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IndustryArena Forum > CNC Electronics > CNC Machine Related Electronics > How I fixed my Chinese TB6560 controller (updated)
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  1. #521
    Join Date
    Jan 2005
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    1695
    Here's how I would do it, after looking at the specs more carefully.

    R upper fet = .4 ohm
    R lower fet = .4 ohm
    R total = .8
    I = 3
    P = 3^2 * .8 = 7.2 watt per coil driver

    P = 7.2W *2 = 14.4 watt per chip

  2. #522
    Join Date
    Jan 2005
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    1943
    I got my single axis TB6560 board today and noticed somthing and had some questions.

    I noticed that the optocouplers are different than the ones on the multiaxis boards. I'm hoping that means these optocouplers work right out of the box and don't have the speed and wiring issues of the multiaxis boards. From my research it looks like the multiaxis boards use the PC817 optocouplers where this board uses three different optocouplers for different things. The enable circuit uses a P521GB optocoupler, the direction circuit uses a 4n35 optocoupler, and the step circuit uses a 6n137 optocoupler. I looked briefly at the 6n137 datasheet and it looks like it is a high speed optocoupler that would do better than the ones in the multiaxis boards. Provided that everything is wired right that is.

    The questions I have relate to switch settings. This unit has 4 different things that can be configured, motor current, microstepping, stop current, and decay setting. No probelm on the current and microstepping, but can someone explain what stop current and cecay setting refer to? The options are 20% and 50% for the stop current, and 0%, 25%, 50%, 75% and 100% on the decay setting.

    I also noticied when looking more at the TB6560 datasheet that page 28 contains the following formula for calculatind power dissipation of the chip.

    P = VDD × IDD + IOUT × Ron × 2 drivers

    Where Vdd=logic voltage, Idd=logic currrent, IOUT= motor current, Ron=Output on resistance (upper an lower combined)=0.6 ohms (page 1 of datasheet)

    So, lets say the Vdd and Idd is provided by a wall wart PS with 5V DC, 500mA rating

    P=5*0.5+3*0.6*2 = 6.1 watts power dissipation. The graph on page 27 shows that the chip with a heat sink (not an infinite one) can dissipate 25 watts up to an ambient temp of 25 deg C (77deg F). Even if the temp in the enclosre gets to 75 C (167 F), the chip can dissipate 15 watts. Well above the 6.1 watts calculated.

    edit: Well I noticed something else. There is no separate input for the logic power. There is a 5V 500mA regulator on the board, so that is where they are getting logic power. So, there is no way to do the power on cycle separately. We'll have to see how that goes. The dissipation calculations don't change though. If I wind up blowing the chip due to the power on cycle, I may modify one of these boards to eliminate the regulator and provide the 5V logic power using a 5VDC wall wart like I had planned. I'll try it the way it is though first.

  3. #523
    Join Date
    Feb 2007
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    962
    Quote Originally Posted by 109jb View Post
    I also noticied when looking more at the TB6560 datasheet that page 28 contains the following formula for calculatind power dissipation of the chip.

    P = VDD × IDD + IOUT × Ron × 2 drivers

    Where Vdd=logic voltage, Idd=logic currrent, IOUT= motor current, Ron=Output on resistance (upper an lower combined)=0.6 ohms (page 1 of datasheet)

    So, lets say the Vdd and Idd is provided by a wall wart PS with 5V DC, 500mA rating
    Watts = I^2 x R , It should be (IOUT^2)

    P=(5*0.5) + ((3*3)*0.6*2) = 13.1 watts power dissipation.
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

  4. #524
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    Jan 2005
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    1943
    Quote Originally Posted by Larken View Post
    Watts = I^2 x R , It should be (IOUT^2)

    P=(5*0.5) + ((3*3)*0.6*2) = 13.1 watts power dissipation.
    I caught that too but it is in Toshiba's data sheet without the squared term. maybe a mistake but I was just reporting what the data sheet says. in either case it isn't enough to worry about if the chip has a heat sink.

