www.megadrum.info

Hello all, this is my first post, but I have build 2 Megadrums from Dmitri's schematics already (first one had some broken tracks on both PCBs but worked, so I decided to rebuild both boards from scratch).

What is happening now with the new boards is that I get no input from my triggers (notice that I did get them on the old build). Injecting 5V into the analog board's resistors I get responses on the LCD, albeit most of them trigger 3 inputs at the same time (just tested this so I didn't write down which ones). I checked both boards for shorts and broken tracks, but not very thoroughly, since I need new glasses and was getting headaches from straining my eyes!

So, the question is: Should I check for shorts on the analog board, the digital board, check my 4051 multiplexers (I have a few spare ones, but I don't believe they are the problem) or just re-etch the analog board and do it all again? This might be a problem since I bought all BAT85s at the only store that carries them here and they don't know when they'll get more.

My LCD works, USB MIDI works (tested with MCT and rubbing fingers on the analog board's resistors ), buttons work. No rotary encoders, no 6N138 since all I could find here were 6N136 and 6N137, MIDI LED doesn't work but might be the LED that I got from the spare part bin and didn't test.

All in all I'm really exited about Megadrum and what I could test with my previous working boards, and I'm very thankful for Dmitri's great work. I just don't want to re-etch my analog board's PCB if the problem is with the digital one, or vice-versa.

Oh, the 40 wire flat cable is tested working with the previous board.

So, HELP! =D

And thank you all for all the time and work you put into this!

OK, I have tested it again. Apparently it wasn't all inputs dead. Here's what I've got:

Hihat input: dead
Bass input: works
Snare: dead
Ride: tip - the 2nd, 3rd and 4th bars on the top come up / ring - the 2nd, 3rd and 4th on the bottom come up
Crash: works
Tom1: dead
Tom2: dead
Tom3: tip - the 7th and 8th bars on the top come up / ring - the 6th, 7th and 8th on the bottom come up
Tom4: tip - the 9th bar on the bottom comes up / ring - the 9th bar on the top comes up (maybe I soldered them reversed? it's possible)
Aux1: dead
Aux2: dead
Aux3: tip - dead (did get something at first but then went dead) / ring - 10th, 11th and 12th bars on the bottom come up
Aux4: tip - dead / ring - works
Aux5: dead
Aux6: dead
Aux7: tip - 13th, 14th and 15th bars on the top come up / ring - 13th, 14th and 15th bar on the bottom

So I'm guessing either massive malfunctions on the digital board, damaged BAT85s (I salvaged most from the previous board) or some stupid short I missed on the analog board. I'm not very good at following schematics, but maybe from this someone can tell something.

Maybe I'm just being stupid, but either way tell me, since I don't know how to test for the first 2 ones and checked the boards from shorts 3 times already

Nevermind, found a hairline short on the analog board between the tracks to 2 of the muxes pins.
Having a constant (62 - 64ms apart) full velocity hit on Tom2 head, I'm guessing another short?
Thank you all for your patience, hopefully I'll be able to bring something back to you instead of only problems! =D