7i76e - TB2 not working - no axis motor movement - but TB3 and rest working fine

Hello,
yesterday i have make some wiring differently on my Lathe, so that the wires are not visible.
I did not change anything on the board wiring, everything has been done without power on.
I actually just changed the 380v wiring and after i powered on the machine the X and Z motor did not move.

To make it as short as possible: I tested one motor to all 3 stepper slots on TB2, but nothing changed. I went out of my workshop and wanted to start a thread here in the forum, but then i thought i check if the last stepper slot which is on TB3 works. So i went to my workshop, put one motor to TB3 stepper slot and it works.

So, something with the TB2 terminal is wrong. I am not sure if its broken or if it can be something with the firmware?

If you know how i can check if its 100% a hardware fault, then please let me know how to check that.

I really havent done nothing on the wiring while the power was plugged in. Not only that it would be very stupid, but i also already damaged ones by 7i76e, by unplugging the 24v, but on the DC side, which i learned should never be done that way. That damaged my outputs but got reparied with a new chip by my one friend.
No i dont know what could cause a damage on TB2?

Thanks in advance for your help.

The first 4 stepgens on TB2 are driven by a pair of chips. Its likely one
or both have been damaged somehow. This can happen if any of the TB2
Step/Dir pins accidentally contacted something with a voltage outside
of the 0 to 5V range.

@PCW: Thanks for your quick reply and the explanation.
I have 2 questions:

1.Can you show me on that picture (store.mesanet.com/image/cache/catalog/Pr...i76ecolo-500x500.png) which pair of chips are broken? Below TB2 and above TB2 are a pair of chips, so i dont know which are broken:

2.I would need only one more stepper slot for the second axis, because TB3 works, so my question is, which outputs i could?

U12 drives the - outputs
U19 drives the + outputs

It may be only one is damaged so you may be able to get it operational
by rewiring the drives to only use the + or - outputs

Thank you very much.
Actually i dont know how to get it operational by rewiring the drives to only use + or - outputs, so i would like to replace the chips.

The chips have this code: ACT 540 and the other chip ACT 541

I could found those chips but i am not sure if that are the correct one:
Farnell page link: chip :CD74AC541M
CD74AC540M

It would be nice if you could help me with that and i will order them and give the card and the chips to my friend who will replace them

Thank you very much already PCW

Thats the wrong package, you need the TSSOP package not SOIC

hmm i will try to find it, but thank you for pointing me in the right direction

I think what PCW mean to rewire to use step+/dir+ and common negative or step-/dir- and common positive its easy to do.
Gecko 201x is wired this way, usually i wire this way at PLC too or I misunderstood PCW and he told another thing

Thanks Himarc3d for your message.
Unfortunately i currently dont know how to get it done, but i got on yesterday my Multifix and would like to get the first important parts done on my lathe to get the multifix mounted soon, but for now it seems that i have to order the chips to repair the card. On tomorrow of course i will think how i can get both motors to work without repairing the card, but still i would like to repair it, just because i will feel better with it

Can't u use a multimeter or a simple resistor-led to control on every pin if there are toggles when you expect a motor move. Try once against gnd and once against 5V. So you might find pins that still work and you can survive till replace...
Mike