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Displays not initializing after working for a while


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My displays were loading up fine the past few weeks when I just had them plugged into the core with the MIDI I/O mods attached.

Today I finished up the wilba CS and plugged it into the Core, restarted the Core with the MBSEQ_HW.V4 file in the SD card and now I just get those bars/squares on the LCD when I plug it in. Even when the CS is removed and I go back to barebones Core and one LCD, there is nothing but the black squares.

Been troubleshooting for hours. Didn't change anything on the core. i even made a new ribbon cable thinking that something was wrong there. MIOS Studio seems fine (see attached).

Any suggestions? Thanks.

Screen Shot 2017-10-18 at 9.50.14 PM.png

Edited by EvilEvilEvil
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I have taken the values from an NG flashed core that has a working LCD on J15A. Measurements taken starting at  top pins (#1), key on left side    

Did you adjust the contrast pot?

Better than Multimeter and Oscilloscope is the Logic Analyser. It can be very cheap too, 9€ here! 24MHz is enough. You will see multiple waveform as concrete things on a timeline, very good to lear

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Yes, I tweaked both the brightness and contrast. 

I tried another display and a new ribbon cable - still nothing.

I checked all my solder points to see if anything came loose, checked for debris that might cause a short.

At a loss here as it was loading up to the default screen for weeks until I hooked up the CS.

Before, I never had the SD card inserted and this time I inserted it with the MBSEQ_HW.V4 file in the root directory. But even when I take the SD card out now the display still shows squares. Could something have been affected by the SD card?

Edited by EvilEvilEvil
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You don't need an SD card to display LCD messages. 

Photos of the PCB please. 
What LCD are you using?
Is the voltage jumper correct?
Does one LCD work by itself?

Is the shift register 74HC595 (not HCT)? Can you swap it for another to test?

Edited by latigid on
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Here are the pics. I do not have another shift register to test with atm.

https://www.dropbox.com/s/0sjsstrz42t68ja/1.jpg?dl=0

https://www.dropbox.com/s/vjkdq31xcx9wtkx/2.jpg?dl=0

https://www.dropbox.com/s/9k8o3szcungkhxx/3.jpg?dl=0

https://www.dropbox.com/s/1vaz7nhafxn1m5y/IMG-3078.JPG?dl=0

https://www.dropbox.com/s/tjbm15s41sy59cf/IMG-3079.JPG?dl=0

https://www.dropbox.com/s/vcn79o98kpq3zr2/IMG-3080.JPG?dl=0

let me consolidate all the info

• The Core and LCD worked fine for several weeks while I awaited parts to build the MIDI I/O and CS

• I built the MIDI I/O and tested it with MIOS Studio - no problems

• After building the CS I plugged it in and transferred the MBSEQ_HW.V4 file to an SD card

• turned it on and only have squares on LCD,  MIOS studio reports that Seq V4 is installed

• Unplugged the CS - still squares

• Removed the SD card - still squares

• Tried another LCD - still squares

• Tried another ribbon cable - still squares.

• Tried other 5v power supplies - still squares

• Adjusted brightness/contrast - still squares

• Wife is getting upset - still squares

• Have to pick the kids up - still squares

• Going to sleep last night - still squares....

Edited by EvilEvilEvil
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The LCDs expect an "enabled" signal, so I wonder if it's a problem having only one connected.

Load up something easy such as MB_NG and see if it works.
Reflow the joints on the 595 socket (chip out first). You could have some cold joints; ideally they should not "bulge" around the PTH pad. 
What is the scratch between J15A/B headers on the solder side?

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Maybe a voltage problem? I see in your pictures that you use the Mini-USB- port.

The 5V of the Mini-USB port goes through a BAT60J diode to the board. It has a voltage drop of 0.28V... 0.58V depending on the current flowing through it.

Do you have the same problem when using the Micro-USB port or an external power supply?

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On 10/19/2017 at 4:39 PM, latigid on said:

The LCDs expect an "enabled" signal, so I wonder if it's a problem having only one connected.

Load up something easy such as MB_NG and see if it works.
Reflow the joints on the 595 socket (chip out first). You could have some cold joints; ideally they should not "bulge" around the PTH pad. 
What is the scratch between J15A/B headers on the solder side?

