Re: QCX + Microcontroller #problem

Mike Easterbrook

My QCX is running on 6x1.5 v AAA and LCD is fine

On Sun, 16 Aug 2020, 23:20 Christopher Broholm, <kc3mgf@...> wrote:
I don’t have an oscilloscope so I feel a little limited in the amount of testing I can do. I do have a multi-meter though but I’m not sure how useful that is. I’ve checked and fixed a few solder joints here and there but still no luck. Could it be that I’m supplying it with 9v rather than the recommended 12v? 

On Aug 15, 2020, at 18:00, Arv Evans <arvid.evans@...> wrote:

Something is causing the LCD to not be initialized.  It could be a bad solder joint,
something shorted, a defective LCD, a defective component, a component installed
wrong, or in the wrong place.  It could even be bad power.

Detailed analysis of what does work versus what does not work is suggested.  This
would involve as much testing as you have test equipment to perform.  A chart of
what tests you have performed could help avoid repeating the same tests later.

Electronics circuits that fail require a well thought out procedure to determine what
works and what does not work.  Sometimes it can be even more involved than was
the original design.

I would start by using the schematic to locate all places where power is fed to a
component and document the power at each location.  Next check the voltage
at each pin of the LCD to insure that each lead that should be getting data is
getting data during the initialization phase.  An oscilloscope is useful here, but
a DVM can also be used to look for voltage changes to indicate that data is flowing.

It might be a waste of time and money to replace components before you have
definitely proven them to be defective.


On Sat, Aug 15, 2020 at 3:34 PM Christopher Broholm <kc3mgf@...> wrote:
So today I finished building my first QCX+ aaaaand it didn’t work. The good thing is that I’m pretty sure I know why. The problem is that I soldered the IC2 microcontroller chip straight on the board (without the socket.) Now when I turn it on, I just have the top row of solid blocks. My question is this: Am I right in thinking it’s the microcontroller being soldered straight on the board without the socket that’s the problem/it’s damaged? The second question is: Is it salvageable? Would I theoretically be able to buy a new IC2 chip, remove the old one,  install it correctly with the socket this time? I’m really hoping it’s just a matter of replacing the IC2 microcontroller and not a matter of rebuilding it D:


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