    So can anyone explain "stop current" and "decay setting". I have a hunch what they are but would like to hear from some of you guys that have been there before.

  5. #525
    Join Date
    Jul 2011
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    Stop current is the current used to hold the motor shaft at a stopped position.

    Decay is the decay current in the motor coil after the voltage is changed. This setting determines how the IC manages that current.

  6. #526
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    Jan 2005
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    Quote Originally Posted by drmacro View Post
    Stop current is the current used to hold the motor shaft at a stopped position.

    Decay is the decay current in the motor coil after the voltage is changed. This setting determines how the IC manages that current.
    Well the stop current I had correct in my mind. So that is basically to reduce current to the motor when it is stopped and thereby reduce unnecessary heating of the motor. So this you would set as low as possible to hold position. Correct?

    On the decay, then 0% would be a slow decay which I would assume would be a smother transition from step to step as one coil increases in current and the other decreases. 100% would be the fastest decay which I would think means that one coil de-energizes quickly and the other gains current so the motor will move quickly to the next step and then slow down when in position and then it starts all over again. So it would seem that slow decay would be quieter and smoother, fast decay would result in noisy operation. Do I have this right? If so, What is the drawback to slow decay then? Can too slow cause the motor to lose steps?

    In a nutshell. What is the best way to go about setting these parameters?

  7. #527
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    Jan 2005
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    1943
    I have decided to modify my single axis TB6560 board so that the power on sequence can be accomplished correctly. It really isn't that hard to do. On the board is a 5VDC voltage regulator. It supplies all of the 5V needs for the TB6560 IC and anything else on the board that needs 5V. I simply plan to leave the VR on the board, but take the VR out of the system and tie in a wire to feed the 5V from a 5V wall wart. It will reguire cutting 2 small lugs and soldering on one wire. The photo shows what will be done. The negative side of the 5V power supply will just connect to where the 24V motor supply negative feed connects as it is electrically common with the common lug of the VR.
    Attached Thumbnails Attached Thumbnails IMG_1359-1.JPG  

  8. #528
    Join Date
    Apr 2012
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    EMC2 / LinuxCNC

    I have a 3-axis version of this board and have noticed that it occasionally missed a few steps. I have read this thread start to finish and decided that the most likely changes to fix this would be to bypass the opto isolators, remove the 10k resistor for the power reduction circuitry, and replace the clock capacitor with a 100pF one. The first change (optos) made no noticable difference, at least on its own. The second did allow me to increase the speed by about 10% and subjectively everything seemed quieter and smoother. The final change, the clock capacitor, made a significant difference - it quietened everything down and allowed me to double the speed of everything. The issue is that after that last change when I push the jog buttons in LinuxCNC the machine continues to move for about 3 seconds after I release them.This is quite unacceptable and is potentially disastrous. I have tried all sorts of timings and within the range in which the machine functions it makes no difference. It happens on all axes.

    Has anyone else had any similar issues?

  9. #529
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    Does it happen at low speeds? (ie: 5 IPM)

  10. #530
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    Apr 2012
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    Yes, it is independent of speed.

  11. #531
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    Quote Originally Posted by MalcolmF View Post
    Yes, it is independent of speed.
    Do you have access to an oscilloscope?

    The next thing that I would check is to see if the PC is actually sending step pulses to the board during the time when you are not jogging it, or to see whether you can detect noise or some other signal going to the step input of the TB6560 (that may not be coming from the PC).

  12. #532
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    Unfortunately no, I don't have an oscilloscope. Open to suggestions on other ways to detect this - obviously just sound doesn't work as the motors are spinning when this is happening. I might be able to rig an LED across the relevant input...

  13. #533
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    Jan 2010
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    Unfortunately an LED alone is not likely to give you any useful information.

    The step pulses (or noise) would be extremely short in duration, on the order of at most a few microseconds, so you would not see that on an LED.

