Troubleshooting non responsive machine- Mach3/Syil x4

[Doddy]

First thing - have you checked the integrity of the fuse, F1, on the board?

Okay, I'm going to post a link to another site that has the schematic for a Syil 4 axis controller board - for no other reason that it will give a good idea of the pinouts of the IDC headers

https://www.cnczone.com/forums/syil-...lp-please.html

The pin bindings are clearly different from this BOB to the BOB on the Syil 4, so I cannot determine which pins on the IDCs are STEP and which are DIRECTION, but I can say that these are EITHER pin 1 or pin 3. Pin 2, 4 and 6 are set to +5V (so the step/dir will be driving the cathode of the opto-isolator on the stepper-drivers in the machine, low-side switching). Pin 5 confuses me - it's a common pin across all axis connected to a 3-pin connector on the 4-axis schematic... possibly an Enable signal to the stepper drivers. Now, I would ask for an image of where ONE of the three ribbons plugs into on the other end - Im expecting into another PCB or a module, and I'd be particularly interested any marking/engraving. ...ah, you've posted already. So you could perform the original tests against both pin-1 and again against pin-3 on the IDCs - one should behave as expected, the other won't.

But, now we know more about your pin mapping and an awful lot more about your BOB, I'd be keen to change from looking at motors and more against the e-stop. It's easier to apply some logical diagnostics against and understand the apparent total lack of interface with the PC.

So, starting again:-

1) Establish a supply ground (we know the BOB is AC driven with onboard rectifier/regulator), so we need a signal ground. You've suggested that you have already measured board supplies etc - do you have a DC ground available to you?, I'll assume you have - you can pick one off the GND on the spindle connector, the centre pin on the 3-pin TO220 packaged regulator, or the "-" pin on the chunky capacitor.
2) Establish which is the signal wire on the ESTOP input to the BOB - measure between either wired input on ESTOP and ground, with the ESTOP activated, and not activated. One of the pins should be consistently 0V (according to that schematic), and the other should switch between 0V and 5V depending on the ESTOP button position. Confirm this.
3) with the IDC ribbon to the DB25 connector for the parallel port on the Syil connected to the board, but with the parallel printer cable disconnected, then I'd measure the voltage from 0V to pin 11 on the parallel port connector on the Syil. Confirm that this changes from 0 to 5 or vice-versa on the actuation/release of the E-Stop.
4) Connect the printer cable from the Syil to the PC. Confirm the behaviour of the Estop control within Mach3.