[Aaronsg]

Hi Everyone.

I have the same issue with 3 axis TB6560 board missing steps and low speed
what ever i try on mach3 to eliminate the problem wont work.
the best working almost no missing steps is reduce the current to 25% and micro-steps to half but then the speed is not there, Increasing the speed result to stall the steppers.
If i preform the buffer will it increase the speed too

specs are Nema 34 890oz-in with 24 volt power supply on mach3. settings are 15000 per steps, 20 velocity /mm, acceleration 1 mm/sec, step puls 4, dir puls 4.

Regards,
Aaron

[lasik2025]

Hi Everyone.

I have the same issue with 3 axis TB6560 board missing steps and low speed
what ever i try on mach3 to eliminate the problem wont work.
the best working almost no missing steps is reduce the current to 25% and micro-steps to half but then the speed is not there, Increasing the speed result to stall the steppers.
If i preform the buffer will it increase the speed too

specs are Nema 34 890oz-in with 24 volt power supply on mach3. settings are 15000 per steps, 20 velocity /mm, acceleration 1 mm/sec, step puls 4, dir puls 4.

Regards,
Aaron

Aaron,

For me, buffering the CLOCK (eg STEP) line for each driver IC fixed the missing step issues. But before I committed to change the entire board, I did try out the buffer fix on a single driver. For a second trial, I added connections to a 2nd driver. See attached picture (the picture shows the buffer temporarily wired to 2 drivers). I just used breadboard of buffer circuit, then connected wires to +5v, gnd, TB6560 pin 3 CLOCK input, the corresponding optocoupler output for CLOCK (by following the printed circuit board trace from pin3 backward), then finally cut the trace with small knife. I figured that if the buffer did not work, I could just repair the cut trace with a small wire to return the board to its initial state.

Lasik2025

[circuitz]

Good call, forgot about the cable loading and so re-measured.

I used an oscilloscope probe. On 24VDC, the x1 setting on the probe showed 45.62kHz, the x10 setting showed 40.38kHz. Of particular note the readings varied by several hundred hertz from second to second despite being careful with the probe grounding. There was no motors attached. The cap silk screen is marked 102 aka 1nF.

The heatsink reference occurs on page 28 or page 26 depending of the date of issue of the datasheet.

"Treatment of Heat-Radiating Fin
The heat-radiating fin pins of the TB6560AHQ/AFG (backside) are electrically connected to the backside of
the die. Thus, if a current flows to the fin, the IC may malfunction. If there is any possibility of a voltage
being generated between grounds and the fin, the fin pins should either be connected to ground or
insulated."

Also attached is an image of the pin 23 to pin 25 overlap on the 3-axis driver before trimming back with side cutters.