AwDeOh's Megadrum build.

[dmitri]

Reverse power polarity may have damaged some or all ICs. If the USB socket is going to be external to the board and you're not sure about USB wires numbering the right way to do it is:

1. solder USB socket.
2. power it up over USB without ICs in their sockets and then checking right polarity on power rails/pins.
3. mount all ICs.

[AwDeOh82]

Okay. As it stands now, is the wiring in those pictures correct?
And if the wiring is correct, and all I get is the LCD lit up and kinda pulsing (no startup Megadrum text or VU), would that indicate IC damage?

[dmitri]

Okay. As it stands now, is the wiring in those pictures correct?

The best way to test it is to use a meter to test continuity between pins of the USB socket and the pin holes for this socket on the board.

And if the wiring is correct, and all I get is the LCD lit up and kinda pulsing (no startup Megadrum text or VU), would that indicate IC damage?

It's hard to tell. You may have damaged the LCD as well or you can have shorts/breaks on the board.

[Synthex]

Okay. As it stands now, is the wiring in those pictures correct?
And if the wiring is correct, and all I get is the LCD lit up and kinda pulsing (no startup Megadrum text or VU), would that indicate IC damage?

the wiring in those pictures is correct.

[AwDeOh82]

As far as shorts/breaks on the board, everything seems to be working fine except the 3 inputs that start rapidly triggering nonstop when you plug a pad in.

I should have bought a multimeter before I started the project, if I had one I wouldn't have had any problems with the USB thing. If I get a hold of one, are there tests I can do on the IC's and LCD to check whether they're damaged?

If worse comes to worst I'll buy a new LCD and IC's. I half expected I'd fry *something* along the way, being my first project.. call it collateral damage.

[dmitri]

As far as shorts/breaks on the board, everything seems to be working fine except the 3 inputs that start rapidly triggering nonstop when you plug a pad in.

What do you mean by "start rapidly triggering"?

I should have bought a multimeter before I started the project, if I had one I wouldn't have had any problems with the USB thing. If I get a hold of one, are there tests I can do on the IC's and LCD to check whether they're damaged?

With a multimeter it is impossible to test if the ICs have failed or not. They may still be ok although very unlikely.

If worse comes to worst I'll buy a new LCD and IC's. I half expected I'd fry *something* along the way, being my first project.. call it collateral damage.

Sorry it happened. It is good you realise that with DIY things may go wrong but I'm sure you'll have your MegaDrum working after all.

[AwDeOh82]

What do you mean by "start rapidly triggering"?

I got the input section wired up and tested it yesterday, before making my post about the USB problems - when I plugged my pad into the Crash, Tom 4 and Aux 6 inputs (in EZDrummer, all the Aux inputs default to the Hi-hat), as soon as the jack was plugged into the sockets in question, the sample would start repeatedly triggering very quickly, without me touching the pad at all. Best way to explain it would be that the sample started triggering by itself, as though a drummer was playing an insanely fast double stroke roll on the pad. It only stops when I unplug the pad. All the other inputs acted normally. I've inspected all the soldering, all wires are in the right place and soldered well. I found this problem before I started working on the USB. I'm guessing here.. but based on not being able to find anything wrong with the wiring, could this have been a problem with the IC's?

Bare in mind here that I could have easily damaged an IC or another component along the way as I installed it, or from generally handling the PCB...

---

As for the USB power problem, currently when I plug the Megadrum in, the LCD lights up and all the 32 blocks on the screen are blinking on/off quickly - there is no Megadrum/Dmitri text on startup. The LCD itself *seems* fine to my eye, the backlighting and the 32 blocks look normal - I'm not expert but it doesn't appear obvious that the LCD is damaged. I also don't get any response on the LCD from using the keys. Windows recognizes Megadrum being plugged in, and EZDrummer recognizes that Megadrum is available, but I can't get any further response - I'm not getting any MIDI notes coming into EZDrummer by playing the pad.

So.. where to from here? Is there anything I can do to check whether the IC's are damaged, or does the evidence above pretty much make that obvious?

I'm guessing I need to ask Synthex really nicely if he has any replacement IC's available?

[dmitri]

What do you mean by "start rapidly triggering"?

I got the input section wired up and tested it yesterday, before making my post about the USB problems - when I plugged my pad into the Crash, Tom 4 and Aux 6 inputs (in EZDrummer, all the Aux inputs default to the Hi-hat), as soon as the jack was plugged into the sockets in question, the sample would start repeatedly triggering very quickly, without me touching the pad at all. Best way to explain it would be that the sample started triggering by itself, as though a drummer was playing an insanely fast double stroke roll on the pad. It only stops when I unplug the pad. All the other inputs acted normally. I've inspected all the soldering, all wires are in the right place and soldered well. I found this problem before I started working on the USB. I'm guessing here.. but based on not being able to find anything wrong with the wiring, could this have been a problem with the IC's?

It could have been because of bad wiring, bad ground. Now it's hard to tell.

Bare in mind here that I could have easily damaged an IC or another component along the way as I installed it, or from generally handling the PCB...

---

As for the USB power problem, currently when I plug the Megadrum in, the LCD lights up and all the 32 blocks on the screen are blinking on/off quickly - there is no Megadrum/Dmitri text on startup. The LCD itself *seems* fine to my eye, the backlighting and the 32 blocks look normal - I'm not expert but it doesn't appear obvious that the LCD is damaged. I also don't get any response on the LCD from using the keys.

LCD has ICs inside which could have been damaged.

Windows recognizes Megadrum being plugged in, and EZDrummer recognizes that Megadrum is available, but I can't get any further response - I'm not getting any MIDI notes coming into EZDrummer by playing the pad.

So USB is working. That means that PIC18F2550 is very likely not damaged.

So.. where to from here? Is there anything I can do to check whether the IC's are damaged, or does the evidence above pretty much make that obvious?

Disconnect the LCD. While monitoring for MIDI activity in MIDI-OX (or your sampler) with MegaDrum selected as MIDI In, touch pins 37,38,39,40 of Atmega (one at a time) with something metallic, e.g. tweezers.
Does MIDI-OX show any MIDI activity?
If no MIDI activity, take 4851 ICs out of their sockets and touch pins 37,38,39,40 again. Still no MIDI activity?

[AwDeOh82]

No MIDI activity is registering either with, or without the 4851's.

[dmitri]

No MIDI activity is registering either with, or without the 4851's.

Atmega is most likely damaged.