• Previously it worked fine before with just 1 LCD 

• Loaded up MB_NG and get an error "no response from CLCD". See attached - perhaps this is a step in the right direction.

For the ribbon cables I followed the wiring 1->15 2->16 and so on... Again, it worked fine up until now so not sure what could have happened.

• Reflowed the joints

• The scratch was just a smudge - I rubbed it away.

• I tried many 5v options and both usb ports 

 

Thanks all for the help so far! Much appreciated...

EDIT: The resistor array is 1k Ohm - I know others had this problem because they accidentally used 10k.

EDIT 2: I downloaded the MIDI 2x2 program and the MIDI i/o modules work fine with it. Not sure what this proves but perhaps we can cross out the possibility of some faulty components?

 

 

Edited by EvilEvilEvil
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4 hours ago, TK. said:

To the "testlcdpin d1 0" check: do you see the same effect if no LCD is connected?

Best Regards, Thorsten.

Hey TK - thanks for joining in!

Yes, I am only running the pin tester with the display disconnected. Now that I hooked up the LCD, the error is gone!

But still nothing from the display :(

Edited by EvilEvilEvil
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This isn't plausible, it really looks like a strange hardware fault which is impossible to debug remotely for me. :-/

Did you ever connect the LCD the wrong way?

From software point of view, the LCD configuration can't be changed directly, especially not from the MBSEQ_HW.V4 file.
There is only one way to select a different LCD type (which could result in such a effect), and this is via the bootloader update application.

So, if you want to doublecheck the unlikely event that for some unknown reasons the LCD configuration has been changed, you could upload the bootloader update app, enter "help" and check the selected LCD type which is printed by "help". It should be 0x00

This app has the same "testlcdpin" command, so it also provides a nice way to doublecheck the hardware with an alternative firmware build.

Best Regards, Thorsten.

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Thanks. This is what I get on the bootloader screen 'help'. Perhaps I did connect the lcd wrongly at some point. Would this really have the potential to damage it?

 

EDIT : Just noticed that IC1 is getting pretty hot when it's plugged in for 5 minutes or so. I think I'm just going to cough up the $70 and build a new board... 

EDIT 2  :fear: Amateur hour. So when I reset IC1 late last night in all my frustration, I put it in backwards.... :blush: hence the heat. HOWEVER - when it was reversed, the bootloader recognized LCD 1 and the testlcd pin D1 worked (screenshot 1). Now that IC1 is back facing the correct direction, bootloader says "failed: no response from LCD 1" and testlcdpin 1 doesn't work again. Does this shed any light on the situation? That it recognized the LCD when IP1 is (accidentally) reversed? See screenshot 2.

 

 

Screen Shot 2017-10-23 at 7.28.21 PM.png

Screen Shot 2017-10-23 at 8.52.14 PM.png

Edited by EvilEvilEvil
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Humph.... Sigh

 

Just built an entirely new Core board. Same result (sad face). Still getting the same results from the testlcdpin. So that makes me think neither the Core or the LCDs are to blame.

What would you do now? New Discovery Board?

Edited by EvilEvilEvil
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It's easy to fry LCDs, e.g. if you get the backlight circuit going full blast onto the logic pins, reverse the power connector or a data input etc. I'd try another LCD. Ensure the cables are connected; it can be confusing without polarised headers (always missing from LCDs). Don't trust the notch on the Core board, use the stripe of the cable to align the power or backlight. 

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A common problem with Eurorack power headers is they only work if the notches are polarised the same way on both the bussboard and the module. If the module has "pin 1" on the opposite side as the power output header and both headers are keyed, there is no way to correctly plug in the cable.

The Core schematic is correctly drawn as a "mirrored" header.

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On 10/31/2017 at 4:33 AM, latigid on said:

A common problem with Eurorack power headers is they only work if the notches are polarised the same way on both the bussboard and the module. If the module has "pin 1" on the opposite side as the power output header and both headers are keyed, there is no way to correctly plug in the cable.

The Core schematic is correctly drawn as a "mirrored" header.

Still not quite sure I understand. I have the red stripe going from the inner pin closest to the brightness/contrast pots to pin 15 on the LCD. The LCD has numbered pins.  

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