NOTE: Sorry about the dead links to the forum. I'll keep working on that.
BOM
PSU Section
- You will need to pay attention while building the PSU, and if you had already ordered
the transformer from Digikey you'll find that it is rated a bit high for how much
voltage we actually need. For the sake of the regulators it is best to order the proper
transformer (Amveco 62063)
- The fuses on the original parts list are rated for too little current, see this thread for details:
http://eight-oh-eight.org/phpbb2/viewtopic.php?t=152
- You need to change how one of the 1n400* diodes is soldered into place in order to reduce
the voltage at the input of the LM7805 (5v regulator). This provides an important improvement
to the reliability of the circuit. Details can be found in the PSU construction thread here:
http://eight-oh-eight.org/phpbb2/viewtopic.php?t=41
with a picture of the proper mod here:
http://www.eight-oh-eight.org/Pics/MB808_PSUMod.jpg
- You also need to take care with the PCB spacer which is placed closely to the AC-IN header.
I recommend running a ground wire directly from this point to be absolutely sure of safety.
(Note: if you use washers and nuts on the potentiometers to hold the pcb to the front panel,
you can leave that spacer completely out. -Doug)
Sequencer Section
- Take care when soldering the components into this part of the board. The Ground plane is on
the same side as the solder pads and there is only the smallest of spaces left between them.
Small solder bridges can appear here and are very difficult to find when it is a whole section
full of components which are suspect. Solder is small areas at a time and then check for
continuity between 5v and GND and, if you want to be really sure (perhaps you don't have an oscilloscope) then check each solder joint against GND.
- In order to use all the LED's in TK's MB808 firmware you need to make some changes to the
connections as shown here:
http://www.ucapps.de/midibox_808/led_fix.jpg
TK used individual resistors instead of resistor arrays (they are the same thing), and the two
pins need to be lifted because their pads on the PCB are connected to ground. (Note: if you haven't
soldered in the IC sockets yet, you can cut the traces on the pcb. See the DOUT thread for more info
-Doug)
The wires are connected to the LED's for the Alt and Shift buttons. See the DOUT post for details:
http://www.eight-oh-eight.org/phpbb2/viewtopic.php?t=46
Trigger LED Section
Noise Section
CP Section
- C85 has it's polarity reversed! Solder the negative lead towards the + marking on the silkscreen.
CY Section
HH Section
Main Out Section
- Do not solder in the 2SK30 FET transistor.
Errata for Batch 2 PCB's
BOM
- There have been numerous changes to the official parts list, be sure to get the most up to date version here
(as of March 20, 2008, we're at version 4.9):
http://www.eight-oh-eight.org/Parts
PSU Section
Core Section
DOUT Section
Sequencer Section
- In order to use all the LED's in TK's MB808 firmware you need to make some changes to the connections as shown here:
http://www.ucapps.de/midibox_808/led_fix.jpg
TK used individual resistors instead of resistor arrays (they are the same thing), and the two pins need to be lifted
because their pads on the PCB are connected to ground. (Note: if you haven't soldered in the IC sockets yet, you can
cut the traces on the pcb. See the DOUT thread for more info -Doug)
The wires are connected to the LED's for the AUX and Shift buttons. See the DOUT post for details:
http://www.eight-oh-eight.org/phpbb2/viewtopic.php?t=46
Trigger LED Section
Noise Section
CP Section
- C85 has it's polarity reversed! Solder the negative lead towards the + marking on the silkscreen.
Main Out Section
- Do not solder in the 2SK30 FET transistor.
