[Linksauce]

As much as I dislike having to ask for help, I'm at a loss for this one.

I first added the 74HC14 and removed the current reduction circuit on the Y axis driver. This actually made it perform worse. The motor would turn, but much slower than it should have been and along with the sound of it missing the majority of its steps. I then removed the optocoupler, which provided the fix I was after; the axis moved smoothly and, as well as my short testing could show, took care of the loss of steps. I then tried replacing the 1000pF cap with a 151pF (I didn't have any 100pF caps readily available). No noticeable results over the removal of the opto, but it didn't make anything worse.

I then applied these changes to the other two axes, with the only difference being that I desoldered the transistor and capacitor that made up the current reducer circuit completely. The Z appeared to work fine, however the X would stall if it got anywhere near the speed it should have been going (90IPM), and would still audibly miss steps even at under a third of that speed. Stranger still, after further pondering and testing, I discovered that, should I attempt to move the Y and the Z at the same time, the X would try to move, too. All it would manage is a grinding noise and slight turning in whichever direction it was last moved, but it was a consistent and repeatable effect.

I've checked every connection and solder joint a dozen times by now and I'm certain I didn't screw anything up as far as that goes. The only thing I haven't tried that I think might be applicable is grounding the heatsink, but I was under the impression that that was mostly a safeguard against a cascade failure between chips...

Any help? At this rate, I'm ready to grab a couple new TA8435H chips to replace what I burnt on my first controller.

EDIT: Well, damn, looks like the problem was one of the wires sitting funny in my breadboard. Fiddling with it fixed things.

As a side note, thanks much to the OP. I'd have been very sad had I not been able to fix this thing. As it stands, this thing now goes FAR faster (up to double the original 90IPM I was getting if I use whole stepping) than it used to on the old controller. Good times.

[Linksauce]

I take it back. It wasn't a loose connection.

It was me holding the wire that fixed it. For whatever reason, the extra capacitance I provided (I didn't even need to be touching the bare ends of the wire, just holding the insulation) fixed the signal. I played with it some more and tried sticking a 10pF cap between the signal and ground, which I guess cleaned the signal up and it doesn't skip anymore.

I have no idea why this worked, and, moreover, why only this one axis had this problem. If anyone wants to speculate though, I'd be interested in hearing it. Note that I don't have an oscilloscope because poor.

[H500]

A 10k resistor to ground would also reduce the noise pickup from the wires.

[cnchobbyman]

My 3040 also develped x-axis missing steps problem. But it only missed steps in one direction. My setup is on LinuxCNC. Tried to slow down the pulse rates but not helping at all. Every single test pin-pointed problem back to the X-Axis driver. The problem seemed getting better when I probed (scope) the TBA6560 pins. So I ordered a replacement TBA6560 but not helpful either. But I am glad that the new chip is genuine.

The next step was to trace the circuit. My controller is a simple one that comes with the CNC. It has all three axis on one board. I have the picture but don't know how to post it..:-(

To make the long story short, I did two things that have fixed the problem so far:

1. Soldered thick wires on board between the X axis driver circuit and both 24V and ground input. There's quite a bit a voltage spikes observed on the TBA6560 driver chip that could increase signal noise and has the potential of damaging the driver.

2. Replaced the "motor current swicthing (between running and idling)" circuit with one I put together using 555 timers as retriggerable one-shot. The original circuit design has two problems I could see. 1) It's sensitive to step pulse width; 2) The control polarity is wrong.

After the changes, my CNC machine can now run a 6 hours job without observable missing step problem. Before that, I could see it would drift to the right for about 1/8 inch on x axis in about 15 minutes. And I could hear the stepper motor "jumping" noise.

Hope this helps.

[landau]

Hello everyone,

i did the 74HC14 mod, but with poor results! Steppers go very slow and lost some steps! Do you know why?

Thanks

[LanceJ]

Hey guys,

I have the 3 axis TB6560 board. Does anyone have a picture of the mod they did showing the traces that needed to be cut?
I've seen the 4 axis pictures but the traces look slightly different from the 3 axis and i don't wanna cut the wrong ones. Thanks

Here is a picture of the board i have and the buffer i made.
Attachment 216986Attachment 216988

[rudolf.pajtina]

hi,
I have probably the same type of the board and I was solving exactly same problem couple ofdays ago.
One of the connector designation is NXG-05, it is not so easy to find it on the market in quantity of 1-2 pcs.
But good matter is that the same connector is inside classic PS2 or USB mouse. Other end of compurer connector.
I opened mouse and pull-out the cable and use a cable with crimped connector.
This is the most easier way.

[nar]

Here's a good one for you troubleshooters. In the process of bringing up a new TB6560 4-axis board with Mach 3 I observed that the Y-axis direction was always CCW. Out comes the o'scope: the signal is good from the DB25, it's good on the Schmidt trigger (pins 1 and 2), but that's where the good news stopped. There was a paltry signal present at the input of the applicable optoisolator, not enough to trigger it.

