With the backlight on, I can barely read the screen of my QMX. That's with the trim pot turned full counter-clockwise Increasing that trim pot at all, and I can't see anything but the backlight. With the backlight off, screen contrast is quite good, but that's not so helpful in a dark room. Is there any way to fix this?

Oddly this seems to have worked itself out. Backlight contrast was horrible the first day or two of use. I just turned backlight back on and it seems to be good now. Not sure what changed.

开云体育

Maybe a flakey solder joint on the display board?

Weird.? Have you tried adjusting the blue pot to the left of the screen, regardless?

Jason / K1LOL

Yes, I have the trim pot turned full left (counter-clockwise). That's the only position that gives legible contrast.

And it looks like I was premature in saying the problem has worked itself out. After starting up from being turned off several hours, the backlight is back to giving crappy display contrast. It looks like if I turn the backlight on while the QMX is transmitting, the screen can flip back to having good backlit contrast.

I found the culprit! I had the screw securing the corner power supply board too tight, which caused the body of inductor L101 to contact pin #3 on the LCD board. Backing off on this screw just a little bit yielded enough clearance to put things right! Next time I remove the entire unit from the case, I'll flatten the solder hill on pin#3 and/or put a bit of kapton tape between L101 and pin#3. Unfortunately, I misplaced my kapton tape a couple weeks before my QMX build, but until then all seems good.