# Retrofitting The "famous" Tb6560 Cnc Board



## petcnc

*DECLARATION*

I’m in no way an electronics expert and all modifications I have made to the board (and the rest of my machines) are based on research, common sense and experimentation.
I upload my modifications here for educational purposes only.
It is neither the best nor the only way to do things.
I adopt Jumps’4 statement: *“The way I did it”*.
On the other hand, if you wish to follow my mods, there is no guarantee that the board you have (or will buy) would be the same design as mine!

*WARNING!*
The modifications deal with electricity and machines that can cause fire, injury or death if you treat them carelessly!


*MY APPROACH*

The way I have dealt with the matter “CNC my machine” was (is) a slow one. It started years ago and has gone long way since. I’m a hobbyist and I enjoy doing things “driving in the slow lane” gaining knowledge and experience all the way.

There is a Greek poem named “Ithaka” that describes my approach:

When you set out for Ithaka ask that your way be long, full of adventure, full of instruction.
.....
Your arrival there is what you are destined for.
But don't in the least hurry the journey.
Better it last for years,
so that when you reach the island you are old,
rich with all you have gained on the way,
not expecting Ithaka to give you wealth.
....
So wise you have become, of such experience,
that already you'll have understood what these Ithakas mean.
(Constantine P. Cavafy 1863-1933)​----------------------------------------------------------------------

Aiming to CNC my Sieg Super X2 Plus solid column mill I started almost two years ago to buy parts from e-bay. The first think I bought was a TB6560 3 Axis CNC 3.5A Stepper Motor Driver Controller Board and three NEMA 23 motors 175 Oz/in, 2.8A, 2.5mH (marked as 57BYGH56-401A).

As soon the board arrived I decided to test it and powered it up using a 12 volts computer PSU. The result was instant SMOKE coming from all 3 ICs on the board. When I complained to the supplier he replaced it instantly for a new one without asking any questions (??) or to send the board back.

This instant blow up of the board and the “very friendly” attitude of the seller to replace the board (without even opening a case at e-bay) made me suspicious and when the new one arrived I never connected it to the power supply but I started seeking information on those boards.

After reading many posts at other forums, studied the Toshiba TB6560 datasheet carefully and experimenting for more than a year with the board, I am convinced that this board is a poor design that needs some serious modifications to work as it should.


*THE 3 AXES TB6560AHQ BOARD 




PROS*

It is cheap (less than $ 50)
it can drive stepper motors up to 3Amps
It can handle up to 34 volts for the stepper motors.

*CONS*
There is no schematic for the circuit (some people created a schematic through reverse engineering though)
There is no true user manual (the one supplied is written in chinglish)
The designers violated most of chip manufacturers suggestions

_Dealing with it could be very educational in terms of electronics principles and applications, but *can give you many disappointments* and could bring out very bad attitudes and behaviours towards other people and materials around you._

*Why I chose to deal with it?*
First of all I found myself possessing two of them boards (after the supplier replaced the broken one for free and after I have changed the ICs for $9 on the broken one)
Second, I love challenges (this one drove me to my limits though), and I love designing and fixing things
Third, I intent to use it for hobby reasons and I cannot afford a serious controller (like a Gecko one)
Fourth, every machine I bought “made in China” needed minor or major mods to operate as it should. Why this board should be an exception?

So I decided to try and make it work like it should.

*ESSENTIAL MODIFICATIONS LIST:*

*1.* *NEVER power up the unit without motors connected to the outputs* and do not unplug a motor when the board is powered up. The poor grounding (note2) may destroy the 6560 chips.
*2. Ground the heat sink* for each TB6560 through its mounting screws. In the current design, there is a danger of blowing all chips if one goes bad. Adding the grounds helps protect them all.
*3.* *Disconnect the current reduction feature*. This generates extra pulses and is not useful.  
*4.* Pin 7 on driver chip has a cap that sets the internal frequency. *Replace the 1000pf* capacitor which is installed with a smaller value capacitor (150 to 330 pF).
*5.* *Clean up the pulse to Clock* (Step) and Direction signals. The pulse coming from the computer through the optocouplers is very slow on rise time (because of the optocouplers). The chip misinterprets the signals and misses steps. Bypass optocouplers.
*6.* The way the ICs are getting power violates the manufacturers guidelines for power up and power down sequence. *Do not use a single switch on the power line* coming from the power supply. Either power the ICs on/off by a separate power supply or use a dedicated powerup/down circuit to deal with the sequence matter.

