Issues with Instant Setback on pace ST50 intelliheat (doesn't seem to work)

[eeBright]

Hi everyone,
I've recently lost the stand and handle for my pace ST50 soldering iron. It was enough for me to do occasional repair around the house, so I've decided to simply buy the new replacement parts.
While at it, I've bought the stand with instant set back capability as my ST50 seem to support it (has a port for it).
Since then, I've never been able to get the functionality working, and went as far as removing the front cover and checking the DC voltage at the PCB connector to verify 5V while tip is loose and GNDed signal while in the stand.
I've also took the stand apart to verify that ISB switch uses only two lines (signal and GND) and connectivity (while off) from the switch to the PCB connector inside (less than 5 Ohms).
I have the software setback set to lowest (1 = 10 min) and have waited up to 2 minutes for the ISB to kick in. Is my ST50 broken (works seemingly well besides ISB functionality), or am I missing something?

If needed, I've bought the TD-100A 6993-0319-P1 bundle and trying to use it with older ST50 interlliheat. It doesn't mention anything about not being ST50 compatible, and simplicity of control would indicate that it should work.

Thanks for all the fish.

[PlainName]

Try setting the temperature setback to 0 (that is, off). If you enable it then it might override the stand input - with the stand input you don't need to have auto-setback at all.

[eeBright]

You sir are a genius!!! With software setback disabled, ISB turns the heater off in 30 seconds. This has been me nuts as I couldn't find the info on this in any manual.

Thank you!!! 

[PlainName]

Fortuitous timing. Just had exactly this with a Weller setup