AXBB charge pump fault

[john swift]

The reference to " other isolated outputs are all capable of driving the relay "

differentiates the outputs from the 5V logic level outputs that you connect to other logic gates or the stepper driver step & direction inputs

from the open drain outputs designed to switch inductive loads like the relays

As an example
Going back to equipment I used and maintained in the eighties
all the logic was built from 7400 series TTL logic

Typical gate inputs passed 1.6 mA when an input a input was grounded
and the outputs could sink 16 mA
so you could only connect 10 inputs to the output of an IC
unless you used a buffer that could pass more current

To connect to other devices like tally lights for the control panel switches

A lamp “driver” / BCD decoder like the 7445 switched 28v bulbs ( run off a 24V supply ) by grounding the other end of the bulbs filament

The 74141 being another version with high voltage outputs for driving Nixie tubes
(which is basically a neon with an anode connected to 180V DC via a resistor and 10 cathodes shaped in the form of the digits 0 to 9 that glows when grounded )

These days you would use a 7447 BCD to 7 segment decoder driver connected to a 7 segment LED display or LCD

John

[john swift]

It looks like the FET for output 1 has short circuited

I would check you don't have a wiring problem that could connect the 24V DC to the AXBB output

Did you check the relays coil resistance is 650 ohms as expected
less than 48 ohms would pass more than the 500mA limit for the output

John