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newly built QCX not working. #qcx #qcx40

Fast hosts
 

Hi All,
Just finished the QCX build and on power up, I get just the top row of squares in the display. Following the suggestions, I checked all solder connections on the microcontroller socket and pulled the chip to find all pins were straight and seating properly.
I am now at a loss.. are there any components other than the microcontroller that would cause the system not to boot? I have a small Chinese DSO138 oscilloscope but i am not au fait with using it to measure the oscillator output at pins 9 and 10 as suggested.
I am not inexperienced in kit building, having built the UBITX successfully and several small Chinese radio kits.
I know Hans says always suspect the component last but I am thinking I may have a duff microcontroller..
Any suggestions are more than welcome
Keith M6OLP 73

Bob Macklin <macklinbob@...>
 

A useful tool for people without a scope or knowledge of how to use one is a LOGIC PROBE.
 
Mouser has one. I is use it when I don't want use my scope.
 
Bob K5MYJ

----- Original Message -----
From: Fast hosts
Sent: Friday, November 15, 2019 8:43 AM
Subject: [QRPLabs] newly built QCX not working. #qcx #qcx40

Hi All,
Just finished the QCX build and on power up, I get just the top row of squares in the display. Following the suggestions, I checked all solder connections on the microcontroller socket and pulled the chip to find all pins were straight and seating properly.
I am now at a loss.. are there any components other than the microcontroller that would cause the system not to boot? I have a small Chinese DSO138 oscilloscope but i am not au fait with using it to measure the oscillator output at pins 9 and 10 as suggested.
I am not inexperienced in kit building, having built the UBITX successfully and several small Chinese radio kits.
I know Hans says always suspect the component last but I am thinking I may have a duff microcontroller..
Any suggestions are more than welcome
Keith M6OLP 73

Fast hosts
 

many thanks.. I have double checked methodology with the scope and using my dd5 function generator to produce a sine wave, I can read that on the scope. Transferring my probes to the oscillators(s) on the QCX, I see no reading..

Alan G4ZFQ
 

I get just the top row of squares in the display. Following the suggestions, I checked all solder connections on the microcontroller socket and pulled the chip to find all pins were straight and seating properly.
Keith

I have a small Chinese DSO138 oscilloscope but i am not au fait with using it to measure the oscillator output at pins 9 and 10 as suggested.
All you need do is put the probe on the pin. The scope just needs to show a signal is there. The problem is that a scope might kill the oscillation.. If that happens have you a radio to listen around 20MHz?
I'm not sure I like Hans' troubleshooting in so far as it puts a lot of emphasis on a scope. Most faults can be found without one, a scope sometimes makes it easier. I've scopes but still do not use one very much.
You have checked voltages?

73 Alan G4ZFQ


I am not inexperienced in kit building, having built the UBITX successfully and several small Chinese radio kits.
I know Hans says always suspect the component last but I am thinking I may have a duff microcontroller..
Any suggestions are more than welcome
M6OLP 73

ajparent1/KB1GMX
 

>>>All you need do is put the probe on the pin. The scope just needs to show a signal is there. The problem is that a scope might kill the oscillation..<<<

Alan,
This is a digital VFO that goes way past 100mhz and scope loading should not be a factor
on an output that can push milliwatts into 50 ohms. If it were some bodgey VFO maybe.

However listening on a known working radio is actually easier.

Allison



--
Please reply on list so we can share.
Off list email goes to trash, I had to due to scrapers.

Fast hosts
 

I have a logic probe arriving tomorrow so will check the oscillators with that 

Fast hosts
 

I do have aN RSP1A SDR which I guess I could use...

Bill Cromwell
 

I agree with Alan, a scope is not needed for everything and there are methods that don't require a scope even when a scope might be useful (if you have one). There are also times when a scope can even be misleading or detrimental. On the other hand, if you also do not have another receiver that can detect the frequencies of interest that method will obviously not help. Perhaps some of the hams building these radios do not have any other receiver or more likely do not have one that covers the frequencies of interest. The first, most important tool is a reliable DMM, DVM, VTVM (all the same tool) and knowing how to use it. Please notice that I used 'reliable' and not that overused word 'accurate'. 'Accurate' comes in degrees and graduations and shades or grey while reliable is absolute. It is reliable or not. After that, voltage, resistance, current readings are useless if you don't have some idea what those readings should be. In early 1952 I didn't know about any of that stuff either, just like people starting new today. But I started then and I am still learning, even if I can already find my way around in activities of various kinds. The underlying principle is "critical thinking" and that needs frequent sharpening and honing. But is is fun:)

Enjoy the journey and..

73,

Bill KU8H

On 11/15/19 12:24 PM, Alan G4ZFQ wrote:
I get just the top row of squares in the display. Following the suggestions, I checked all solder connections on the microcontroller socket and pulled the chip to find all pins were straight and seating properly.
Keith

I have a small Chinese DSO138 oscilloscope but i am not au fait with using it to measure the oscillator output at pins 9 and 10 as suggested.
All you need do is put the probe on the pin. The scope just needs to show a signal is there. The problem is that a scope might kill the oscillation.. If that happens have you a radio to listen around 20MHz?
I'm not sure I like Hans' troubleshooting in so far as it puts a lot of emphasis on a scope. Most faults can be found without one, a scope sometimes makes it easier. I've scopes but still do not use one very much.
You have checked voltages?
73 Alan G4ZFQ

I am not inexperienced in kit building, having built the UBITX successfully and several small Chinese radio kits.
I know Hans says always suspect the component last but I am thinking I may have a duff microcontroller..
Any suggestions are more than welcome
 M6OLP 73
--
bark less - wag more

Fast hosts
 

OK, so when I use an antenna on the SDR I get the 20k oscillator signal proved by turning on and off the QCX. so is it pointing now towards the microcontroller more?

Fast hosts
 

Update... it suddenly started working so might have ben an oxidised contact surface somewhere I cleaned by removing/replacing.
However the boot screen is normal ie "5w CW Tcvr 1.01A QRP labs 2019" but this goes straight to a screen showing "A24,910,00" no select band screen. This is the 40metre version so that VFO is totally wrong although, of course, I should have been offered the opportunity to select my band?

Fast hosts
 

now working and the odd things on boot up solved by a factory reset.. now for some setting up

Fast hosts
 

one more update is that about 50% of the time it will boot to a blank display but powering on and off a few times will usually bring it to life. I did read that to short circuit one or both L5 and L6 can solve this but taking things easily to make sure when it's solved it really is solved and not by luck.