|
|
Post by GA-Dawg on Feb 29, 2016 14:29:51 GMT
Thanks Paul.....I still painting...Just got back from a work trip and haven't worked on my setup in a week or so but this will come in handy.
|
|
|
|
Post by paulg100 on Feb 29, 2016 14:53:20 GMT
No probs,  this is how NOT to do it, ha  the amount of cables creeps up on you. BTW this is not the environment ive been testing the noise suppression in, i have the amc and sensor cables etc well away from this mess for that! some ferrite beads turned up today that i been waiting on, so will be testing them tonight on sensor cables and/or maybe 10v outs. |
|
|
|
Post by mhensen on Feb 29, 2016 20:19:17 GMT
Hi Paul, Ferrits .. that's a good one.. I could get to the right word!! That's what I used in my OSW steering wheel.. seemed to help a lot, curious about your findings with these!!! You asked for my cabinet pictures.. wel almost forgot .. but here the are, although a bit better now as I am finishing up, but anyway  the front.. The safety switches wires aren't really nice :-( too much in a hurry I guess!  and the back side.. BTW the foil on the left is the connector cable to the extension board... Wrapped it in foil as a desperate attempt to shield it somewhat! |
|
|
|
Post by paulg100 on Feb 29, 2016 21:27:10 GMT
OK thanks Michael, the cab looks great with that carbon wrap, really clean.
I had a quick play around with the ferrite bead i ordered, put across the 10v lines it does reduce the noise further still but not by a whole load.
Dont want to speak to early but with the caps and settings a013 to 3% and b082 to 1.00 the crackling has completely gone!
at the moment the amc and cables from one vfd are outside the cabinet with the rest of the motors and vfd's switched off so might be different
once its all hooked up again but looks promising.
Am held up now waiting for new foil wrapped cable (100% coverage) for amc control and a die-cast aluminium box to house the AMC in.
Really underestimated the EMI problems and how important it is to keep a noise free loop as much as possible, but getting there.
i noticed in your pic of cab at the back you have the AMC control leads crossing over the powerlines? that might be a problem.
Its odd that other builds have been less meticulous with their cabling but things still appear to work OK.
|
|
|
|
Post by paulg100 on Mar 20, 2016 17:47:01 GMT
OK a small update, work has been really busy so not much time to work on sim at the minute. Still!! busy rewiring sim after using wrong cables and having noise issues in loop. Has taken allot of time to get more cables and parts for EMI enclosure which has turned into a mini project of its own. Trying to route cables for best practice takes allot longer than just bunching everything together!! With the cost of the box and then the EMI glands the enclosure ended up costing as much as the main cabinet but really pleased at how its starting to come together.   |
|
|
|
Post by paulg100 on Mar 20, 2016 17:51:12 GMT
For the top platform I was hoping to use my old rig to save allot of work. After I tried mounting it I wasn't happy with how front heavy it was as there is allot of unnecessary metal in this particular rig. Plus the colour scheme was not going to match.  so nothing for it, to get the best result I'm going to build something myself, probably using plywood to keep weight down. Have ordered a new chair which looks much better. Once the wiring is done ill start on designing and fabricating a frame for the wheel, peddles and gearstick. Not in any major rush with this, just want to do the best job I can, so may take a bit.  |
|
|
|
Post by mhensen on Mar 21, 2016 7:34:25 GMT
Hi Paul,
That looks nice and clean!!
I would really consider to topbrace the motors. I think I have found the reason of why I have the tremble in my front end..
Nothing to do with noise but I think I have made the lower frame too weak, this causes the motors to vibrate back and forth in the frame and because of the top weight this increases to rocking back and forth..
