Opto-Isolator problem G201 ?

[Clyde]

Hi all, been a while since I've been on cnczone........

I am trying to troubleshoot my Z axis.

I built the machine a few years ago.....used only from time to time (once a month?)
I am using it more often now (daily). Everything worked great while trying to design my cabinet drawer fronts. I routed designs in 2 draw fronts out of cherry wood (after doing several tests/changes in mdf first) and they looked good to me (but not to my wife so I made a final mod and GROWL, down into the wood the bit goes!!!!!!!!!

The Z axis only moves in one direction (down) no matter what I tell it (in Mach2 MDI or trackball).

I'm using Mach2 6.11, homemade BOB,
3 Gecko G201's
PK266-E2.0B's wired bipolar parallel,
G201's rigged for 2.66 amps,
~48v powersupply @ 10amp.
Windows XP sp2 on a 2.8ghz Intel P4, (NO internet connection).

I have tested the BOB using PARMON and all seems well with it.
I have tested for continuity on the Z axis power cables (from G201 to motor)
I have exchanged the y and z axis cables at the motors (have mollex connectors at motors) and the problem follows.
I have tested the dir pins at the Z axis G201 (Drive Power Off) and it follows Mach2's command (0v, -5v [with DMM common to G201 common]) depending on the direction +Z or -Z

Could it be the HCPL-2531 opto-isolator in the Z axis G201?


I have searched cnczone for opto-isolator and the like and did not find that the G201's have had this problem with others, is this so?

[Clyde]

I ran another test today.

I switched the 2531's between the Y and Z G201's.

The problem moved from the Z to the Y axis...............Yep, that's it.

Glad I ordered 10 512-HCPL-2531's yesterday just in case.


P.S. makes me a bit nervous now, since I don't have all that many hours on them.

[jcdillin]

That is strange because I had to replace one of mine the other day on my 201. Mine was strange because it would work sometimes and then all of a sudden stop and just shudder.

Popped in the new isolator and all is well.

[Clyde]

I replaced the bad opto-isolator in the Y axis (Z opto moved to Y during last test).

It went both directions after the replacement, but missed steps.

I replaced the replacement (had bought 10) and it still was missing steps (and growling). I replaced bearings on either end of the screw drive, because it sounded like a bad bearing, even though I could not believe a bearing would wait and go out right then just to make my day miserable.

Nope, still missing steps and growling.

Set the pulse width in the motor tuning to 4 us, works fine now.

hmmmmm, could the 512 in front of the 512-HCPL-2531 mean it is only good to 512k instead of 1024k (1mhz)?

[jcdillin]

Yeah probably, the units I bought said they were good up to 1MBIT