Friends,

I apologize if this a duplicate but I never saw the message nor any response.

I am struggling with my QCX kit.? I have finished construction and tried to align the radio.? I get a single row of LEDs across the top.? The contrast adjusts normally.

I spent some time measuring some of the voltages in the manual.? I did get some anomalous results.? The measured value is first, the manual value is second.

C45 1.29V? -? 2.44V
C46 0.78V? -? 2.30V
LCD Pin 4 3.48V? -? 4.92V
LCD Pin 7 thru Pin 10 4.88V? -? 1.08V
LCD Pin 11 4.88V? -? 0.00V
LCD Pin 14 4.88V? -? 0.00V

I have carefully checked my soldering work several times under a high power magnifying light and lens.

Could this be one of the bad chips mentioned recently?

Any thoughts or suggestions would be most gratefully received.

Jeff
WV9X

开云体育

Jeff,
In the absence of anybody else's comments
you have to put up with second best, I have yet to build a QCX.....? :-)


(As I understand it,
the blank AVR is configurable to use either an internal, or external reference Osc.
By default it is configured to internal, however when used in the QCX Hans has opted to use a 20MHz crystal for greater accuracy and is selected as a result of the program data.)


Assuming the Micro has all it's other dependencies and has correctly entered it's running state, the 20MHz xtal should be active in a QCX.
Therefore a possible test is:-
Can you receive the 20MHz xtal on a general coverage receiver with a piece of wire placed close to the QCX?
(The troubleshooting guide advises against directly measuring the xtal freq as stray capacitance / loading may kill the osc.)
If the 20MHz xtal is not osc then I would start questioning if my IC was number 7 in the tube........

While I'm at it I would measure the 27MHz xtal attached to the Si5351, the same way both should be running.


Perhaps someone who has an affected QCX can pass on their findings?


Alan

Jeff

With so many bias voltages astray, please check orientation of polarized capacitors, diodes and ICs.something seems amiss.

Curt

Thanks to both Curt and Alan.

I will continue to investigate.

73
Jeff

Same here Jeff

Did you find a solution?

73s Ted
M7ECH

What is voltage on pin 7 IC4

On Tue, Nov 27, 2018 at 10:20 PM, Chopper wrote:

What is voltage on pin 7 IC4

Thanks Chopper
2.54v?
It is a rev 4 board
Best Ted