(true)MIDI USB Board

[dmitri]

Better be quick, I'm about to go to bed.

[estregan]

Better be quick, I'm about to go to bed.

You go get your rest. Don't want to bother you too much with this as I cant do this quick since my partner is not here who's really the one doing the soldering. I can do it but I'm slow. Let's communicate again when you wake up. Thanks.

[dmitri]

Next time I'll be able to help will be tomorrow after 19:00 which, I guess, means 03:00 in the morning your time. I'll wait 15 more minutes.

[estregan]

1. Disconnect wires 2,3 and 6 of the USBExt connector. Place PIC18F2550 into the socket, power it up. Is the voltage on the pin 14 still not 3.3v? Is the IC still getting hot? If so, go to step 2.

Voltage still not 3.3v but only 1.4v and IC still gets hot.

2. Disconnect C4. Measure voltage on the pin 14 again. Is it 3.3V?

Same result, voltage measured is +1.4 and IC still gets hot.

[dmitri]

1. Solder C4 back in.
2. Disconnect R5, C1, C2 and X1. Is voltage on the pin 14 still not 3.3V? If so, go to step 3.
3. Do you have a spare PIC18F2550? If yes, try it now instead. Still no 3.3V on the pin 14 and the IC gets hot?

[estregan]

1. Solder C4 back in.
2. Disconnect R5, C1, C2 and X1. Is voltage on the pin 14 still not 3.3V? If so, go to step 3.

Voltage measured still +1.4 only. IC still gets hot.

3. Do you have a spare PIC18F2550? If yes, try it now instead. Still no 3.3V on the pin 14 and the IC gets hot?

Sorry, I don't have a spare PIC18F2550, I just order it from abroad as its not available locally, plus its a bit expensive.

[dmitri]

Have a look at it: you effectively disconnected everything from PIC18F2550's pins except power. Why would it still get hot? I see only two reasons.
1. There is still a shortcut somewhere
2. PIC18F2550 is fried, which can be a result of existing/previous shortcut.

[estregan]

Have a look at it: you effectively disconnected everything from PIC18F2550's pins except power. Why would it still get hot? I see only two reasons.
1. There is still a shortcut somewhere
2. PIC18F2550 is fried, which can be a result of existing/previous shortcut.

Ok. I will try to build a new digital board and report back what happens asap. I will also try to source new PIC18F2550.

I saw some PIC18LF2550 on ebay will those work as well?

I'm kind of confused where the problem may be coming from since I got the AVR-CDC to already work. Wouldn't that be enough indication that the digital board is working? Or do I have to build a new USB board as well?

Anyway, back to the drawing board for me.

[dmitri]

PIC18LF2550 will work fine.
If MegaDrum works with AVR-CDC USB board than there is nothing wrong with the Digital board.

[estregan]

While my friend was here, he tested the PIC18F2550 pins 19 and 20 and they are shorted (zero resistance). Maybe that has something to do with it getting hot. Is your IC's pin 19 and 20 also shorted?

Oh well, maybe its already busted. Just have to wait for the replacements to arrive!

Happy Holidays!