[circuitz]

Hi lasik2025,

I was busily reversing engineering a 3-axis controller when another user 'doorknob' pointed out your existence over on this forum page.

Here's some more flaws for the list.

- There is a FR301 diode in the motor voltage supply to each TB6560. When back EMF hits, that current can only dump into the 3300uF decoupling cap. The volts increase and folks on this forum start practicing their French. >> replace the 3 culprit diodes with fuses.

- No back EMF diode on the coil of the relay >> add diode

- Pins 25 of the TB6560 extends over the trace from pin 23 >> trim back

- Heatsink not grounded. The resistance from heatsink to ground is small but non-zero. When failure occurs substrate currents will help the remaining TB6560s to join the party >> according to the datasheet isolate each device from the heatsink or simply ground the heatsink

On the OSC pin issue, I observed a nice sawtooth waveform, ranging from 0.5V to 2.5V, with a frequency spread from 38kHz to just slightly over 40kHz.
The max step rate for the TB6560 is 1/4 of this.

[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.

[lasik2025]

Hi lasik2025,

I was busily reversing engineering the exact same 3-axis controller when another user 'doorknob' pointed out your existence over on this forum page.

Here's some more flaws for the list.

- There is a FR301 diode in the motor voltage supply to each TB6560. When back EMF hits, that current can only dump into the 3300uF caps. The volts increase and folks on this forum start practicing their French. >> replace the 3 culprit diodes with fuses.

- No back EMF diode on the coil of the relay >> add diode

- Pins 25 of the TB6560 extends over the trace from pin 23 >> trim back

- Heatsink not grounded. The resistance from heatsink to ground is small but non-zero. When failure occurs substrate currents will help the other 2 TB6560s to join the party >> according to the datasheet isolate each device from the heatsink or simply ground the heatsink

On the OSC pin issue, I observed a nice sawtooth waveform from ranging 0.5V to 2.5V with a frequency spread from 38kHz to just slightly over 40kHz.
The max step rate for the TB6560 is 1/4 of this.

circuitz,

Thanks for the additional information & investigation.

I mistakenly assumed the SOT23 device on the backside behind the relay was a relay coil back emf protection diode; but it is instead an PNP transistor driver. I have updated the slides (atttached to this post).

On MY TB6560 board (4 axis version), the pin23 to pin25 short does not exist. Everyone should check THIER boards for this issue however.

I did not see the datasheet reference to grounding the heatsink. The pdf I found on the web somewhere has header "TOSHIBA TB6560AHQ/AFG" and footer "2009-07-10".

Thanks for the OSC pin info on observed frequency. May I ask what the capacitance of the probe you used to measure it ?

Lasik2025

[brutusgraphics]

Hi all,

Ok I finally figured out how to solve my problem.. After all this time , I could not get this turd ball to run so I ordered a Gecko drive 540 or whatever you call it.
It's on the way. Wished like hell I would of shelled out the extra bucks for it in the first place. I bought mine for $239 from Automation Technology Inc. | Stepper Motors, Servo Motors, CNC Stepper Motors, Stepper Drivers, CNC Kits, Stepper Kits Automation Technology Inc and with shipping and tax it came up to $270 - ish. I'm not associated with Gecko or Kelling Just a guy who wants things to work when I pay for them. From the reviews I've read about the drive, I have no doubt it will be a real jewel.