634 desn't react


New member
Last week I bought a 634 20x4 display, it was working fie up untill one moment. The display does not react to any of the commands. What can I check or how can I do to get the display working again.

It's a SKD204-634 V2.2
The backlight is burning
The cables are checked
I checked on 2 PC's
There is nothing visible even no cursor

Please help
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CF Tech

Did you change any connections?

You might have somehow gotten a bad contrast setting stored in the EEPROM.

Try sending:


with WinTest.

Also check that the baud rate switches on the LCD match the baud rate on WinTest.


New member
Checked the baudrate, it is OK...
Tried the \009\000 option, no succes

How I wired the display...
Ground on ground (from pc)
+5V on +5(LCD) (from pc)
+5V on +5(LED) (from pc)
And serial cable form COM1 19200 Baud
USB LCD Displays - Graphic and Character LCDs with a Keypad