Careful examination of the underside of the board revealed a solder blob (factory installed) shorting out one of the surface mount resistors in that chain to its neighbor. One small flick with a soldering iron, problem solved.

Please see attached photo. Pretty shoddy testing!

Attachment 218808

Neil

[DavieMachine]

I have TB6560 blue board 3 axis.. I want to know how to hook up a spindle on/off control using the relay on the board to turn on a larger 24v relay. but can't find any info on the relay and the pins that control the relay on DP-25 connector. Im converting my bad Emco F1, while using my good F1 for work... Love the cat-30 quick change tool holders.

[jmp2014]

Newbe here and a another victim of the cheap Chinese TB6560 driver board. Would like to perform the updates listed, but!! My board doesn't match the others pictured. Mine is blue in color but my capacitors are on the other side of heat sink (next to motor connectors) . The traces on the board don't match with ones pictured. The only numbers on board 30695S. Mine was bought off ebay from long-motors. I will try to get a picture of it tonight. Anyone have any thoughts.
Thanks

[jmp2014]

Attachment 232920Attachment 232922
These are the pic of my chinese 3 axis driver. Looks different than the ones listed on here for mods. Can anyone explain mods for this style? Any help would be great.

[Jamb00]

Same board here jmp2014 i can see it have 2 74HC14 this is good but the Optocuplers are slow EL817 needs more investigation.....

[Joh-nny]

I got myself the "newest" edition of this board (chinese blue tb6560 3 Axis). The same one Jamb00 and jmp2014 got.

Attachment 245532
Attachment 245534
Attachment 245536

There are now no smd or other components mounted on the underside. Pin 25 still needs shortening

Modifications I made(so far):

1) L7812CV to power the fan (12V regulator still got seriously warm)

2) Grounded the heatsink

I think merely the Layout was changed (Please do tell me if there are some other changes), so I will be doing the other mod's from earlier in this thread.

I'd appreciate it a lot if anyone who has made any of those modifications would post something usefull. I will also contiue posting updates.

[Gall]

Still no real optical isolation. Common ground. Dangerous.

[Joh-nny]

I'm taking care of that with a selfmade opticaly isolated arduino shield (I'm using arduino and grbl)

C25, C26, C27 (Below the heatsink connected to pin 7 - OSC and Ground) should be the caps that regulate the internal frequency -> replace by 330pF to 100pF (previously successfully used values). I do not know what the current capacity is, as I don't have the tools to measure that. Would be nice if someone could do that.

[Joh-nny]

Replacing C25, C26, C27 [marked in orange] (Below the heatsink connected to pin 7 - OSC and Ground) and desoldering "the current saving feature" R55, R60, R61 [marked in red] (between heatsink and 10uF elektrolytic capacitor), definitely reduce noise a lot and increase precision.

Attachment 246264

Jumpering the useless Optocouplers didn't seem to work with my board, steppers got really loud and didn't move at all.

Do you need to invert the step and direction signals of the jumpered optocouplers (which I have not tested)?

Which step pulse duration are you using with which size of Osc-Capacitor?

So far the best setting I have found is 15us with a 100pF Capacitor. With every setting but full step mode ( 1 ) it's working nicely, in full step mode movement is occasionaly a bit jerky.

[Jer7440]

My 12 yr old saved his money and bought a kit, off ebay, that included this latest tb6560 3 axis board (the one Joh-nny is working with), a 24v power supply, and 3 nema 23 6 wire motors. He's building a small cnc dremel/router. Nothing real complicated...2x4 frame, ball bearing drawer slides for guides, threaded rod for screws. We're trying to hook up one motor, to test out the system. We haven't even been able to get one axis to spin. I've read several things about the ports and pins in the instructions being wrong. We've tried several different settings and still nothing. When we hook up to the x axis, the motor locks up but will not turn when we jog in mach3. Now I'm reading about all of these mods to make the board work...I'm starting to think we are in way over our heads

Can anyone verify working port/pin settings for this board? Can anyone give us some basic ideas to at least get this thing to spin? I have a very disappointed 12 yr old, right now!

[rajshinai]

Hi Jer,

I have the latest one too. These boards always work, the error is mostly with the software settings and later with steps sometimes. If the motor locks that means u r doing it right. Play around in Mach 3 and check some videos on youtube. I had a similar experience initially, bt managed to run after a lot of trial n error.

[Joh-nny]

Did you invert the enable Signal? It needs to be set as low to disable steppers, high to enable them. I didn't do that the first time i tried my board and had the same problem.

Also the mod's really aren't that difficult to do. You might even find that the board is usable as it is, especially if it's only for a small machine. Play around with the settings switch to halfstep mode. I'm sorry that I can't give you detailed instructions on how to set up mach3, as I'm using an Arduino to stream the G-Code via a usb-connection.

[Jer7440]

Joh-nny, this is the first I have heard of inverting the enable signal. Is this a setting in Mach3? Which page? Thanks for the help!