KX3 Spindle Problem

[Doddy]

looks to me like there's a group of 3 capacitors near the center of the board and the middle one looks like it's blown.?

Pfft, you have better eyes than me.

I did google the KX3 when Ken first posted - I think I agree with the C11 board and this was the original spec for the machine so a like-for-like replacement at the time? A new card is (only?) $68 and if OP has the confidence to replace then it might be the easiest solution all around. The chip that's going to be responsible for the analogue output is the LM<something-or-other> on the far left of the photo. That's likely a £1 replacement, though it could be with the ancillary circuitry around there (caps, resistors) or the opto-isolator (the white chip), or the power from the spindle-controller card (I'd expect that to export 12Vdc to the BOB for the purpose of isolated power supply between the BoB logic and the spindle-controller) - worth checking that.

OP: If you find yourself in a rabbit hole with this (and I don't think you need to) if you're prepared to post the board I could always take a look to overhaul it. That's a casual offer - I think it'd be quicker/easier for you to contact CNC4PC in the first instance.


EDIT:

Just re-reading the thread, OP - if you have the 10V supply from the spindle board then try throwing a 10k potentiometer across this and the spindle 0V, with the wiper connected to the analogue input - that should give you full manual control of the spindle speed and verify that the spindle board is okay - just to confirm the BOB is suspect. (there's a chance of a fault on the spindle board dragging the analogue output from the BOB down - this just helps to isolate the problem).

[JAZZCNC]

(there's a chance of a fault on the spindle board dragging the analogue output from the BOB down - this just helps to isolate the problem).

This is why I said to disconnect the BOB from the spindle board when checking volatge so hopefully Ken did this.?

Also I'm not sure which Spindle board it's using but I know a lot of these spindle boards have mains voltage kicking around the Analog input so be careful Ken.!

[ModelSteamKen]

Thanks everyone for the comments. I have since put a question on CNC4PC forum and I await comments. It's looking very like the BOB. I'll post the result as it might be of interest to someone else.
Ken