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  1. #11
    Quote Originally Posted by Doddy View Post
    (there's a chance of a fault on the spindle board dragging the analogue output from the BOB down - this just helps to isolate the problem).
    This is why I said to disconnect the BOB from the spindle board when checking volatge so hopefully Ken did this.?

    Also I'm not sure which Spindle board it's using but I know a lot of these spindle boards have mains voltage kicking around the Analog input so be careful Ken.!

  2. #12
    Thanks everyone for the comments. I have since put a question on CNC4PC forum and I await comments. It's looking very like the BOB. I'll post the result as it might be of interest to someone else.
    Ken

  3. #13
    Hi Folks
    Still chasing the problem of having no spindle. I've been working with Aturo at cnc4pc but have had little sucess. The only board that hasn't been replaced is the small AP2 board which lies between the BOB and the main motor board. All the necessary voltages are now coming out of the new BOB to the connections at the board. Does anyone know what this sall board does and if outputs can be tested? Getting new AP2 board being hampered by present world situation.

    Thanks
    Ken

  4. #14
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 9 Hours Ago Has been a member for 6-7 years. Has a total post count of 805. Received thanks 129 times, giving thanks to others 34 times. Referred 1 members to the community.
    Okay, I've spent 20 minutes too long trying to find out what the AP2 is, and failed. There's various talks of step/dir controls on the KX3 but I'm minded not to read too much into that at this time. Can you get a photo of the board to perhaps help us understand it better?

  5. #15
    Hi Doddy
    Thanks for your prompt reply. Here is a photo ofthe suspect AP2.Click image for larger version. 

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    Hope this works.
    Thanks
    Ken

  6. #16
    I think it is the speed control board, does it have a potentiometer on it.? I think the AP stands for Analog Potentiometer Board.

  7. #17
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 9 Hours Ago Has been a member for 6-7 years. Has a total post count of 805. Received thanks 129 times, giving thanks to others 34 times. Referred 1 members to the community.
    Ugh. I wish I'd never asked, now. I'm throwing an awful, awful lot of guesswork into this that might be completely misleading.

    Have you seen this link and does it look sensible and appropriate?

    https://littlemachineshop.com/images...UpgradeKit.pdf

    If only for the association with the board. I'm reading more, and this is hitting the territory I'm in with spindle speed control on a SX2.7. But, my interest lies if this is OEM or a modification to the KX3

    EDIT: Though read somewhere that Sieg used these boards themselves for the CNC machines.

    I'm out of ideas here - there's clearly two opto-couplers that are connected to the spindle-control board - these could be step/dir but that's guesswork. I would expect that these would be involved with the speed control given the nature of this board - if you had access to a scope it would fall into the "interesting" category of investigation, but you're looking at a fairly proprietary interface now between this and the BLDC controller in the Seig.

    But you've convinced yourself that your analogue wiring to the board is correct?

    EDIT 2: I'd check through that link and verify your wiring as a first port of call.

    My experience of the BLDC board is that can be fragile (mine popped two IGBT and a fair bit of collateral circuitry early in its life - replaced under warranty), and you've suggested that you may have had similar problems and replaced the board yourself in the past. So there's a question that you have no spindle control (no rotation)... is it the BoB - you suggest not / this is replaced. Is it this board or the spindle board (BLDC controller) - and that can be a challenge to understand (sorry, that's not very helpful I know)
    Last edited by Doddy; 06-04-2020 at 02:36 PM.

  8. #18
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 9 Hours Ago Has been a member for 6-7 years. Has a total post count of 805. Received thanks 129 times, giving thanks to others 34 times. Referred 1 members to the community.
    Anecdotal footnote: When I get around to it I'm tempted to replace the whole Sieg board with a Chinese BLDC controller - they appear quite reasonable in cost, and offer 0-10V speed control out of the box. I did start looking at the start of this enforced isolation business but got distracted. I may pick up on this again.

  9. #19
    Quote Originally Posted by JAZZCNC View Post
    I think it is the speed control board, does it have a potentiometer on it.? I think the AP stands for Analog Potentiometer Board.
    The blue thing, top right hand corner of the photo is a trimmer potentiometer, possibly a multi-turn type. The label under it looks like "START/STOP". If you adjust it keep track of how many turns and in which direction so you can put it back where it was.

    Edit: Just made time to read Doddy's link. START/STOP is a label on one of the connectors. The potentiometer is for the speed at max control voltage. Pots can become faulty and go high resistance but it's possible to clean the track inside by simply adjusting it up and down a few times. Certainly worth a try for the time it takes.
    Last edited by Kitwn; 07-04-2020 at 08:59 AM.
    Engineering is the art of doing for ten shillings what any fool can do for a pound.
    Wellington.

  10. #20
    That board looks exactly like little machine shops upgrade board.
    Was the machine bought new by you are did you buy it used? Might be the LMS board in there already. Straight swap.

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