JohnSwenson wrote: > Correct, all TOSLINK transmitters that I know about take a standard > digital input and have a builtin LED driver circuit. I don't know of any > that bring the LED pins out directly. That 22.2 ohm resistor is just a > standard thing used to slightly cut down the rise time of the signal to > cut down on ringing when driving a load. > > The cap between VCC and GND is important, but I'm not as sure about the > necessity of the ferrite bead. > > BTW for removing stubborn parts on boards you might want to try ChipQuik > solder. It is sold for removing SMD parts but it works just as well for > through hole ones as well. It is a solder with a super low melting > point, melt blobs of it over the pins and keep the iron moving between > blobs, it will dissolve the original solder and stay liquid long enough > for you to pull the part off. After you get the part off use solder wick > etc. to make sure you get all of this off the board before soldering a > new part. > > This having it wrong on wandboard just reinforces my findings, there is > a curse on TOSLINK transmitters. I have NEVER put one on a board that > turned out right the first time. Including the SWAMP05. I know it's > going to turn out wrong so I quadruple check the spec sheets to make > SURE I get it hooked up right, and it still turns out wrong. And here > the wandboard guys did it as well. It's got to be a curse. We can do 314 > pin monster connectors right, 900 pin cpus right, but these simple > little 3 terminal devices confound us all. It doesn't make sense. > > Actually I think it's the spec sheets. The one for the part on SWAMP05 > has a table that says pin 3 is ground, and the schematic shows pin 1 > connected to ground. Another I looked at shows the pins being labeled 1 > 2 3 in line on the physical drawing, but when listing the functions in a > table they list 1 3 2. If you are not VERY careful in reading this you > can get it backwards. It's sloppy spec sheets that I think are at the > root of the curse. But it's sort of nice to know that I'm not the only > one to have this problem. > > John S.
It is always the simple things that seem to go wrong on the schematic and PCB layout. Number 1 mistake has to be connector reversal. I finally tracked down a copy of the datasheet for the KYT-1150A part that is used on the Wandboard and confirmed that the pinout on the Wandboard is indeed incorrect for this part. Terry ------------------------------------------------------------------------ TerryS's Profile: http://forums.slimdevices.com/member.php?userid=40835 View this thread: http://forums.slimdevices.com/showthread.php?t=97881 _______________________________________________ discuss mailing list discuss@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/discuss
