Re: LCD blank


If R47 is correctly working the contrast of the display then the other issues can be the controller chip on the board IC2 (long chip in socket) or the data lines to the display


So back to basics


Check IC2 is in socket right way round

Check no pins bent (lift the chip slightly and make sure all pins are engaged in socket)

Check chip is fully seated in socket

Check solder joints on Socket (reheat to make sure)

Voltage  VCC pin 7 (5v)

Voltage VCC PAD 7 (5v)

Is chip hot to touch (if yes likely dead)


Check solder joints 20mhx XTAL


The next thing is the socket for the display


Check joints both sides (main board and display board) for bridges and cold joints (reheat and resolder to make sure)


What test equipment do you have? Just a multimeter? Oscilloscope?






From: Wayne Robertson


Thank you; clear now.

So, the gnds and voltages check out yet the LCD is still blank or shows 1 or 2 rows of rectangles, depending on contrast setting of R47.  Anyone have any other ideas, or should I reach out to Hans?

Thanks Julian and Mont.

73, Wayne  



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