Semco cnc mill problem

[Hood]

Should be 5v

 

[scottmk1]

Aye. Just going back through the connections to see if I can find where I'm losing the other 4V

 

[scottmk1]

OK so all 3 encoders are powered from the black and white wires at the back of the picture, they go to a junction and then the feeds run to each encoder.

 

[Pete.]

That servo seems to have a tachogenerator and an encoder fitted. The tachogenerator gives out 9.5v per 1000rpm so if it's not working or connected than something in the control might not be receiving the RPM signal.

Scott I have a couple of industrial encoders i'll dig one out and see if it might suit you for testing.

 

[Hood]

What voltage are you getting at the others?

 

[Hood]

That servo seems to have a tachogenerator and an encoder fitted. The tachogenerator gives out 9.5v per 1000rpm so if it's not working or connected than something in the control might not be receiving the RPM signal..

The tacho will go to the servo drive (amplifier) and unlikely it will go to the control so the control won't know or care about it. It will get the speed/direction info from the encoder. It could cause issues between motor and drive but the message on the control seems to suggest it is an encoder fault so..

 

[Pete.]

The tacho will go to the servo drive (amplifier) and unlikely it will go to the control so the control won't know or care about it. It will get the speed/direction info from the encoder. It could cause issues between motor and drive but the message on the control seems to suggest it is an encoder fault so..

Fair enough, what I know about it could fill a pin head. It just looks in one of the photos that the tachogen red wire is the one that's been re-soldered.

 

[scottmk1]

What voltage are you getting at the others?

1V, that's all the power supply is giving.

 

[scottmk1]

@Pete. They haven't been soldered, if you mean the yellow bit on the wiring that's just ID tags

 

[Hood]

Disconnect the z encoder plug and see if it is still just 1v.
Do the other motors run fine or is it not getting past the z issue?

 

[scottmk1]

Disconnect the z encoder plug and see if it is still just 1v.
Do the other motors run fine or is it not getting past the z issue?

I've got the Z axis completely disconnected and the other 2 axis are working with no problems. Still 1V at the outlet of the supply.

 

[Hood]

Weird, sure your meter is OK?

 

[scottmk1]

Weird, sure your meter is OK?

Definitely I've tried two different meters and they are both giving me 1V at the outlet of the power supply

 

[Hood]

What do you get if you disconnect all the wires from the output?

 

[m_c]

Just to clarify, the other axes jog correctly?

(I just want to clarify, as even though you're only getting a Z axis fault, it will likely be the first one to initialise, so will fault first, and faults on the other axes may not get triggered even though they are also faulty)

 

[scottmk1]

The same on the pins it's connected to at present. The pins at the opposite end have 5.5V across them though, reckon I should try those?

 

[scottmk1]

Just to clarify, the other axes jog correctly?

(I just want to clarify, as even though you're only getting a Z axis fault, it will likely be the first one to initialise, so will fault first, and faults on the other axes may not get triggered even though they are also faulty)

Yes the others are working fine, from the mpg and on manual mode. They don't give any alarms

 

[Hood]

It could be possible the other encoders are happy with 1v and it is the power supply that is the issue but I would find that unlikely, if it had been 3v I could have seen it.
Certainly worth a try I would think, the encoders are 5v supply so 5.5v shouldn't harm them. Might be worth just doing the Z though just in case.

 

[scottmk1]

OK tried that and with the voltage drops to 1.3V across those pins with the Z axis connected, both the others disconnected

 

[Hood]

Sounds like the power supply may be knackered but strange how X and Y are working.
If you have a 3x AA batteries you could series connect them and connect to the Z encoder and see if it works.