aware - all axis motors are powered as soon as you press the orange "power up" button; so, if having disconnected the X-axis motor it doesn't blow the fuse (but equally, nothing happens), then there are 2 things to try:

    1) Remove X & Y motors & swap them - they should be the same spec. Leave Y axis motor disconnected & power up. You should now be able to reference "X", but no further.

    2) Remove X axis motor. Manually turn the drive belt to move the table towards its indexing point. Depending on where it is, this might be quite tedious... Now power up as before, and manually index the X-axis. Assuming that works (dunno if it will without a signal from the X-axis tacho), and the X-axis registeres, now register Y and Z.

    Either case, we're trying to prove that the X axis motor is the faulty one.

    Cheers,
    Ade.

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