Well,
I've tried various ways of simulating the load/coupling/injection etc of the programming input, and still no downloading of dataset. I've scoped the serial data from the PC through the immediate input circuit on the meter, including two Toshiba P181GB SMT SOP4 photo-couplers, right up to the main PIC 16F877 micro-processor chip, and everything seems normal. There does not seem to be any output from the PIC, ie as a response to the serial port request, and possibly there is a PIC chip fault, or support circuitry. [Although other functions of the chip seem normal, power-on, data selection, LCD drive, RF/channel/Freq selections].
I've looked at the RST line, and seems to be functioning, so we may not have a low part-count-repair, short of system replacement.
Already wasted too much time on this, unless we have someone else's insight on this, this one's going back on the shelf.
Guys???
Thanks for help anyway, Zac.... |