Infinite false notes... Any help???

[timekeeper]

Hello. Up to now, I was testing my MegaDrum, so I had only one multiplexer (4851) on my board. I had false hihat notes for every input I tested, but since I hadn't finished the jack board and I was simply hooking a wired piezo to an ide cable going to the board, I thought I would be able to eliminate it by setting Xtalk. But today I plugged all four 4851s and suddenly, the midi log in MDManager goes wild and toontrack solo makes hihat ringing like I was Deen Castronovo on Marty Friedman's "Dragon Kiss"!!!
Here's a pic:
http://imageshack.us/photo/my-images/83 ... d01uy.png/

I am using Synthex's v2.5 pcb and v1.8 input board. Atmega firmware:20101020 and PIC18F2450 with the latest firmware

Any suggestions?

[kupooglop]

I tried to see your pic, but nothing was there. In my experience false notes come from a short on one or more inputs, or having a very hot piezo input. Look for any shorts you might have. Scrubbing your pcb with isopropyl alcohol or some electronic cleaner is VERY helpful for identifying shorts. Are you using a voltage divider on your piezo? If not, it most likely is too hot. I have eliminated false trigger problems with voltage divider. A good pot is recommended because you can dial it to best results. Aren't you the one that didn't use bat 85 Schottky barrier diodes? Whatever diodes you used might not properly clamp your piezo signal and your muxrs are getting blasted and sending false notes.

[timekeeper]

I tried to see your pic, but nothing was there. In my experience false notes come from a short on one or more inputs, or having a very hot piezo input. Look for any shorts you might have. Scrubbing your pcb with isopropyl alcohol or some electronic cleaner is VERY helpful for identifying shorts. Are you using a voltage divider on your piezo? If not, it most likely is too hot. I have eliminated false trigger problems with voltage divider. A good pot is recommended because you can dial it to best results. Aren't you the one that didn't use bat 85 Schottky barrier diodes? Whatever diodes you used might not properly clamp your piezo signal and your muxrs are getting blasted and sending false notes.

Link fixed.
Thanks for the reply. The activity I am mentioning appears even with no piezo connected! I was sure I had double checked all my soldering but it appears I have to go all over again. The muxers I use (4851) need no diodes!

[dmitri]

Judging from the image all notes have number 63. It is definitely not a default note number for a HiHat on any zone. So it can be one or combination of these:

1. you misconfigured MegaDrum - load default settings.
2. you have shorts in the Analogue part of the board.
3. you have breaks on the ADC's inputs or resistors.
4. you have faulty MUXers.

[timekeeper]

Judging from the image all notes have number 63. It is definitely not a default note number for a HiHat on any zone. So it can be one or combination of these:

1. you misconfigured MegaDrum - load default settings.
2. you have shorts in the Analogue part of the board.
3. you have breaks on the ADC's inputs or resistors.
4. you have faulty MUXers.

Thanks for the reply!

1. I haven't played with setting, so it's pretty much the default ones...
2. I have checked, now I 'll do it again...
3. what is ADC?
4. I doubt but I 'll try new ones (thankfully I have bought quite some spares).

[dmitri]

3. what is ADC?

Analogue inputs, pins 33-40 of Atmega.

[timekeeper]

3. what is ADC?

Analogue inputs, pins 33-40 of Atmega.

I 'll check it tomorrow and report back. Thanks man.

[jman 31]

If you can, please post a clear picture of your board top and bottom, and also wash your board very well with soap and water to get all the flux and microscopic pieces of solder off. You can also use isopropal alcohol to get it very clean. Many times it is just something that you can't see that is messing things up.

[timekeeper]

If you can, please post a clear picture of your board top and bottom, and also wash your board very well with soap and water to get all the flux and microscopic pieces of solder off. You can also use isopropal alcohol to get it very clean. Many times it is just something that you can't see that is messing things up.

I won't post a picture of the board because it might scare you off!!! Haha!!! Thanks for your interest man!

[timekeeper]

I thoroughly cleaned the pcb board with flux removal. At vain... The problem still exists. Seem there is a short somewhere. I will remove all muxers and then I 'll try to pinpoint the one causing the problem.