*Step 2 GROUNDING HEAT SINKS OF TB6560AHQ CHIPS:
*
Heat sink Connected to pin 15 through the screw. The heat sink not being connected to GND.
The best way would be to connect a lead from one screw of every driver to the corresponding ground Pin 10 or/and 15 but NOT pin 6 (this is the 5V-GND - it should not be disturbed by additional driver currents!)




*Step 3 CURRENT REDUCTION CIRCUIT REMOVAL: *

Many people have disabled the “clever current reduction circuit” (which can't be that clever, as apparently it doesn't work well), a resistor a transistor and the capacitor that form the circuit have been removed. Resistor is silkscreened 4.7K. Transistor is further, on same trace and capacitor is connected to transistor.




*Step 4 CHANGING THE OSCILLATOR FREQUENCY:*

I have replaced capacitors on pin7 (silkscreened 102, i.e. 1000pF) with 3 smd capacitors salvaged from an old PC motherboard marked KE2 (i.e 150 pF). Toshiba recommends 100 to 3300 pF. The original 1000pf capacitor was putting the chopper frequency into the 40kHz region (330pf => 130kHz, 150pF ≈> 140kHz)




Toshiba notes at the TB6560 datasheet (p. 10)




*
Step 5 BYPASSING THE OPTOCOUPLERS:*


*SHARP PC817* optocouplers have a *very slow response rate* so they distort the incoming signals from the computer and allow system noise to cause unstable driver circuit operation.


According the datasheet the response time is as follows:




Moreover the way the optocouplers are in the circuit they provide no realistic isolation between the parallel port and the board so I don't see the point to use them. To solve the problems they create, I chose to bypass them.







*
Step 6 MAKING POWER DELAY ON & OFF CIRCUIT TO CONNECT IT TO THE BOARD*


*The 6560, according to the manufacturer (Toshiba) requires to get* *the 5V first and later it will accept the motor voltage*

*

*

On my board the 6560 driver ICs are getting 12v and 5 v from the motor supply through 12 and 5v regulators respectively. This is a poor design as  the 1*2V and 5 V regulators along with their capacitors perform a delay line for the 5V supply*. It takes some milliseconds until the 5V is stable on the 6560 drivers. On the other hand, the Motor supply is directed to the drivers instantly.





The transistors in the output driver are arranged in an *H-bridge*. It is essential to GUARANTEE at every time that within one pole of the H there is only one single transistor switched on at a time. *This can not be done without the 5v being stable on the driver!* So it is very probable that the too early voltage for the motor drive will open both transistors by itself and a short circuit will occur.




*An extra problem seems to be if a motor output is not connected*. My first 3 channel board was not connected  to any motors. Thus all 3 ICs  were blown instantly. *This was promoted by the heat sink not being connected to GND.*

*DO NOT OPERATE YOUR BOARD WITH OPEN MOTOR TERMINALS*. Connect spare motors or corresponding power resistors.


*My design of a delay on & off circuit*




This circuit is designed to operate as follows:

When Switch S1 is turned to ON position, it turns 5V on instantly and gives a 2 sec delay to 30V power to the chip and when S1 is switched OFF it turns 30V off instantly and turns off 5V after 2 seconds.

The circuit was constructed on the following stripboard for simplicity and ease of construction.
I have tested it and it works so far flawlessly.






After all these mods the board operates normally and there are no missing steps.

Thanks for reading this


Petros


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## PT. Johansen

I think it is in order with some acknowledgement of a good effort.

From my personal experience, the TB6560 IC itself isn’t nearly as bad a stepper controller as the internet seems to consider it.
It is certainly not super high quality, nor is it utter garbage.
I deem this reputation to originate from the various iterations of chinese craptacular cheap implementations.
All of them easily available from different vendors.
These boards usually claim specifications wildly exceeding components.

About 4 years ago I “invested” in the former TB6550 board version. At the time, well knowing that the design is ehm…. Doubtful to say the least. However, it only cost half of everything else, and being somewhat wellfounded in electronics, it was a project.

At the time I identified the same shortcomings as you have done, and rectified them in a similar manner. 
I replaced the optocpuplers and isolated them properly. I separated the logic 5v and 12V supplies, and disconnected the “power saving” feature.

As of today, after 300+ working hours, it still functions without a problem. It has never missed a single step. Any problems I have encountered have always been mechanical or operator related.

What surprises me is that the “PCB designers” haven’t even bothered to rectify these errors during the last 4 years.


