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  1. #41
    Join Date
    Feb 2007
    Posts
    4550

    Re: Help me find a BOB !

    Quote Originally Posted by john-100 View Post
    for any one looking at the picture of the damaged board and wanting to know how to read the resistor values

    try this - Resistor color code calculator - 3, 4 and 5 band resistors

    Attachment 267184


    John
    John,

    You are 100 percent correct on the 1K resistors.

    It looks as if all three 100 ohm resistors are in parallel and connected to ground on the BOB. Total for the three resistors 33 ohms

    Jeff...
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  2. #42
    Join Date
    Feb 2007
    Posts
    4550

    Re: Help me find a BOB !

    I need to wake up, before I start typing.
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  3. #43
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi Jeff

    yes the 100 ohm resistors are in parallel

    one end of each resistor connected to the break out boards ground
    and the other ends connected to the 3 Gecko drives signal common terminals (12)
    they are in turn connected to the negative supply terminal (1)

    as for reading resistor colour codes
    my crash course in reading resistor colour codes was buying 10 of each resistor value from 1ohm to 10 meg ohms
    they arrived all jumbled together in one bag ! (850 resistors I think it was )

    first lesson , don't try it under Fluorescent lighting !

    variation in paint colours used by the resistor manufactures and errors in the colour balance of the camera and your monitor
    makes reading the values from photos more difficult !


    MAG45

    your first picture in post 37 makes it a lot easier to follow the printed circuit
    and see all the track to the D-type pin 10 has disappeared !

    does the limit switch or what ever connect +5V to the BOB's input terminal ?



    John

  4. #44
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    No, the limit switches are just microswiches from the bob, through the switch and back to the bob. The only power to the bob is from a red wire on the atx pws as far as i can tell.


    Just to add, this setup was running for about a year and a half before I started having consistent problems. Just had random false e-stop errors at first, then my Z axis stopped repeating while running a program, but would repeat if i jogged it with an indicator on it.

  5. #45
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi MAG45

    just trying to work out how the track was damaged

    while most micro switches only ground the BOB's input when the contacts close as shown in the PMinMO manual

    on odd occasions I've come across switches switching between ground and a current limited positive supply

    John


    PS
    is the 25 way D-type connector connected to a PC printer port or some other controller ?

  6. #46
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    It did fall free in that case, and with that wire mess who knows what it ran into ! lol

  7. #47
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    Is there anything I need to do a this point ? Or just waiting for things to be figured out ? No answer from Gecko as of yet.

  8. #48
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi MAG45

    did you have a batch number or serial numbers for Gecko Drive to identify your drives and find out if they are a special version ?

    I assume the boards LS1-1 switch input fell onto a positive motor supply connection
    that would explain the damage to the PCB track and the resistor

    the problem is the damage done to the motion controller or PC printer port connected to the breakout boards 25 way D-type connector

    on the Gecko web site there is the circuit of a step / direction tester you can use to test the gecko drive
    I'm not sure of any ready made version for sale any where
    I'll have to do a quick web search and see what's available

    John

  9. #49
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    If any of the Geckos are shot, I have one new 'bigger' one that was going to go on my Z axis at one point.

    I found this too
    Click image for larger version. 

Name:	IMG_20150203_152907322.jpg 
Views:	0 
Size:	65.4 KB 
ID:	267358

  10. #50
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    Other Gecko

    Click image for larger version. 

Name:	IMG_20150203_172608106_HDR.jpg 
Views:	0 
Size:	80.6 KB 
ID:	267372

  11. #51
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    Hey John, Did the last Gecko info I posted explain the resistor for you?

    I found a resistor in my dads old electronics bin and replaced it on the BOB. Is there any harm in putting it back in and seeing if it works?

  12. #52
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi Mag45

    I've had a few distractions but , Yes I've had a look at both the picture of your spare driver and page from the manual you posted

    should be OK as a spare drive


    I have found 3 ready made pulse generators here :-


    Servo/Stepper Testing : Get Hubbed, The Art of CNC

    the lack of information makes it difficult to decide which one I'd use instead of building the Geckodrive version


    John

  13. #53
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    Do I need a pulse generator? If so this project will be put on hold for a while.

  14. #54
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi MAG45

    if you can't get your control system to work after replacing or repairing the damaged BOB

    a pulse generator is just a handy tool to prove the stepperdrives are OK

    John

  15. #55
    Join Date
    Jan 2015
    Posts
    84
    Quote Originally Posted by john-100 View Post
    Hi MAG45

    if you can't get your control system to work after replacing or repairing the damaged BOB

    a pulse generator is just a handy tool to prove the stepperdrives are OK

    John
    Oh, okay...do you think there is any problem with trying my BOB with the replaced resistor?

  16. #56
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi MAG45


    I expect you will need to change 1K resistor R5 and the red light emitting diode LED 5

    - note the position of the flat in the red resin case

    Attachment 267592

    the cathode (k) is connected to the terminal block and your wire link that replaces the burnt out track

    John

  17. #57
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    Okay, thanks, will check to see if I have LED's

  18. #58
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    No LED's that size, just some bigger ones. Will it run without the LED or is that part of the connection ?

  19. #59
    Join Date
    Mar 2007
    Posts
    2083

    Re: Help me find a BOB !

    Hi MAG45

    yes , once the burnt 1K resistor has been replaced

    you can apply the 5V supply and test the board on your workbench


    using a 25 pin plug will make it easier to test the continuity between the limit switches and the boards 25 way D type socket


    if you short the limit switch input LS1-1 to ground terminal LS3-2

    LED 5 will light if its working - its possible its open circuit or no longer emits light


    if the LED is open circuit just short it out so R5 acts as a pull up resistor for LS3-2 and the D-type pin 10


    with no connection between LS1-1 and ground

    you should have around +3.5V to + 5V between the D-type pin 10 and ground ( pins 18 to 25)
    the voltage measured depends on the meter you use

    repeat the test for the other four limit switch inputs LS1-2 to LS3-1


    John

  20. #60
    Join Date
    Jan 2015
    Posts
    84

    Re: Help me find a BOB !

    Okay, put the BOB back in wired as it used to be (still a mess) but didnt want to change anything yet. With linux CNC i had to "override limits" to allow it to make the control live. I was then able to to jog all 3 axis. But at the end of the jog the software/controller would darken and give me a limit error at port 0, 1, or 2. I could revive the controller and jog back, as soon as i stop, error again.

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