No axis movement.

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This topic contains 9 replies, has 2 voices, and was last updated by  Scott McGraw 3 days, 18 hours ago.

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  • #3026

    Scott McGraw
    Participant

    I know for sure I burnt the driver chip on my Y axis, and in troubleshooting that have lost movement in all axis. I still have 5v reference and 36V to all motor drive pins, other than the one that is obviously fried. Would it be safe to assume I can replace the three chips and get back up and running?

    #3027

    BrianV
    Keymaster

    Well, I’m curious what you did to fry the chip.

    It is highly likely that replacing the blown chips will restore operation.

    Not sure what board you have (no record of you in the HobbyCNC customer database).

    The 7404 chips might be whacked too, depending on how creative you were in the demolition of the driver chips.

    BrianV

    #3028

    Scott McGraw
    Participant

    Sorry, I have a 4 axis pro board that I was able to find assembled on ebay about a year ago. I have not directly purchased anything from your site. I am not sure what I did to burn the first chip, but in troubleshooting I crossed two wires and that’s when the other axis stopped working. Is there anyway to test the 7404 chips?

    #3351

    Scott McGraw
    Participant

    Not sure why, but it appears my post disappeared as well. I purchased a 3 axis pro board, and after completing the initial assembly, I had 4.93v at the test point. I completed the rest of the assembly, set the current on all three axis to .42v, and installed the board. Initially, I had very slow movement on the y axis, and none on the other ones. After a few minutes, the motor shut down as if it were going into protect mode. If I turn the board off for a few minutes and turn it back on, it goes for about 5 secs, then shuts down power to the motors again. I removed the board, verified I still had 5v, and checked the current on the axis again. I had .42 to x and y, but now have no voltage at all on the z pad. I am using a 12v pwr supply for testing and have 11.79v on the U6 resistor, and 4.93 on U5 and U7. I also have continuity on all three posts of the z axis pot. I have also verified everything is oriented correctly, and all solder joints appear solid with no bridges. Thanks for any help, Scott.

    #3352

    Scott McGraw
    Participant

    I did notice as well, U6 resistor appeared to get very hot when I had the board hooked to my 36v pwr supply. I could only hold my finger on it for about 1 sec.

    #3359

    BrianV
    Keymaster

    Not sure why, but it appears my post disappeared as well. Some content was lost during the site upgrade – changes between when I made the copy and when I uploaded the new site. My apologies.

    Product: 3 axis pro board,
    4.93v at the test point Good!.
    The current on all three axis to .42v This will set motor current to 3 Amps..

    Initially, I had very slow movement on the y axis, and none on the other ones. After a few minutes, the motor shut down as if it were going into protect mode.

    If I turn the board off for a few minutes and turn it back on, it goes for about 5 secs, then shuts down power to the motors again.

    I removed the board, verified I still had 5v, and checked the current on the axis again. I had .42 to x and y, but now have no voltage at all on the z pad. Something is amiss in that circuit – see below.

    I am using a 12v pwr supply for testing and have 11.79v on the U6 resistor, and 4.93 on U5 and U7. This is smart to use a low-voltage low current for initial test – but 12V is probably not sufficient to make these motors move, or at least move well/quickly.

    I also have continuity on all three posts of the z axis pot. I have also verified everything is oriented correctly, and all solder joints appear solid with no bridges.

    U6 (R6?) resistor appeared to get very hot when I had the board hooked to my 36v pwr supply. I could only hold my finger on it for about 1 sec. R6 is part of the Z axis idle current reduction circuit. It is part of a simple voltage divider and under no circumstances would it even get slightly warm. I might suspect R5 or R6 is the wrong value (both should be 10k Ohms), U9 could be backwards. Look again closely in the geography or R5-R6-Q6-U9 for a small bridge.

    #3360

    Scott McGraw
    Participant

    I was referring to the U6 location on the board. The 7824 chip. It gets very hot. I checked all the resistors before installing them and they were 10kohms. When I apply pwr, I have 4.93v on one side of R1 and R3 resistors, and .42 on the other side. On the R5 resistor I have 4.93v and O.00v. on R2-R6 I have 4.93v on both sides. U9 is oriented correctly, and I see no bridged joints. I may be over thinking this, but I do have 4.93v on all three posts of Q6, but see no bridges.

    #3361

    BrianV
    Keymaster

    U6 (7824) should not run hot. It only connects to two things: the 5V regulator and the fan connector.
    Are you running a fan? are you pulling anything else off the fan connector? What voltage is on both sides of R15? One side should be 0V (ground) the other around 31.5V (when connected to the 36v supply. U7 takes some of the load off of U6 for higher power supply voltages.

    #3362

    Scott McGraw
    Participant

    With the 12v supply hooked up I have 9.83v on one side and O.00v on the other side of R15. I am running a fan and nothing else off the fan connector. I have 0.00v on both sides of the C17 capacitor.

    #3370

    Scott McGraw
    Participant

    I still have not been able to figure this out. Not sure were to go from here. Is there a process that shows the power flow of the board so I can track down the x axis?

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