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## petcnc

Well P.T. Johansen I think what we call "Mass Prodution" might be the cause of no rectification. Imagine an order of  100.000 PCBs ordered (based on this particular design) to keep costs low. Until they run out of all of them the design should remain the same.
I agree to your points! Since you fix the board it is working ok. Simple and reliable (!) board but with some modification needed.


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## SEK_22Hornet

Nice work! As for changes to the board layout, keep in mind also that these boards are basically  just "copies" of someone else design work, so changes to the circuit are not likely to happen.


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## petcnc

I cannot imagine that the original designer was that incapable to design it properly but somebody else copy it and made a best seller out of it.
I think we should start and design circuits! No matter how bad they are, there would be always someone in far east that can copy it and sell it.
Good perspective eh?


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## PT. Johansen

petcnc said:


> I cannot imagine that the original designer was that incapable to design it properly but somebody else copy it and made a best seller out of it.




You would be surprised how many lacking PCB designs are out there.
In my previous job I did a fair deal of PCB design reviews; I did see quite a few horrible mistakes. Thankfully nearly all cases are oversights, not intentionally. Most often such mistakes result in utterly unusable PCB’s, in other cases it will work, but not in a reliable or “safe” fashion.
I deem the TB6560 board derivatives to reside in the latter category. Often the layout and schematic work is carried out by different people, resulting in more mistakes.
In any case they should not pass through the quality assurance department, but herein lies the issue there aren’t any.

The intention with the tb6550 boards aren't that bad, only the implementation. The design ideas are fine, with exception of the power saving feature at hold torque. This I can’t grasp why you would ever want in a multi axis mill/router/3d printer.
As Petcnc concluded, I have no doubt that the power up sequence violation, is what ultimately kills these boards. This is by far the worst mistake.

I consider the cheap TB6560 boards a kit that needs modification before use.


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## petcnc

PT. Johansen said:


> You would be surprised how many lacking PCB designs are out there.
> I consider the cheap TB6560 boards a kit that needs modification before use.


I would extend this statement:
 "a kit that needs modification before use as most Chinese no-name products"


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## markba633csi

Well done Petros, have been reading with much interest your comments and following your project.  One observation I might make: the chinese do not encourage individuality as a rule.  It is not in their culture.  They follow and copy but it is not proper to stand up and say "this is incorrect, it needs to be (improved, fixed, recalled, etc. your choice)".
They also cut corners whenever the boss is not looking (and sometimes when he is too) so the quality is all over the place.  It's very hard to imagine being an engineer there or even a production worker.  If you insist on producing a good design you might get taken out and shot! 
Anyway, great job on reverse-engineering the board.  And the mods to the mill too.
Mark S.
Mt. View, Ca
USA


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## petcnc

Mark,
Thank you for your kind words. 
I had frustrations and fun with the particular board in such a level that I feel that I have build it from scratch with my own hands. My intention, right from the beginning, was to eliminate frustrations and keep the fun. It is working reliably now for so long I dont wish to change it for a better board.
What I do not get is why after so long time and so many comments towards the problems to the particular board they never made all corrections needed and advertise the board as "version x reliable and guaranteed to do the job".
Might be our western culture that prevents us on see the way they think and act!
I dond understand them!

Petros
Thessaloniki, 
Greece


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## markba633csi

I'm impressed with your persistence. Industry needs people like you who can solve problems in a systematic way.
I used to do that kind of work (I'm disabled and retired now at age 61) and don't have a college degree, but some of the smartest people I ever met didn't have one either. 
All the folks here who are converting their machines are gaining valuable experience which is good to see.  It is not clear to me if there will be a rebirth of industrial activity in the USA, but many young people here have computer skills without many hardware skills and I think you need both.  
Mark Silva


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## petcnc

Hi Mark,
Thank you again, you are very kind. Well... believe it or not I'm a primary teacher working at a public school in Greece! I suppose that if I had proper gudance some 40 years ago when I was 15 (I'm 55 now) I could study electronics, engineering or something similar to have a career in industry. But you know some times you decide about your life and sometimes life decides for you! To cut a long story short I found myself to follow educational studies and to have electronics and engineering as a hobby all my life. I suppose if I was living in another (western) country I could have done many other things.
I enjoy both teaching and my hobby and  I hope I will spend more time doing and fixing things when I will be retired.

Regards
Petros


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## markba633csi

Ah Petros you are nearly my age after all! Now I see where your patience and wisdom originate- from the years LOL
Good luck to you..
MS


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## petcnc

markba633csi said:


> Ah Petros you are nearly my age after all! Now I see where your patience and wisdom originate- from the years LOL
> Good luck to you..
> MS



Good Luck to you as well wise man

I would give an arm and a leg to be 18 and stupid though.....


