Topics

QCX stopped working #qcx #problem

Chad Lawrence
 

I have a 40m qcx that I bought assembled. 3 or 4 times over the last month I've had a weird issue pop up where my screen displays "random" characters instead of the frequency and such. Turning it off and on would be better, but still not quite normal. Not all the menu options would display correctly, but enough I could factory reset. Doing a factory reset would fix it for a few days. Until it would go "random" again. Tonight I had the same thing happen, while listening my screen switched to weird characters, I turned it off and on, but now I have no display at all. It lights up blue, but displays no characters at all. It seems to still work otherwise, i can tune to stations and such, and I was able to reset it by counting key clicks, but still no display. I'm assuming I managed to reset it based on the key is now straight instead of iambic b... I tried adjusting the display pot, and the contrast changes but still nothing displayed. Any ideas? If I can figure out how to attach a pic I'll show the random characters...

Chad Lawrence
 

This morning I powered up the QCX and the display is working again. The radio was factory reset, so that worked. I'm guessing the "random" screen will happen again, any ideas on testing if it's a screen problem or a CPU/component issue? Thanks

Alan de G1FXB
 

If it's on a mains derived power supply, Noisy / Unstable ?

If possible try it on a suitable battery,

otherwise just because it was purchased pre-built there still  could be adjacent components touching / bad solder joint.


Alan


On 18/05/2019 13:05, Chad Lawrence wrote:
This morning I powered up the QCX and the display is working again. The radio was factory reset, so that worked. I'm guessing the "random" screen will happen again, any ideas on testing if it's a screen problem or a CPU/component issue? Thanks

Jack Brabham - KZ5A
 

Works for a while and quits, then recovers after being "off" for a while sounds like something getting hot and failing.  The 7805 regulator would be a prime suspect.

73 Jack KZ5A


On 5/18/2019 6:10 AM, Alan de G1FXB via Groups.Io wrote:

If it's on a mains derived power supply, Noisy / Unstable ?

If possible try it on a suitable battery,

otherwise just because it was purchased pre-built there still  could be adjacent components touching / bad solder joint.


Alan


On 18/05/2019 13:05, Chad Lawrence wrote:
This morning I powered up the QCX and the display is working again. The radio was factory reset, so that worked. I'm guessing the "random" screen will happen again, any ideas on testing if it's a screen problem or a CPU/component issue? Thanks


Kelly Breed
 

Have you checked all your solder joints and connections to the display? 

James Daldry W4JED
 

Sounds like you have a static electricity problem. I've had similar happen here, since the antenna jack is connected to "ground ground" but not any of the electronics. My front panel is connected to the shafts of both the volume control and the encoder. A static spark on the volume control would just make a pop in the audio, but in the encoder would upset the microprocessor. Same for the key jack. Since the chip is programmed by forcing charges through insulators, a little extra force could upset a number of gates.

Probably the simplest way to handle this is to touch the antenna connector before touching anything on the radio.

Back in the late '80's and early 90's Toshiba made a bunch of TV's with the micro under the CRT, about 2 inches back from the front. After the set ran a while static would build up on the CRT glass and "pop" to the micro. The set would keep running, but the onscreen display would start swearing at you. The fix was to replace the micro and add a grounded strip of copper to the top of the micro.

73

Jim W4JED

On 5/17/19 11:13 PM, Chad Lawrence wrote:
I have a 40m qcx that I bought assembled. 3 or 4 times over the last month I've had a weird issue pop up where my screen displays "random" characters instead of the frequency and such. Turning it off and on would be better, but still not quite normal. Not all the menu options would display correctly, but enough I could factory reset. Doing a factory reset would fix it for a few days. Until it would go "random" again. Tonight I had the same thing happen, while listening my screen switched to weird characters, I turned it off and on, but now I have no display at all. It lights up blue, but displays no characters at all. It seems to still work otherwise, i can tune to stations and such, and I was able to reset it by counting key clicks, but still no display. I'm assuming I managed to reset it based on the key is now straight instead of iambic b... I tried adjusting the display pot, and the contrast changes but still nothing displayed. Any ideas? If I can figure out how to attach a pic I'll show the random characters...

Chad Lawrence
 

Thank you all for the suggestions, I will do some investigating and see what I can find.
73
AB8SV

Chad Lawrence
 

I may have it fixed finally. Last night after the "random characters" issue reappeared, I removed the LCD again to check all my header pins for continuity with my multimeter. Everything seemed to check out so I plugged it in, but then had nothing on the display except bars on top row and blank bottom. I let it sit overnight like last time, but this morning it still had no display. I figured the problem must be the connections since unplugging the LCD has made it worse. When I got home from work the display still showed nothing so I reflowed the solder on all the male and female header pins, and bam! She works again! Time will tell if the "random characters" gets solved, but it looks promising. Thanks for the suggestions all. ab8sv