Design of Parallel Video Board 'Backplane'

[ElEctric_EyE]

ElEctric_EyE wrote:

... Will do another PVB board next week...

Slightly off the schedule
I have now assembled another PVB meant to be a 'pass-thru' video device meaning it has: video RAM, Spartan 6 FPGA, 2 FPGA PROMs, and FPGA PROM MUX. There is no videoDAC or RGB connector since it is passing 16-bit RGB, HSYNC, VSYNC and pixel clock video signals to the next board.

I've been witnessing a problem the past few days: The 2 boards only work when the pass-thru board is in slot K3 and the output board is in slot K5. I will have to troubleshoot this backplane immediately.

EDIT: I see a design error. The original can oscillator spec's output @8mA. Too little to drive 6 PVBs, or even 2. The fix is an easy one.
EDIT: The problem was not in the backplane, but incorrect soldering of PVB2. Working now.

[Arlet]

ElEctric_EyE wrote:

I'm done soldering today. 800+ holes.

If there's enough room between the rows of pins, connectors can be soldered very quickly. Crank the iron up full whack, run it along one side of the pins, and run the solder wire on the other side. With a bit of practice it's possible to do a couple of pins/second.

[GARTHWILSON]

Arlet wrote:

Crank the iron up full whack, run it along one side of the pins, and run the solder wire on the other side. With a bit of practice it's possible to do a couple of pins/second.

Yep. Temperature-controlled ones often can't do it. It was a surprise to our production people when I showed that soldering a plastic switch years ago resulted in less melting and damage if they would use a hotter soldering iron so as to be able to complete the job so quickly there wasn't time for the heat to reach the plastic before everything was cooling again.

[BigEd]

Interesting!

[ElEctric_EyE]

Thanks gentlemen!
But I've finished this backplane months ago and it's a solid performer.
Just FYI, I haven't noticed any noise issues with 16-bit RGB data flowing at 70MHz through 4 boards. 2 of them don't even have a single bypass capacitor yet!

[Arlet]

ElEctric_EyE wrote:

2 of them don't even have a single bypass capacitor yet!

tsk tsk

[BigDumbDinosaur]

GARTHWILSON wrote:

Arlet wrote:

Crank the iron up full whack, run it along one side of the pins, and run the solder wire on the other side. With a bit of practice it's possible to do a couple of pins/second.

Yep. Temperature-controlled ones often can't do it. It was a surprise to our production people when I showed that soldering a plastic switch years ago resulted in less melting and damage if they would use a hotter soldering iron so as to be able to complete the job so quickly there wasn't time for the heat to reach the plastic before everything was cooling again.

Understanding thermodynamics helps. It's the same principle that allows someone to walk on red hot coals and not get burned.