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## markba633csi

After reading your postings I am looking forward to building my own cnc machine. Keep us informed on your project too old man ha ha
Ms


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## petcnc

Any help I can give do not hesitate to ask! 
Do you own a mini mill?
Are you going to use the TB6560 board? if you are not feeling on a safe ground with electronics I would suggest for a few more dollars Wantai Stepper Motor Driver DQ542MA 50V 4.2A 128Micros. This will play as it should out of the box see for example here (no relation to the sellers or manufacturers).
I wish you to enjoy the trip in coverting the mill as I have enjoyed mine! See details here

Regards

Petros


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## markba633csi

No Petros I don't own a real mill yet- I haven't even begun to assemble a parts list either. Probably will use 3 separate driver units and linuxcnc but as far as what to put in between is completely up in the air.  I like the Precision Mathews PM-25 mill because it already has the brushless spindle motor and belt drive.  I am wary of Grizzly based on the many horror stories I have heard about quality and service.  Were we not just talking about chinese companies? 
I worked in electronics industry for many years so I'm comfortable.  Still a linux newbee however.  Don't have any CAD experience yet either.  A little AutoSketch, many moons ago.
Mark


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## petcnc

Well Mark, you are in the wonderful position of making the "need" list! That is the best part of the process! If you make educated decisions you save yourself a lot of head scratching and money! I do not have any experience with PM machinery, I heard many people happy though, especially with after sales support!
For CAD, I am very happy with Fusion360 from Autodesk. That is CAD & CAM and is absolutely free for hobbyists like us.
Petros


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## markba633csi

I like free, thanks for the good tip Petros, I will check it out
Mark


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## petcnc

markba633csi said:


> I like free, thanks for the good tip Petros, I will check it out
> Mark


Mark Free is always the cheapest option you can have!
How on earth I changed your name to Lawrence! He he he
Sorry for the mistake I have corrected it
Petros


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## markba633csi

No problem Ebeneezra LOL
MS


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## compsurge

I retrofitted the TB6560 board that my robotics team has to the recycler. I tried the CNCZone fix,  but the board had no change. It was not exactly the same as any of the boards I've seen in forums.

I didn't want to waste more time, so I picked up a Gikfun parallel port breakout ($20) and a SMAKN TB6600 driver ($15.50 x3) from Amazon to test out. It worked perfectly. No noise. No hot motor while sitting idle. Optical isolation properly done.

Avoid the TB6560 board. We have a new low-cost solution!


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## petcnc

Well campsurge your board sounds promising! 
But I've seen also quite a few problems with TB6600 boards see here and here.
The TB6600 boarsds seem to work but not without issues. The powerup and powerdown issue do not apply to the particular chip and as you mention they solved the opto-isolation issues, but talking from experience I still remain cautious of far east designs.
I could not find the schematic of the particular board you mention and I don't know if the issues found to similar designs are solved. If so then it is a fine (and cheap) board to use.

One thing that bothers me is the power dissipation of all these Toshiba chips (TBA 6560, TB6564, TB6600). 
According to Toshiba datasheet the TB6600 can handle 4.5 A and 42 Volts. If you do the maths 4.5X42 gives you an impressive *189WATTs* of power! 
But if you look carefully at data sheet the chip can dissipate *40 Watts only with an INFINITE HEATSINK* (there is no such thing).
That means for a regular heatsink it can dissipate circa half of that. 
If you do the maths for 42 volts it is less than 0.5 Amps of power.

That bothers me...


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## compsurge

It's not the TB6600 ebay board you are thinking of. Check it out on Amazon!

To be completely honest I don't know for sure if is even a TB6600. I shot some photos and video of the board so I'll share them. This was meant for 3A 270 oz-in steppers on a Taig mill, so I'd still get better drives for larger motors.


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## petcnc

compsurge said:


> It's not the TB6600 ebay board you are thinking of. Check it out on Amazon!
> 
> To be completely honest I don't know for sure if is even a TB6600. I shot some photos and video of the board so I'll share them. This was meant for 3A 270 oz-in steppers on a Taig mill, so I'd still get better drives for larger motors.



Well the ones in Amazon are:




And




I bet they are both TB6600.

On the other hand I like your statement "It's not the TB6600 ebay board you are thinking of"! I suspect they are the same thing with the ebay ones.
If you open it please post a photo.

Regards

Petros


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## compsurge

Will do! Thanks for the research as well.


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