[joefishellis]

Great thread, have found it really useful as a point of reference. I am doing a similar conversion although I am attempting to use GeckoDrive G320X servo drives connecting to the orgiginal Parvex RX320ER1026 motors and Renco 77676-051 encoders, the problem I am having is the G320 is not seeing any signal from the Renco encoder, I have had an oscillioscope on the encoder output and I cant see any signal, I am feeding the encoder 5v and i have tried grounding it to pin 9 of the diagram on page 1 and also chassis ground.

only thing I can think to do to try next is ground the negative channel A and B.. although dont want to damage the encoder.

I am getting no sag on 5v input so dont think there is too much current demand from the G320X to encoder??

Any help would be gratefully received

[Todd Zuercher]

I was never very impressed by the wiring arrangement on the 408. There is simply a big loop of cable under the table that gets drug back and forth, with no cable chain to support and protect the cables. The result is the cables often end up just dragging on the ground and are prone to wearing out. When you are testing your encoders are you testing though the original wiring? Make sure all of your wiring is good and none of the leads are shorting to ground. A dead short to ground is the quickest way to kill an encoder.
(PS both of our Sabres are still running the original Gerber controls. But if I were to retrofit them it would be to Linuxcnc and keeping the original servo motors and Elmo drives.)

[joefishellis]

I was never very impressed by the wiring arrangement on the 408. There is simply a big loop of cable under the table that gets drug back and forth, with no cable chain to support and protect the cables. The result is the cables often end up just dragging on the ground and are prone to wearing out. When you are testing your encoders are you testing though the original wiring? Make sure all of your wiring is good and none of the leads are shorting to ground. A dead short to ground is the quickest way to kill an encoder.
(PS both of our Sabres are still running the original Gerber controls. But if I were to retrofit them it would be to Linuxcnc and keeping the original servo motors and Elmo drives.)

See what you mean about the cables being dragged around. I may fit a cable chain when finished the rest of the work.

I have a fully working 404 machine but want to modernise the control software, I have used Linux CNC and quite liked it, I bought mach 4 but found it overly convoluted in its configuration (bad UX design and too many paths to related configuration elements when using the smoothstepper) I do however whole heartedly recommend UCCNC with an AXBB-E board and touch screen.

I do want to keep as much of the Sabre intact as I can but as I understand it the ELMO drive amplifier requires an analogue input (not pulse - direction) which is why I have chosen to use the Geckodrives G320X as they will interface with the AXBB-E.

Currently the Y motor and the short cable loom is remover/separated from the enclosure and on my bench, the G320X is in test mode and its not seeing the pulses from the encoder, I have connected my Tek oscilloscope and cant see any signal coming from the encoder so at a guess its something to to with the power or ground to the encoder? (the 5v hasn't sagged ... so thinking about it is prob ground related).. are we sure the ground pin is correct on the diagram on page one1 and it doesnt connect to shield? I'll check in morning as found this elswhere on internet https://encoder.co.uk/core/files/enc...iles/TB532.pdf which shows the Renco wire colours that are visible when removing the encoder cover, I'll buzz out the black wire back to the encoder ground.

[Todd Zuercher]

I do want to keep as much of the Sabre intact as I can but as I understand it the ELMO drive amplifier requires an analogue input (not pulse - direction)https://encoder.co.uk/core/files/enc...iles/TB532.pdf which shows the Renco wire colours that are visible when removing the encoder cover, I'll buzz out the black wire back to the encoder ground.

That is one of Linuxcnc's best features. It works perfectly well with old analog servo amps. (In fact I prefer the analog control to step/dir commands.)

Glad you figured out your encoder problem. Hopefully only using them single ended on the 320x doesn't cause you too many problems.

[joefishellis]

I think you have a good point Tod, perhaps iLinuxCNC might of been the most elegant solution in this case. I am bit to far down the road with UCCNC now so will persevere, but will bear LinuxCNC in mind if I do up another system with analogue drivers.

[fdarling]

... But if I were to retrofit them it would be to Linuxcnc and keeping the original servo motors and Elmo drives.)

Hello Todd, we've spoken before about your ballscrew mod. I have retrofit several Gerber Sabres to LinuxCNC, and I finally came out with my drop-in replacement motherboard kit. It allows you to not only keep the machine as-is, but allows for expansion: after-market servo/stepper drives, I/O or pendant expansion via SmartSerial, and both tool setting and work touch-off probe inputs.

You can find out more about on this thread here:
https://forum.linuxcnc.org/39-pnccon...tart=20#294504

That being said, if you do want old "stock" motherboards, I am working up a collection and have no use for them