[pa2262]

Greetings,
I'm hoping someone has had a similar experience with this problem and can offer some trouble shooting pointers.
My QT15 power chuck suddenly quit working for no apparent reason.
Operating the foot switch now results in only clicks and flicks of the pressure needle.
I started my process of elimination by disassembling and checking the foot switch and found that I have 24-25V on the 24V wire, which transfers through the switch when it's depressed.
Isolating the switch I get continuity every time I activate it. So I have concluded the switch is not at fault.

What's interesting is, when I switch from external to internal clamping or vice versa via the switch on the back door, the chuck opens and closes without hesitation.
So that tells me the basic hydraulic action is OK. The solenoids and the valve must be working or the chuck wouldn't move.

I also found a relay on the back door marked "CH", which I thought might mean "chuck" so I swapped that with another to see if that changed anything, which it didn't.

The other interesting thing is, I tried programing an M code to activate the chuck through single process operation, and it won't work.

That leaves me wondering about the possibility that a circuit board might have a failed circuit; but if that's the case, which board might that be ?

I do have a collection of boards I bought when trying to isolate other operational issues, I just need some suggestions on which board to swap out.

Thanks in advance for any replies

[pa2262]

Going further down this rabbit hole, I'm finding that I have 100VAC to only one side of the chuck valve solenoids.
Pressing the foot pedal will energize the one side. Pressing again, will deactivate the energized one but not energize the opposing one.
Looking at the relays on the back door while working the foot pedal revealed a relay marked UCH that is activated by pedal pressing.
Swapping this relay with another did not change anything.
So, I'm missing voltage to one side of my of solenoid valve. I'm still suspecting a problem on a board, but again... which one ??