Howdy thisisit,
sorry for the late reply….busy weekend.
I’m going to be inquiring at my local maker-space this evening about the availability of an oscilloscope. In lieu of that, I have my eye on a Tektronix TBS1052B-EDU 50 MHz, 2 Digital Channel Oscilloscope at Amazon or a PC-based unit. So, what we’re looking for with the scope is not necessarily specific data that is being exchanged on any particular data line, but merely the quality of the signal being exchanged. Specifically, I want to see nice edges from all address and data lines (i.e. – google+images “square wave”) and no signals that look like they are ramping up to near Vcc (i.e. – google+images “capacitor charging square wave”). If there is something up with a data line or multiple lines, trace it/them until you find the issue. It’s quite possible to find solder bridges that tie data lines together or a data line to some other part of the circuit. Solder bridges love to hide under connectors and other parts. If all of the µC pins look OK, I would measure all of the MOVs (V0-V9) for resistance and also remove the LCD and see if the valves actuate using the web interface. My next step would be to start isolating the sections I mentioned in my last post. Depending on your skill with a soldering iron, you could easily lift pins to the µC on IC5, IC4, U1, IC3 & resistor RQ (in that order). Post back your findings and if you have any more questions.
Good Luck