( Solved ) Mesa 7i76 encoder problem

PCW wrote: The spindle speed is not affected by Z, only A of B
Can you check the input-a, input-b and input-index pins in hal?

Ok in halshow
A does not change
B does

so I moved the B TB-3 pin 10 to pin 7 A and A to B

result :
A does not change
B does
to me it looks like the A pin 7 is faulty.

Is the spindle encoder cable shielded and grounded on the Mesa side? Not both sides.

I would heck the cables, this might also be a cable/5I25 issue
Also check the 7I76 jumpers and make sure they are all set for TTL mode.
The 26LS32 parts used for the encoder interfacing are pretty rugged
so I would not expect a failure there. You might also do a physical inspection
of the 7I76 for any obvious issues.

tommylight wrote: Is the spindle encoder cable shielded and grounded on the Mesa side? Not both sides.

No its not shielded but has been in use for a few years the encoder is just a simple 64 slot disc with simple slot type sensors

I can see the square wave on A,B, and Z with a O/scope at the pins on the mesa card

PCW wrote: I would heck the cables, this might also be a cable/5I25 issue
Also check the 7I76 jumpers and make sure they are all set for TTL mode.
The 26LS32 parts used for the encoder interfacing are pretty rugged
so I would not expect a failure there. You might also do a physical inspection
of the 7I76 for any obvious issues.

I will re seat the 5i25 and also the cable to the 7i76 that cable is full screened and only about 500mm long.

As I said to Tom: The encoder is just a simple 64 slot disc with simple slot type sensors

I can see the square wave on A,B, and Z with a O/scope at the pins on the mesa card

Clive S wrote:

tommylight wrote: Is the spindle encoder cable shielded and grounded on the Mesa side? Not both sides.

No its not shielded but has been in use for a few years the encoder is just a simple 64 slot disc with simple slot type sensors

I can see the square wave on A,B, and Z with a O/scope at the pins on the mesa card

It should be shielded as any interference from the spindle motor, be it from quick direction change or braking or fast deceleration can induce enough EMF to fry the inputs on the Mesa card, especially if it manages to induce negative potential. The encoder/sensor will not be affected by this.

tommylight wrote:

Clive S wrote:

tommylight wrote: Is the spindle encoder cable shielded and grounded on the Mesa side? Not both sides.

No its not shielded but has been in use for a few years the encoder is just a simple 64 slot disc with simple slot type sensors

I can see the square wave on A,B, and Z with a O/scope at the pins on the mesa card

It should be shielded as any interference from the spindle motor, be it from quick direction change or braking or fast deceleration can induce enough EMF to fry the inputs on the Mesa card, especially if it manages to induce negative potential. The encoder/sensor will not be affected by this.

This is just a simple single phase 230v AV motor no VFD no change in direction just forward and no braking

Clive S wrote:

PCW wrote: I would heck the cables, this might also be a cable/5I25 issue
Also check the 7I76 jumpers and make sure they are all set for TTL mode.
The 26LS32 parts used for the encoder interfacing are pretty rugged
so I would not expect a failure there. You might also do a physical inspection
of the 7I76 for any obvious issues.

I will re seat the 5i25 and also the cable to the 7i76 that cable is full screened and only about 500mm long.

As I said to Tom: The encoder is just a simple 64 slot disc with simple slot type sensors

I can see the square wave on A,B, and Z with a O/scope at the pins on the mesa card

I have re seated the 5i25 and 25DB connections. The B channel in halshow changes state but not the A channel.

As I stated above swapping the cables from A to B the B channel still change state.

I am using the other software encoder pins for two mpg's 16,17,18,19

PCW wrote: I would heck the cables, this might also be a cable/5I25 issue
Also check the 7I76 jumpers and make sure they are all set for TTL mode.
The 26LS32 parts used for the encoder interfacing are pretty rugged
so I would not expect a failure there. You might also do a physical inspection
of the 7I76 for any obvious issues.

I setup a 7i76e and made a config with pnfconfig then I just moved the encoder plug from the 7i76 and put it in the 7i76e just with 5V power connected.

A and Z now worked as expected including a simulated thread on screen. stopping the spindle the z stops etc

So it looks like a problem with the 7i76 board perhaps dry joint or the 26LS32 !!
Is there a work around?

It could also be a 5I25 or cable problem