Megadrum by Japi - Documentation / Pictures -

[japi]

Pin 40 of atmega and 3 of first multiplexer has good continuity and doesn't seem to short with anything in its path. I also interchanged 4851s number one with number four and still the same.

What else to look ?

Thanks

[scilence]

I had the same problem early on. I found that the jumper wire had a bad weld on it. I de-welded and redid it. Fixed it right up. Hope it might help. If it does it without the ano board connected though i have no idea other then a short or cold solder / bad connection

[japi]

Yes, the issue remains without the IDE cable connected, so is something in the board itself.
I've checked basic things but I couldn't find the trouble.

Thanks!

[gastric]

Japi, now that the holidays have ended I'm about to return to my MegaDrum adventure. It looks like you're still having issues with your DIY 2.5 board. Have you ironed those out? I have one more blank board I can experiment with to create another 2.5 board. But to be honest if yours is still having issues I'll just order a 2.8 from Synthex and expedite my conclusion so I can unsaddle myself from my Trigger IO.

[japi]

Can't decide for you if it's better to order a 2.8 or keep trying, but i'm seriusly considering ordering one, as my time to check and troubleshoot my board is very little

I still have the issue, couldn't find whats causing it, but to be honest, I had very little time to check it deeply. I will do it soon and post back. I guess I will be checking some short or some ground missing in the first 4851 as there is where the trouble seems to be.

[gastric]

Heh, I'm not looking for you to explicitly tell me. I'm just basing my decision entirely on your outcome.

[jman 31]

Yeah me too! I really want to build the entire project, simply to say I did, but I want to know if anyone has a working model before I start!

[japi]

I'm happy to inform that my problem is solved!
Happened to be a trace that joins pin9 of the first 4851 with the others chips. There are 3 pins in those chips that are input selectors, and those go all together between 4851s, I mean, all 9 together, all 10 together and all 11 together (see the datasheet for the 4851 and you'll know what I'm talking about).
The trace was somehow not working, but looking ok. I applied some solder near the problematic point, and bingo, had continuity again and problem solved

Here's a picture of the problem (sorry about my photoshop skills hehe)

problem.jpg

Japi (Megadrumming again!)