Topics

QCX Died ...... Sigh #qcx

Rick Williams - VE7TK
 

A few months ago I splashed some solder on the 2-line display of my QCX! The rig worked perfectly but it was annoying having a burn spot in the display. Yesterday I finally installed a replacement.

Well what should have been a simple task has turned into a disaster. I suddenly have the single row of blocks on startup. (Before it's suggested I have done the Schottky diode mod to my Version 2 board AND I have the same problem with the old display. ) Several on/off attempts have not cured the problem.

I dug out my scope and checked the oscillator on pins 9 and 10 of IC2 and there's a nice 20 MHz signal as hoped.

With a 20 MHz output does this suggest that IC2 is likely not the issue? Or am I dreaming in technicolour?

Thoughts appreciated. Thanks,
--
73, Rick
VE7TK

Joe Street
 

This may be obvious but don't forget the LCD bias voltage will vary from display to display.  You may need to reset it.

On Wed, Jun 19, 2019 at 5:25 PM Rick Williams - VE7TK via Groups.Io <ve7tk=yahoo.ca@groups.io> wrote:
A few months ago I splashed some solder on the 2-line display of my QCX! The rig worked perfectly but it was annoying having a burn spot in the display. Yesterday I finally installed a replacement.

Well what should have been a simple task has turned into a disaster. I suddenly have the single row of blocks on startup. (Before it's suggested I have done the Schottky diode mod to my Version 2 board AND I have the same problem with the old display. ) Several on/off attempts have not cured the problem.

I dug out my scope and checked the oscillator on pins 9 and 10 of IC2 and there's a nice 20 MHz signal as hoped.

With a 20 MHz output does this suggest that IC2 is likely not the issue? Or am I dreaming in technicolour?

Thoughts appreciated. Thanks,
--
73, Rick
VE7TK

Rick Williams - VE7TK
 

Thanks for the reply Joe.

Just in case there was an issue like this, I plugged the old display back in and it had the same problem.
--
73, Rick
VE7TK

Richard G4TGJ
 

You should at least try to adjust the contrast.
--
73
Richard
G4TGJ

Rick Williams - VE7TK
 

Thanks for the reply Richard.

Contrast and backlight have been adjusted. Still only one row of blocks. All soldering of IC2, display header and Schottky diode mod checked under a microscope and look good. Continuity of display header to corresponding IC2 pins checked.

Next test is to borrow an ATMega328 with an older version of the firmware.
--
73, Rick
VE7TK