A Axis 164 Drive Fault error. chasing a week. MoCon or I/O? A Brk check?

New setup for the Son and I. No clue if or when the A axis worked last. 20 year old 98 VF/4. all brushless drives. Running a BRUSH 210 w/ inductor to go brushless to brush HRT.

I am unable to get past this A Axis 164 drive fault error. I have swapped everything but the MoCon and I/O boards. I have moved everything up to "B" Axis slots, and set the A Axis to disabled- And it works as B. I hate to go into a MoCon board for those types of costs as I do see the A brake circuit does come in from I/O board. I guess I should check that somehow. (voltage transition low to high or high to low on the red A BRK wire of harness I assume). I do here the air puff on A. but am not sure if that is part of the brake release? I do get an A UNCMP on the screen, but cannot be sure it's firing. It's almost immediate. If I cycle it 20x... get it all warmed up.. sometimes ithe 210 platter starts to turn while it tries to home- Then error after running 20- 30secs.

Just wondering if the brake did not unlock, would the current to turn Max out and cause a 164 fault? Just chasing any leads at this point.

Is there a secondary alarm? ( I.E., 992, 993, etc... )

I was going to ask if you swapped the current control cable, but you state that it works fine as a B axis. Sure would seem to indicate that it is on the MOCON. One thing I have experienced in the past is a wonky connection at the edge of the board, where the encoder plugs in. Do yourself the favor of cleaning, inspecting, ensuring the connection, there. Yes, I know it is an encoder connection. However, I have seen unrelated errors originate from a bad connection there.

Good luck.

Thanks- Where is that encoder connection? I recall reading a little bit about that? So new here. Old Aerospace guy.. so all the "stuff" is fine, I just do not know the system well yet. But picking along. Here is an update:

I will try to help this along. I have had some folks asking about what the Haas brushless to brush really means.
To run a brush hrt from a brushless amp- You must purchase 1 of 2 optional kits which allow brush hrt operation from a brushless amp. (and end up w/ the 1 17pin DIN connector).

1 of those kits is far more expensive than the other (see my post from a few weeks back)... To see a picture of the 93-4303 ($395) 4th drive pre-wire kit (with inductor) take a look here: https://www.haascnc.com/productivity...html#gsc.tab=0 The inductor (looksl like a transformer) are used to end up w/ an HRT BRUSH compatible motor voltage.

So here is what I did.....
I put in the new Amp. Wired that in for the 4th A axis. Same error. A axis 164 drive fault.
I even swapped the 17pin DIN connector. I put in another all-new cable. - Same Error. A axis 164 drive fault.

Isolation time: Move entire 4th axis to 5th axis slots.... Does it follow 4th to 5th???
I moved the 17pin DIN to MoCon (left side) connect to the B (5th Axis) connector.
I moved the AMP to MoCon cable (right side) to the 5th axis connector.
I moved the A brk (P29) to B Brk, (P44) on the I/O board.
Enable 5th axis as a 210.
Disable 4th axis.
power up- It does run fine.
Compared the B Side parms to A side. same.
Conclusion: The problem is either in the MoCon or the I/O board & 4th axis A-Brake circuity. (or could it be in either of the 2 boards behind the moCon? New to Haas!).
Since I think it'll be the MoCon- But before I drop a a grand or more on a MoCon swap... I should validate the ABrake is triggering from the I/O board. (I assume).... just to validate the 4th brake and 5th brake act the same?

SOLVED- I went w/ the Rip & Replace method. 20 year old machine. I had at least 2 bad parts. Replaced the Amp, the Amp to MoCon cable, the inductor board. also rewired all the connectors w/ new wiring harnesses this is running fine.