Turbomolecular pump troubleshooting (EXT255H with EXDC80)

[Chris Giles]

Hi Arun,

that all sounds good. Are you sure that you have the pinout correct? For instance, try the 2 checks i mentioned before.

regards
Chris

[rhorst]

Looking at the photo of your power supply, it looks like it is connected incorrectly. That type of supply has floating + and - connections and a separate ground internally tied to the chassis but not to either voltage. You probably do not need any ground connection at all, but definitely need both + and - tied to whatever you are powering. Often, the negative and ground are externally strapped together because most devices use positive voltages for power and control.

You probably want to tie the negative and GND together and to the negative of the booster supply, and then tie the positive from the supply to the positive of the booster.

Without the negative terminal connection, you might be reading some correct voltages because leakage brings the negative terminal to the same potential as ground, but without that connection, it cannot deliver much current.

[Rex Allers]

I don't think we've seen a pic of connections since he got a different linear supply but I suspect it is ok. The DC-DC booster card is making 80 V out, so must have a reasonable input. All earlier pics seem to show a proper connection to the supply.

Have you ohmed the start switch to verify open/closed is good?

As Chris said, the measurements seem reasonable.

Arun, I think you said you got another of some portion of the turbo hardware. Was it the driver module, the turbo, or both?

I'm not seeing anything wrong in the configuration, except not working. When start is closed, I would expect current to jump up around the specified 1.1 A. That's from the 80 supply, the current from the 1st supply should jump up too but not the same amps as the 80 V load.

[John Futter]

rhorst
please follow the board rules re name convention and posting rules

[Arun Luthra]

Thank you for your patience everyone. It turns out it was a bad CABLE. (female to female DB-9 cable connecting the EXDC80 drive module and breakout/pinout board).

It spins up beautifully now.