    An oscilloscope is really the right tool for performing this test. Do you have a friend who is an electronics enthusiast who might be able to bring over a portable oscilloscope to do the test?

    As an alternative (not as useful, but might work) maybe you could find someone nearby who has a logic probe that you could use...

    If you are handy at soldering and have a nearby electronics parts shop, I suppose that you could buy parts or a kit to put together your own logic probe (or find such a thing on eBay).

  14. #534
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    In my experience, although you can't see individual pulses, an LED across a parallel port will glow if the pin is active - I'm not sure whether it will work with the tb6560 board attached though. In fact, now that I think about it the board does have some LEDs on it - I need to go back and look at the circuit digram because what I've suggested might already be there...

  15. #535
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    Quote Originally Posted by MalcolmF View Post
    In my experience, although you can't see individual pulses, an LED across a parallel port will glow if the pin is active - I'm not sure whether it will work with the tb6560 board attached though. In fact, now that I think about it the board does have some LEDs on it - I need to go back and look at the circuit digram because what I've suggested might already be there...
    It's a useful suggestion, however my goal at this point would be "problem source isolation", that is, determining whether the LPT port is actually putting out pulses or whether noise or pulses from some other source may be getting into the TB6560 chip, or whether something entirely different and unexpected is going on. Once such a determination has been made, you can then focus your attention on getting to the root of the problem and addressing it.

    That task will require some probing around at various parts of the circuit, cable, and connectors, with and without the board hooked up.

    So, while the onboard LED(s) might conceivably provide some diagnostic information, using a movable probe would be more flexible and likely to give a more complete picture of what is going on.

    With a plain LED as a test probe (possibly with a series resistor), you would also run the risk of loading the circuit which could affect and confuse your test results.

  16. #536
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    Mar 2007
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    2083
    Hi Malcolm ,

    you could use a logic probe like this one from maplin -

    Logic Probe : Basic Test Equipment : Maplin Electronics

    to test the printer port pins used as step signal outputs
    then see if the computer continues to send step pulses after you release
    the jog button


    you will need an adaptor cable to ,either to take power from a usb port
    or ps2 keyboard/ mouse connector for example

    if the board is the one I'm thinking of
    the step and direction signals will be available at the 15 pin D-type connector
    normaly used to connect the blue manual control thats available for the
    tb6560 stepper boards
    if you need to test the board
    a 5V supply is available at the 15pin Dtype connector - be carefull not to shortcircuit it! or you will destroy the TA6560 ic's


    John

  17. #537
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    Jan 2005
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    It sounds like your parallel port might not be compatible. Use a voltmeter to measure the high and low voltage levels with the drive connected. The lows should be <.8v. The highs should be >2v.

    Are you able to try another computer?

  18. #538
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    Mar 2012
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    Which of the marvelous TB6560 based boards is this by the way. Many sour flavors of this chip/board.

    The mouvement AFTER the application JOG button is released could be just about anything and may not be related to the changes done to the board at all or simply coincidence.. could be keyboard button bounce, could be buffer overrun, could be timming was thrown off with the modifications to the board and the added speed you gained.

    You have another computer/software you can test with ?

    MP*10

  19. #539
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    Thanks for all the help - looks like I'll run up to Maplins and get a logic probe.

    I get the impression that no-one else has had this issue when they put in the 100pf caps then. My problem is trying to understand how this could affect the apparent behavior of the software, and I'm hampered by not really understanding the relationship between the TB6560 clock and the timings in LinuxCNC and the parallel port pulses. Is anyone able to provide a good explanation of this relationship?

  20. #540
    Join Date
    Dec 2007
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    2134
    Aside from the numerous issues with these controllers, it's not uncommon for some modern motherboards to put out varying logic levels via the parallel port, that sometimes requires a logic shifter or buffer to clean up before being fed to the input stage of the controller. This may possibly be an issue with yours, have you also verified the BIOS has the appropriate parallel port type set for the controller? Enhanced, ECP, etc?

    cheers,
    Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

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