Hi,
unfortunately the manual does not discuss the output circuits at all. There is no way of telling
whether they are open collector or totem pole types. If you can read the buffer ICs part number
that would tell you.
It may or may not interest you given that you have bought spares (are they that rubbishy that you need spares?) to have
a look at the Homann Designs MB02 that I use. If you download the manual you'll find Peter Homan has detailed how the outputs are
driven and you are not left to guess.
https://www.homanndesigns.com/index.php?main_page=product_info&cPath=54_22&products_id=59&zenid=11oq21v419cogk8bc3fiaoren1I have attached two pics using typical values that you might find in an open collector output BoB. The first shows sinking current. When the output transistor is
ON or conducting it sinks current from the stepper drive via the opto LED and the curent limit resistor. With 5V supplies the opto LED current is about
5 / 470 =10mA, easily enough to signal across the opto barrier. The second pic show the same BoB but sourcing current to the stepper driver.
When the output tranistor is OFF then the current flow from the 5V supply through the pullup resistor, thought the current limit resistor , through the opto LED
to 0V. The opto current is only 5 /(10000 +470) =0.5mA which is not really enough. Cheap stepper drive optos require 5-10mA to signal reliably.
I have probably, and deliberately, portrayed a worst case scenario to illustrate a potential problem. In absence of suitable documentation about
your BoBs outputs and your stepper driver inputs you can only guess. Unfortunately while these subtle details are often missed by documentation
what with the wide variance of design/manufacturing standards throughout the CNC world clashes of this type are common.
Unless you have some decent test gear and the knowledge to use it all you can do is guess.
Craig