LCD display not working...

4teenth wrote:Just tested for continuity at all the pins (Well, the ones that are connected, as far as I can see on the board layout), and all good apart from I'm not getting continuity from pin 2 to TM3. I am however getting 4.1V there - is that enough out should it be 5v? If I use a wire to connect pin 2 to TM3 I just get a brighter display of what I currently have now...

it should be closer to 5V according to the spec of the newhaven display it should be between 4,7V and 5,5V.

on my nava i measure 4,81V

So, now I have reflowed some joints on the Atmega and replaced the EPROM chip and I was now able to init the EPROM on startup.

I now have the correct lights flashing on startup and I'm able to play patterns and programme them fine, but still the display is as before: top row solid blocks and nothing on the second line.

I have checked the connections between the display and the Atmega and all are good.

TP1 voltage is also 0.

I'm at a loss as to what to check next.

Quick update - display still not working but booting into TM2 adjustment process (holding down Enter) allowed me to set TP1 to 5v successfully.

Still no idea about the display

Success!

The issue was a broken connection between pin 14 on the display and pin 29 on the Atmega. I had tested these all before as per the diagram that KlangGenerator uploaded on here:

And they all looked good. I did this several times!

What I had failed to do was to check both sides. I.e. check pins top side from LCD to Atmega and the same bottom side as well.

My fix was this (I will tidy it up once I have tested everything else):

What confused me is that if I test between these two pins from the bottom i.e. LCD pin 14 to the bottom of the IC socket pin 29 I get continuity!!!

Anyway, I had flashed the latest firmware this morning so this is what I have now:

So if anyone else is having that issue where things seem to be working except the display and you're getting one row of solid blocks on the top then check the connections from LCD to Atmega, from both sides

Time to make some music!

Thanks for your support. This is a very cool project and a great site.

Hmmm... So I checked again, and I'm getting continuity from the ATMEGA to the display, both if I test from the bottom (Components side) and also from the top - even testing from the non-soldered row of solder points at the bottom of the display, which should be twinned with the top row that have been soldered in. All good it seems...

So what is your current status? Do you have all bottom row sequencer lights on steady? I did and so I replaced IC115 (the EPROM) as per KlangGenerator's advice and then - after reflowing a couple of joints on the Atmega - I was able to run the init EPROM sequence and things started working better.

No, my Nava is working completely fine apart from the screen, basically...

I don't know what to suggest then

Maybe someone else will have some suggestions.

angusmack wrote:I don't know what to suggest then Maybe someone else will have some suggestions.

Me too!

I guess the 1st thing to investigate is the lack of continuity from pin 2 to tm3, and go from there...

Hopped back onto this after a bit of a break doing other things - so I found the pin of TM3 that connects to pin 2 of the display was connected as it should be to the button next to it, but pin 2 wasn't connected. So I reflowed, and still no joy. So I did a bit of a hack and connected pin 2 to the pad of switch 18, and hey presto, my display is now working!