Driver chip burnout!

[Merv]

Hi. Can anyone help me with a problem?
I have bought a cnc wood router that i am told uses nema 23 motors and it is fitted with a four axis control board using Tb6560 driver chips. The problem is that the chips are blowing on a regular basis (small hole and lots of smoke).The motors have no labels and 8 wires.They look big to me and I wander if they may be drawing to much current and causing the problem?? I bought a new power supply with the last board and things have been fine for a few cuttings but this morning when I started to move it went again. I am getting fed up with soldering new chips and am desperate to make my machine reliable. I have ideas and projects comming out of my ears and it is so frustrating to be stuck like this.
I have the higher amp board.
Should I use a different driver and if so what?
Any help would be realy appriciated
Merv

[Tweakie.CNC]

Merv,

Your driver board sets the current that is applied to the steppers and  it sounds like it is set too high. Do the motors get hot to the touch during operation ?

Tweakie.

[Merv]

Thanks for your answer.
Depends what you call hot.I would say on the warm side but you could not hold them in your hand for very long.
I have had three different boards and same problem.
That said, how can I change the current that my board supplies?
Could I add resistors?
What would happen if I got higher amp drivers?
Thanks
Merv

[Mishawaka]

What the number on the driver chips? You might be able to cross them over to a better chip. Not sure that would be wise but may be worth a shot.

[ostie01]

You would need very big resistors.

Do you have pictures of the board.

The first thing I would do is add much bigger heat sink

Second, add a fan to blow cool air at the heat sink.

Maybe find which resistor on the board is limiting current to the motor and calculate a value for less current.

Jeff

[Tweakie.CNC]

If your motors are not getting hot then I would look for an intermittent or poor connection between the board and motors (a sudden open circuit here can destroy the driver chip) connectors, soldered joints etc.

Tweakie.

[RICH]

Merv,
Please post the documentation for the board you are using.
Make sure it is correct one for the driver board you are using as there seems to be conflicting info on them from a quick check I did.
What is the power supply voltage?
Can you post info on the motors?
How do you have the motors wired? Amp draw is different depending on wiring configuration.
Is there a current setting dip switch on the board?

RICH

[Merv]

Thanks for everybody's help.
I have had a good look at the wiring and a couple of the soldered joints are very sloppy, also the wires are in metal tubes (a bit like a shower hose) and the connections at the ends are a little loose. I wonder if the bare connectors inside are making contact with the tube when the machine is moving? Anyway I have ordered a new control board and while I wait will replace all the wiring between the steppers and the board. If this solves the problem I will let you know and it may help someone else. If not I will give as much info about the system as I can and hope you guys can help.
Merv