TMDSHVMTRPFCKIT USB problem driver problem

are you using TMDSCNCD28035 and the USB connection on the HVMTR Kit?

Please verify all jumper settings for using AC supply.

Also, if you have a DC supply it is always recommended to provide high voltage DC directly during development. It will help with noise.

Hi Chris,

Thanks a lot for your fast response. 

Yes. I am using using TMDSCNCD28035 and the USB connection on the HVMTR Kit.

And all the jumper settings are verified step by step according to the Quick Start Guide.

We actually don't have a HV DC supply at hand. If this is indeed a defect in the hardware for this one, I wonder if it is possible we can get a RMA and get a replace new one? 

Thanks,

Jian

I don't think the board is damaged..I would suspect simple noise is making the connection disconnect.  I use this kit often enough with the AC input...only difference is I only use the controlCARDs with their own isolation/emulation built-in now.  But when I did use the on-kit isolation/emulation I never saw this problem.

i've sent this off to some others to see if they have thoughts.

I have never had this issue either.

I suspect some grounding problem. If you have an isolation transformer, use it to power your computer. This may fix. However, you may also want to try one other thing on the board. Within the emulator block (macro), there is a decoupling cap C17. Remove it and test it with low voltage. If the problem doesn't show up again, then replace C17. If not, we cant imagine much right now. Let us know how it goes.

rgds,

ramesh

Hi Ramesh,

Thanks a lot for the advice. After two days of oscilloscoping and debugging, it turn out our big thick ion table is the major culprit. Large voltage (over 10V) can be induced on the table, which somehow screw up the usb connection, even though the usb is supposed to be isolated(this part I still have difficulty grasping).While everything is on the table, we tried:

(1) ground both motor and  the table, nothing improved; 

(2)ground the table, floating the motor(with a rubber mat in between the table), in this case, the 60Hz induced signal on the table is gone, but still some high frequency induced large voltage persists, thing improve a little bit, the connection can be maintained for a while;

(3) ground nothing but floating the motor from the table with a rubber mat, in this case the connection improved, but after while(15 min), the disconnection happens;

(4) Finally, once we move everything off that table, it can be successfully maintain USB connection, only disconnection only happen once or twice so far. We are trying to move everything to a wood table, I'll keep you posted on what will happen.

So what is the besting grounding scheme for this setup in your mind?

Thanks a lot.

Regards,

Jian

For USB disconnection, we route the USB cable through ferrite cores to block HF common mode pick up. Or, use an USB cable with local ferrite filters, or worst case, physically place the computer and USB can away from the HV wires to the extent possible.

rgds,

ramesh

forgot to mention, we actually have both a ferrite core on the usb cord and at PC end, we added a usb isolator.

Do the motor need to be grounded? What is the best grounding scheme for this setup?

Yes, grounding the motor helps as well. When you use metal table, it can act as a large capacitive plane and may lead to some nuisance if proper grounding is not done. We use wooden work bench and generally don't run into show stoppers that easily.

rgds,

ramesh