After finishing construction of the QCX+, I have the "row of black squares" issue.
I followed the troubleshooting section and read through various group messages.
I traced all the relevant pins from IC2 to the display board header using an ohm meter:
IC2-2 LCD D4 JP4-5 DispHeader 11 continuity good
IC2-3 LCD D5 JP4-6 DispHeader 12 continuity good
IC2-4 LCD D6 JP4-3 DispHeader 13 continuity good
IC2-5 LCD D7 JP4-4 DispHeader 14 continuity good
IC2-6 LCD EN JP4-1 DispHeader 6 continuity good
IC2-8 GND continuity good
IC2-20 AVCC R61-1 continuity good
IC2-22 GND continuity good
IC2-27 LCD RS JP3-4 DispHeader 4 continuity good
Sadly, I do not have an oscilloscope.
I measured voltages with a volt meter while the rig was powered up:
IC2-1 not(RESET) 4.38V chip not being held in reset
IC2-2 LCD D4 JP4-5 DispHeader 11 4.90V
IC2-3 LCD D5 JP4-6 DispHeader 12 4.90V
IC2-4 LCD D6 JP4-3 DispHeader 13 4.90V
IC2-5 LCD D7 JP4-4 DispHeader 14 4.90V
IC2-6 LCD EN JP4-1 DispHeader 6 0.00V LCD is disabled???
IC2-7 VCC 5.00V correct supply voltage
IC2-27 LCD RS JP3-4 DispHeader 4 3.55V LCD is being held in reset???
I checked if LCD EN was shorted to ground and it was not. I also checked to see if any data pins were shorted together and they were not.
Assuming the sense of LCD EN and LCD RS are as marked on the schematic, IC2 is disabling the display and holding it in reset. That does not seem like proper behavior if IC2 has booted and it executing code. While I realize that volt meter measurements on serial data lines is inconclusive at best, it sure seems that there is an issue with IC2.
What else should I test before ordering a replacement?
73, Mike KK7ER