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Display is Not Dead!

A project log for Bench Power Supply

Designing an open source, modular bench power supply to rule them all.

the-big-oneThe Big One 05/26/2015 at 14:486 Comments

I was worried that the 10V magic smoke adventure from the weekend had killed my display... a quick test showed that it worked, but I didn't do much more than 5 seconds to see if it showed something.

Last night, after re-soldering the entire controller board for a third time, (this time verifying the operation of the linear regulators before soldering them on), I was able to verify that the display works. There are still some problems somewhere; I suspect the issue is the DACs (which, given that they are MSSOP-10, I have been unable to verify without soldering onto the board), but I uploaded a simple display test program (seen below) and you can see that all characters are showing properly with no errors or artifacts.

Tonight I hope to have time to verify (and replace if needed) the DACs, and (finally) get the controller working.

One more note on the ISP issues: on this go-round, I decided to not populate the pullups / caps / TVS diodes on the encoders (which are shared with ISP pins). Those are the root cause of the ISP problems, and instead of putting them on the board I can solder them directly to the encoders. It is a bit more annoying, but perfectly doable, and will allow me to re-flash using the ISP if needed in the future.

Cheers

Discussions

zakqwy wrote 05/26/2015 at 15:25 point

Looks great! One thought--diffused LEDs? I've found clear T 1-3/4 units aren't super visible from off angles..

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The Big One wrote 05/26/2015 at 15:27 point

Yeah I don't know if I will keep these or not, but they are what I have on hand for now.  Time will tell.  An easy fix if it turns out to be needed is to cut the dome off them and file it flat (but rough) as a diffuser.

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zakqwy wrote 05/26/2015 at 15:32 point

For sure. I'll bet you could also just sand 'em down a bit with some fine sandpaper. The brushed aluminum is awesome.

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The Big One wrote 05/26/2015 at 15:42 point

Thanks!  I am very happy with how it turned out :-)

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The Big One wrote 05/29/2015 at 03:00 point

FYI, you were 100% correct on the original 'water clear' LEDs not looking good, and were also 100% correct on the sanding suggestion.  Thanks!

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zakqwy wrote 05/29/2015 at 15:07 point

Awesome! Keep up the good work. This is on my list of stuff to build!

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