AwDeOh's Megadrum build.

[AwDeOh82]

Hey guys,

90% finished soldering my V2.8 board together, once that's done I'll get the LCD and everything else done. pics to follow when I find my good camera. Just wanted to stop and ask a few questions.

I have 2 spots left to solder something to - '1mH' and 'R lcd'. I also have 4 diodes left, and not 100% sure where to put them:

Brown Black Brown Gold = 100
Yellow Violet Black Gold = 47
Yellow Violet Brown Gold = 470
Red Red Brown Silver = this one is fatter than all the rest

My first guess is that the fat diode above goes to the '1mH' position - on the Synthex 2.7 board, there was a fat diode in the same position, but I think the color bands were different.

My second guess is that the component might be different in 'R Lcd' position depending which LCD you ordered with the kit? I'm using the White Characters, Blue Background LCD.

Also, the 1N4148 can color coded with a thicker yellow band at one end - I've soldered then all with the thick yellow band facing in to the middle of the board (the band end of the diode is facing the Atmega32 slot in all 3 cases - is that correct?

[Synthex]

On "1mH" spot, you can put the "Red Red Brown Silver" components, it's an inductor of 220uH.

For the LCD, you can use for the "R lcd" :
- A 100 ohms resistor for the White characters Blue background LCD
- A 470 ohms resistor for the Blue characters Black background LCD
- A 47 ohms or less or no resistor for the Green characters Black background LCD

All 1N4148 diodes are well soldered.
The thick yellow band (or black band) must be facing the square pad.

[AwDeOh82]

Alrighty!

I've got it all soldered together now, attached the LCD and key buttons. When I plug it into the USB port I get the 'Megadrum.info - D. Skachkov (C)' screen, followed by the VU meter screen. Left/Right/Up/Down all work, only thing I've noticed is a slight latency when switching through the menu, I'm not sure if that's intended or not. Everything appears to be fine on Megadrum's side, but I'm only guessing that because the menu seems to function correctly.

But!

It comes up as an unknown device in both notebooks I've tried, one running XP, and my main one running Vista Home, both are all legit and updated. The MCT program won't recognize any MIDI Input devices as being installed, nor will EZDrummer (through Toontrack Solo). I've searched around the forum, and none of the threads that came up seem to be the same as this. Any ideas?

[dmitri]

One of these in the order of probability:

1. Bad soldering/shorts around PIC18F2550.
2. Incorrect crystal for PIC18F2550. It must be 12Mhz.
3. PIC18F2550 is not programmed.
4. PIC18F2550 is faulty.

[Synthex]

Do you use the 16 MHz crytal for the Atmega ?
Have you tried another USB cable ?

[AwDeOh82]

Do you use the 16 MHz crytal for the Atmega ?

I used the 20Mhz crystal, I wasn't sure of which to choose, so I went with 20Mhz. Should I change this over to the 16Mhz, or is it possible that I've already caused some damage by using the 20Mhz?

I did use the 12Mhz crystal for the PIC18F2550 however.

The kit came from Synthex, so I'd assume the PIC18F2550 is programmed, there's always the possibility that it was damaged when I put it into the socket. I can't see any bad soldering, but again, there's always the possibility of a problem in the soldering. As for the cable, it's the one I use for my Line 6 Pod XT, apon testing it on the Pod it doesn't appear to have any problems.

[AwDeOh82]

Just to test things, I put the 16Mhz in place of the 20Mhz and it works! No 'installing USB device' or anything like that, I just plug it in and it becomes available in EZDrummer, MCT and everything else. Thanks for the help Synthex and Dmitri

I'll do some testing then put it all together, when I know it works 100% I'll start posting a guide for utter neophytes like myself.

[AwDeOh82]

Okay, I'm nearly finished, been waiting for all the jack sockets and things to arrive. I have a couple of issues. Please bare with a possibly over explained question that might not make sense.. I've been trying to figure this out for a couple of hours, having already spent about 8 hours before that soldering and cutting holes in the case for everything - so my brain is fried.

I've desoldered the USB socket because space to mount the board is tight, I'll have to mount the socket elsewhere and use the 4 pin connector behind it. I have a 4 wire version of the 5 wire cable used to connect the push button keys, colored Yellow Orange Red Brown. Assuming that the Yellow cable will be towards the + marking on the PCB board (next to the LCD connector), could someone advise me which color needs to be soldered where? I've had two attempts at this so far, the first time the LCD lit up but didn't display anything, the second time it lit up and kinda flashed. I'm guessing unless I'm lucky, I may have already fried something on the board...

In the pic below, the bottom right diagram shows the underside of the socket. In the two attempts I made earlier, I'd soldered (clockwise from the top-left pin) Y, O, R, B, and then Y, O, B, R. It'd be easiest if someone is able to list the correct colors like that, clockwise from the top-left pin.



Next - when I plug a trigger into the Crash, Tom 4 and Aux 6 inputs, they start rapidly triggering. I've checked the input sockets, and everything appears normal - I can't see any bad soldering or wires in the wrong place, and all the other inputs work correctly. Has anyone run into this?

[Synthex]

All is in the PCB v2.8 Quick Manual v2.pdf

some_pinouts.gif

[AwDeOh82]

Yup, I've worked off those pictures - got my camera working, so hopefully the pics explain where I'm up to. Assuming that Pins 1 & 2 are at the back (when you're looking at the input of the socket), and Pins 3 & 4 are at the front, my wiring is as follows (shown in the first pic):

Pin 1 - Yellow - VCC 5V
Pin 2 - Orange - D-
Pin 3 - Red - D+
Pin 4 - Brown - GND

Second pic shows the cable plugged in, Yellow towards the LCD ribbon, Brown towards the USB jumper. When I tried the first time, I'd accidentally wired Pins 3 & 4 the opposite, so the board was getting D+ on the GND pin and vice versa (I'm including these details incase either way has fried something, I'm hoping not). So either way, as it is now or with 3 & 4 reversed, it doesn't work - I just get a bright pulsing LCD Screen.

Any ideas?