KX3 Spindle Problem

[ModelSteamKen]

Hi Jaz
Yes the 0-10v comes from the BOB in the right hand side electrical compartment and then goes to the DC spindle control board in the rear compartment. All the works are as the standard Sieg KX3. I'll take some photos and post them to-morrow.
Thanks
Ken

[JAZZCNC]

Hi Jaz
Yes the 0-10v comes from the BOB in the right hand side electrical compartment and then goes to the DC spindle control board in the rear compartment. All the works are as the standard Sieg KX3. I'll take some photos and post them to-morrow.
Thanks
Ken

Ok well that's simple enough to check. Disconnect the wires going to the Spindle control board and measure the voltage at commanded speeds. If you haven't changed any of the Spindle settings in control software (mach3 I presume) then you should get 10v at full commanded speed. If you don't then it's the BOB at fault not the spindle control board.
If you have changed the spindle settings then I can't help anymore without knowing the BOB your using, but Knowing John S it won't be anything too fancy as he liked to keep it simple and cheap.

[ModelSteamKen]

Hi Jazz
Having problems putting a photo on but have checked the voltage and only getting 3.9v at full command speed. All setting are at original settings.seems like it is probably is a BOB fault.There is an web site visible on the board www.cnc4pc.com. Any other suggestions as to a make of board.
Ken

[JAZZCNC]

Good old John S probably just saved you some money by fitting decent gear.?
I think that's old or should say, early C11 board.? If you notice the board is full of plug-in chips rather than surface mount like many cheaper boards use, this is done so can easily swap them out if one blows up.

Cnc4pc is owned and run by a guy called Arturo who's a very helpful guy so maybe worth dropping him an email. He'll tell you which chip you need and more than likely sell you one.

[JAZZCNC]

The picture isn't great but it 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.? I'm not into electronics but I'm pretty sure something like this would still allow to work but lower the voltage.? . . . I'm sure Doddy or some of the Electronic wizards will tell you quickly enough if it can.

It may be worth you taking it out and giving a close inspection.!

[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