Computer Power supply strange 5V and strange behaviour Teensy is connected

[kurt-olsson]

Question nr 1:
Does anyone of you using Teensy + Teenysuino + X-plane notice a keyboard lag/disable.

As soon as i fire up X-Plane my keyboard starts lagging, cant copy etc.
Super annoying while mapping datarefs and inputs to my controller.

i will try a keyboard with cable if this still occures, but i had no problem with this before...

Question nr 2:

I have a Computer PSU (is says 20Amps on 5V) that i use for my 12v and 5v.
When my second panel is completed i added this one aswell to my 5V for backlight on both panels.
But the wierd thing is that i can only light one at a time. Both work, but only one each time.

I think this has something to with max output on the PSU / red(5V) cable? Or do i have to solder together all the PSU ground cables?

Anyone had this problem?

No problem with my Korrys 24V on both panels.

[kurt-olsson]

This is wierd!

The PSU is rated at 20A on the +5V but it can only supply backlight to one panel.

Am i missing something with my circuits?

I plan to join all the cables / volts to see if that is the limitation.

This is how i connect it today.

[kurt-olsson]

Hm. Lots of PSU convertions put a 10W 5 Ohm resistor on the GND and +5V. Looks like there need to be a little bit of resistance to get full output?

[kurt-olsson]

...and this story comes to an end.

If you make your PCB like crap, loose not perfect fit etc you will end up with trouble.
I noticed that my backlight went black once i fastened my panel to the overheadframe.
I cant explain the answer to this but there must be some sort of contact where there should not be. After trying to see what was the problem the Teensy got fried (third this week) and i threw the PCB and teensy in the garbare.

I have to redo the complete PCB for the panel again. =(

[Trevor Hale]

Peter that sucks!  Think most of us have been there though.  Keep pressing on my friend, don't get discouraged and make it happening.
Keep us posted.
Trev

[kurt-olsson]

Thanks Trevor!
That PCB was doomed from the beginning. I just wish i understood what happened so i can avoid it in the future. 😊

[Joe Lavery]

Peter why don't you post your PCB design here and see if one of the many experts can see what the problem might be.
Just a thought but as Trevor said don't lose heart.
Joe

[kurt-olsson]

Thanks Joe,
if i get into trouble again i will make a complete Schedule for my PCB and how i am connecting it with my PSU.
I know its alot to ask for help without a scheme, that makes it pretty impossible to help. =)

Will make another one first since my belives is that i think that the poweroutput was in contact with the panel/overhead frame etc.
The circuit was bad becuase it fried my Teensy, so somewhere there must have been a shortage. =(

[mickc]

Not sure what breadboard you are using, but just be careful that your mounting screws aren't going through a track that is connected elsewhere on the board, and shorting to the case - or to other tracks through the case.

Also remember that the case will be grounded through the backlight connector

[Joe Lavery]

I can sympathise with you there Peter, I've made many PCBs over the years, even had some produced in China. But I've also made some duds in the process. 
Mine were mostly for simple circuits or for backlighting, so fairly easy to diagnose any issues.

Joe.

[kurt-olsson]

I think Mick has the answer.
This is what i tried:

1 Taking down the panel and put it on my chair everything worked, backlight on all panels.
2, lifting the panel by hand and mounting it in the overheadframe, as soon as the panel touched the Dsuz rails my backlight went out. I think there was a 5v shortage somewhere so that the amps went into the panel instead of the lamps... (or something =))

And in the end i think this is what fried my Teensy, passing 5V in it.

My PCB is selfmade. It is hard to make sure that the screws and the PCB is totally separated from the panel and its casing. I need plastic spaces or acrylic plate to protect it.

Hard stuff...

[Trevor Hale]

Margerine container lids work well to make plastic washers..  Drill a hole in them and cut around the hole.
Nice and easy and provide a nice easy way to isolate.  Unless your dzus screws that go through the PCB are actually contacting copper inside the mounting holes, you may want to drill them out a little bigger also.
Trev

[Joe Lavery]

You can buy really cheap plastic washers from eBay, in all sorts of sizes.

As far as isolation goes, I tend to use a countersink bit to go around all the holes to remove any copper. In fact if I'm creating my own backlight circuits I cut an isolation track right around all the holes.

[kurt-olsson]

Thanks for all inputs! I ended up buying washers from ebay, dirt cheap!

[KyleH]

.....

My PCB is selfmade. It is hard to make sure that the screws and the PCB is totally separated from the panel and its casing. I need plastic spaces or acrylic plate to protect it.

Hard stuff...

Pro tip- When designing the PCB thinking about the mechanical is just as important as the electrical. I don't know what PCB software you are using, but I make the mounting screws a component for the PCB with a predefined hole size and electrical clearance rule and keepout area a distance around the screw head. That way when I'm running the traces I know exactly how close I can safely come to the screw hole.

I also do the same with any other mounting surfaces that may be in contact with the PCB. In the attached pic, I have the mounting L-bracket drawn on the PCB to help keep traces and ground planes away.

[kurt-olsson]

I should have added, i make my custom pcb. But the isolation parts still adds for it.

[KyleH]

Ah...ok your using Veroboard, not a PCB.

[kurt-olsson]

SAME PROBLEM AGAIN!

I have posted a scheme how i set my electrics up.
If i light each panel at a time it works, but i cant get them all to work.

I had a wierd thing also.
Connecting only one panel that i havent even interfaced, it lightened up my other panel a tiny bit without even being connected!

I am missing something really fundamental here about electronics... =(

[kurt-olsson]

Oh  to  mention, these two 5v are connected through a ULN2803A.

Maybe there is something wrong there. How come each of my interfaced panel worked with the "uninterfaced" panel but not with eachother?

[KyleH]

Ok lets go back and simplify it. Disconnect your 24V supply including its ground, and your USB to the PC. Just have the 5V and only the 5V connected, with the panels in the overhead.

If they work then. Connect either the 24V up again and check. If that works, then disconnect the 24V supply and connect your USB cables to the PC and try again. Try to isolated it down to the one connection.

What are the part numbers of the 5V and 24V power supplies you are using?

[KyleH]

Oh  to  mention, these two 5v are connected through a ULN2803A.

Maybe there is something wrong there. How come each of my interfaced panel worked with the "uninterfaced" panel but not with eachother?

Ok, going to need a more detailed schematic of how you've hooked this up.

[kurt-olsson]

Kyle, thank you very much for helping me. Its very late now and i have to get some sleep (after this painful experience again hehe)
But i will give you the details of how i am connecting my teensy board, but you have allready made a good suggestion.

I will try your suggestion and come up with more detailed scheme of my teensy board.

thanks

[kurt-olsson]

I use a 400W PSU. Model: PS-400, 44139 (i use this for 5V,12V)
and  a 24V power supply, max 3Amps. Model PS2403.

[kurt-olsson]

I just came up thinking with one thing...

What if i put 5v+ on the top screw for the backlight on panel 1 and 5v+ on the bottom screw for the backlight on panel2. Then the current will flow in opposit directions?

[KyleH]

I'd have to see a picture for reference.