So I have to redo my lower frame.. but for now I work a bit around it as I have no time, busy working :-(
|
|
|
|
Post by paulg100 on Mar 21, 2016 10:54:36 GMT
Hi Michael Thanks for the tip, yes i have plans for making additional bracing frame, it will be welded steel. Maybe its because my gearboxes and motors are bigger (weigh more) but i didnt have a noticeable problem like yours when i had it moving before. This was only with me sitting on the main upper frame with nothing else on top. Once that extra weight is added maybe the problems will start without extra bracing. Glad your getting to the bottom of your issue and hope you find some time to fix it soon. Im in the same boat at the moment, to busy at work.. but it is good in the end as its paying for this project!! |
|
|
|
Post by GA-Dawg on Mar 21, 2016 19:49:45 GMT
Hi Paul,
What did you need up using for your power lines
-GA Dawg
|
|
|
|
Post by paulg100 on Mar 22, 2016 6:52:42 GMT
Hi GA
Its 1.5mm 4 core CY Cable. (not SY!! or YY.)
You could probably use 1mm if just looking at amps but the thicker the cable the less inductance.
Then I twisted the pairs together using the drill trick (2 motors in each bundle) to help reduce common mode interference. pots are twisted pairs also.
Ive Tried to keep incoming, outgoing and control cables separate from each other, and where I have to cross make sure its at 90 degrees.
EDIT: Also the braid for incoming power to VFD and outgoing to 3phase to motor is terminated at both ends.
Control cables only terminated at the AMC end. Ive used the braid on the pot wire as ground which may not be strictly ideal (can cause ground loop?)
Might be better with 3 cores and seperate sheild for pots. I tried a USB cable as an alternative and tested using Oscope and 1 vfd/motor, the USB cable didnt make any difference to noise level so hopefully the current
cable i used (2 core copper shielded speaker wire) will be OK.
Seems to be allot of conflicting theories on ground loops but terminating the braid of the outgoing VFD power cable at both ends seems to be consistent no matter what you read so id definitely do that.
thanks.
|
|
|
|
Post by paulg100 on Mar 31, 2016 20:38:14 GMT
OK been scratching me head for the past week or so, wiring is all finished again but couldn't get any movement. Then I notice a burning smell and that the light on the 24v PSU was flashing once it was connected to the 6dof extension board and outputting random voltage once connected. I guessed the 24psu had burned out for some reason so I ordered a new 24v 1 amp PSU to test. Just tried it with the 6dof board isolated and nothing connected other than the 24v psu.. and could smell burning again! Traced it back to the UDN2981 chip here which was also really hot:  I cant see any damage on the underside of the board but im guessing the chip has gone bad/damaged (it looks it from the top) Im sure as can be that i havnt reversed the polarity of the 24v inputs at any time. I already ordered some spare chips from ebay/china but they wont be here for some time. I think ive found the same chips from a UK supplier and have ordered one which should be here next week. Im worried if i just slap a new chip in that the underlying issue may still be present and will cause damage to the board? (if it hasnt already!!) tronicgr Thanos is there anything specific that could cause this or any advice you can give thanks? |
|
|
|
Post by tronicgr on Apr 1, 2016 15:48:31 GMT
These transistor chips are very sensitive to static electricity, you might have zapped it by touching the board. I test each one before I ship the boards. I often get bad ones not working outputs or even shorted like yours.
Its good to always have same of these spare. That's the reason I prefer to use IC sockets to be easily replaceable.
Thanks
Thanos
|
|
|
|
Post by paulg100 on Apr 1, 2016 16:19:02 GMT
OK thanks Thanos i had a feeling that could be the issue, ive done my best to avoid touching the chips.
I ordered an anti static wrist band already (been meaning to get one for years!) so hopefully that will help avoid this issue again.
|
|
|
|
Post by paulg100 on Apr 4, 2016 11:56:42 GMT
tronicgr Hi Thanos I received a replacement IC for the UDN2981A today The chip i have is infact UDN2981AT 1009 D009564 Just wanted to check this is actually the same chip before i plug it in? All the UDN2981's sold on ebay etc seem to be sold as the same chip but with slight difference in the code's. Seems to be essentially the same chip www.farnell.com/datasheets/58047.pdfBut best i check with you just in case, thanks
|
|
|
|
Post by tronicgr on Apr 5, 2016 10:07:30 GMT
Its the same.
Thanks
Thanos
|
|
the amount of cables creeps up on you.
