Novamill - spindle PWM ?

[DavidJ]

I recently bought a Novamill. Current plan is to control it using LinuxCNC - I'd like to use the existing electronics as much as possible (and have the option to revert to original). From other threads I've found details of how to wire to the 96 way header on the controller base board for STEP/DIR. [ But see later]

Has anyone successfully identified which pin on the header carries the spindle speed PWM signal ?

Spindle Go Relay output - Output for this is output 0, which I understand has Darlington Driver on the top board (to be removed) - I presume I'll either have to add a driver device to my circuit, or utilise one of the outputs from 8-15 with driver on bottom board?

The controller looks closest to the Nextmove ST (but maybe doesn't quite match in all respects, perhaps an intermediate build ?) - I'm assuming STEP/DIR pins will be same on header as for earlier variants. [EDIT - top card matches description for Denstep ]

Machine details (from control box)
Novamill S/N 81209C
MARCH 1999
Electrics SN 0020??54 Software 2.102 (2 characters defaced)
ESMint 3.28 v1.6H/S-JDS
Bottom board BALDOR Optimised control F391 issue 2

Any hints or guidance appreciated.

Thanks in advance