Hi again,
I know this is asking for a big fat “I told you so”, but I’ll throw it in here anyway-
I just built a compact board that I want to use to work on some MB64 apps. Everything but the Core and the LCD are on one big, double-sided, crowded board. The D.In (165) chain is 3 chips long with the last output pulled high. The D.Out (595) is 4 chips with the last hanging open. The A.In is only one 4051. They’ve all got the necessary resistors and the supply and ground pins for each IC have been checked.
Now the weird stuff. I threw all the lines on a single 5x2 pin header. It’s got ground, 5v, sclk, rclk, a line to the 595’s, a line from the 165’s, a line from the 4051, plus the 3 mux lines. The shift register clock/latch lines are jumped in parallel from chip to chip (595’s and 165’s). They all check as solid connections, all linked back to the main header. The IC to IC connections for each chain have also been double checked. Now the dumb part. No sockets. Everything went directly to the board, but was heated as briefly as possible with a low watt iron (23w maybe).
Problem-
Looks like the last two 595’s are not cooperating. I figured to be safe and check a chain at a time, so I went for the LED’s, and only used a five pin cable from my core (at J8) which covers the D.Out data pin, the clock lines, and Gnd/5v. The other chips are onboard and powered up, with the unconnected 165’s still riding the clock/select chain with the 595’s, but I don’t have them, or the 4051 sending anything back right now. For right now, I’m using a button board with it’s own 165’s, that I already know works.
When I power up the core, I get the first four LED’s of the 3rd shift reg. on solid (p.7,6,5,4), as well as the fourth light on the last register (p4). They stay on, and the other eleven outputs for those chips don’t work. The first two register’s lights all look OK.
I know swapping the last two IC’s is the obvious solution, but needless to say, it’s a bit harder to do in real life. If TK, or anyone who knows enough about the serial chain or those IC’s, can think of anything that may cause that type of behavior, it would be a big help. I think I’ll lay off it a day or two to get my nerves back.
The individual out pins to the anodes have all been checked, and the cathodes all hit the resistors to ground (470ohms in my case). I don’t see any obvious shorts on some quick checks (definitely not shorts to 5v or Gnd), but I guess there’s a possibility. I also guess the 3rd shift could be f**king up the 4th one, so I’ll pull that first if I have to. I don’t know if there would be any downside to having three stray 165’s on the clock and power lines if they weren’t connected to the core. I also don’t know how easy it is to cook a shift register by soldering directly to it (well, maybe I do now).
                    Thanks for reading all this crap if you did!
George
PS- I know I probably should have stuck the core circuit on there too and soldered the 18f directly to the board as well, but I wouldn’t want to do anything “stupid”.;DÂ Â Â
