3.1 Synthex board problem (1 row of solid white boxes)

[zoggynog]

Hey All,

So I (a complete novice) ordered the 3.1 kit from Synthex. I assembled the kit, took my time, and had a couple of vastly more knowledgeable buddies watch over the process (help make sure I didn't mess this up.)

I now have the following happening when I provide power to the Megadrum:



I have connected Pin 1 (ground) and Pin 3 in an attempt to test contrast. The LCD does not change. I have also tried with the keyboard input to change the contrast blindly by following one of the troublehshooting steps provided from the forum.

I have also used an ohm meter to check for connectivity all the way from the pin header on the LCD to the IC itself. Everything tests good.

Additionally the device does register in Windows ( I hear the sound and see the device in device manager).

If anyone else has had prior experience with this symptom, could you shed a little insight?

Thank you very much in advance for you assistance!

[dmitri]

If you read viewtopic.php?f=3&t=492 , and I guess you did, than you should have have read this:

If you adjust the contrast from the firmware (blindly, since the data communication between Atmega and the LCD is presumably broken, by pressing LEFT for a few seconds to guarantee you're in the first point of the menu and then pressing UP/DOWN) but still not able to see black boxes, than either the LCD is faulty or Atmega is not working properly. In that case temporarily connect pin 3 of the LCD to pin 1 ground. DON'T ACCIDENTALLY CONNECT pins 1 and 2 of the LCD - you may damage USB port or power supply. When you connect pin 3 of the LCD to the ground you set LCD contrast to the maximum and black boxes in the top raw should stand out straight away. If they don't, your LCD is faulty. If they do, your Atmega is not working properly.

From which you can conclude that, provided your wiring is good, your LCD is faulty.

[zoggynog]

Sorry Dimitri,

Kind of stupid to be asking for reassurance for a question you already answered.

I guess with this being my first time to do this sort of thing, it was hard to accept I was just dealing with a faulty lcd (and not some self inflicted screw up).

After I wrote my original post, I installed MCT and wired up a Guitar Hero World Tour Cymbal for testing. I'm seeing Signals!

Sorry to have doubted! I've ordered another LCD via Ebay.

I can't wait to get it all wired up and start playing with this thing.

Thanks for putting up with this (and future) noob questions.

[zoggynog]

Well, I ordered a new LCD display to fix my faulty one. I soldered it up, and it now has the exact same problem my previous one had (one row of solid white characters...see above picture). I'm starting to think this is not LCD related.

Is there any chance this could be related to a bad IC?

The funny thing is, the Megadrum works! I hooked it up to a Gutiar Hero World Tour Cymbal pad. Have the pad midi mapped and working fine under BFD2. The Megadrum is doing what it is supposed to do, I just can't get a display out...

Any advice?

[dmitri]

I have connected Pin 1 (ground) and Pin 3 in an attempt to test contrast.

Are you sure the contrast doesn't change even a slightest bit?

[zoggynog]

When I connect Pins 1 and 3 with this LCD, I can see the contrast change on the top row (it gets brighter). Only the top row shows.

Starting to sound like a bad IC?

Thanks for the help by the way, there's not many projects where the lead designer is also the tech support. I appreciate it.

[dmitri]

When I connect Pins 1 and 3 with this LCD, I can see the contrast change on the top row (it gets brighter). Only the top row shows.

If you had noticed it before, I wouldn't suggest your LCD was faulty.

Starting to sound like a bad IC?

I very much doubt it since you're saying:

The funny thing is, the Megadrum works! I hooked it up to a Gutiar Hero World Tour Cymbal pad. Have the pad midi mapped and working fine under BFD2. The Megadrum is doing what it is supposed to do, I just can't get a display out...

I'm 99% sure your problem is with connectivity between Atmega and the LCD.

[zoggynog]

Let me clarify what's happened so far.

The first LCD (Blue/White) I received with my Synthex kit showed only the top row (raw). When I touched Pins 1 and 3 I could not see a contrast change in the LCD.

Perhaps it was changing very slightly and I was just unable to see the contrast change. I ordered a new LCD.

My second LCD arrived today, I connected it, turned on the Megadrum, and had the same initial symptom my previous LCD had. Only the top row lights up, no visual data.

Since I started posting today, I have determined a few things about my new LCD:

1. I can adjust the contrast of the top row connecting pins 1 and 3.

2. I can use the keyboard inputs to blindly adjust the contrast by pressing up and down after pressing left for a few seconds. (Just verified this after my last post).

3. Only the top row can be adjusted, the bottom row does not appear to be on.

4. I see no <Megadrum> logo at boot up.

5. As usual, the Megadrum is still working fine otherwise, talks over MDT, even lets me map in BFD2.

Thoughts?

I'm so close, I can feel it!

[davem]

Did you check joints connecting the Atmega to the LCD? Make sure there's no bits of solder across joints etc?

[zoggynog]

Hey Dave,

When I booted my Megadrum with my first LCD and had the initial problems I checked all my connections for proper voltages between the Atmega and the LCD. All were correct.

I've been doing this build with the help of my boss (without him around I probably would not have been so brave as to try to do all of this). I had him examine all my joints. I also had a co-worker take a look.

Both of them have several years of experince with this sort of thing (I do not). So I guess to some degree Im taking their word for it, but I think my connections are clean.

At one point, my boss had me go back over some joints using a magnifying glass we have at work. I found some pads that needed additional solder. Fixing them did not change anything, but hopefully will prevent bad connections in the future.

I'm also using older lead based solder, which I'm told is the "good stuff" for connections "not so good" for health perhaps .

I will be retesting the voltages on my new LCD again tommorrow.