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Another single row of white blocks on new build #qcx #40m #problem

 

Hi all
Recently completed my qcx 40m.
On power up, the dreaded depressing single top row of blocks.

I have been through all of the troubleshooting hints in 6.3 and every thread I can find.
There also appears to be no crystal activity at 20MHz or 27MHz if my test is correct.
I used my little Sony ICF-SW07 RX tuned into these frequencies and hovered it around the QCX but there was nothing audible.

I also printed out the voltage guide chart and measured the same points using my Fluke DVM.
Both rails (5 and 12) look good and all chips are getting power.
Some are a way off (IC10 p1 10.79v - should be 5.83v)

However the most curious is the display itself, pins 7-14 all at 4.86v.
The backlight and contrast adjustment all working fine.
No smoke, no hot components (AFAIK) and the unit is pulling about 12mA.

I have been over the board countless times looking for bridges and cold joints and now at loss.

Any help or suggestions would be very much appreciated.

73s Ted?
M7ECH
David Seymour
 

Hi,
I had that fault and it turned out to be an un programmed microprocessor. Hans sent me another and all went well.
It seems some entered the supply system. Other people have also had the same.
?Email Hans ?and ask advise.
Dave 2E0EYR


On Tue, Nov 27, 2018 at 8:01 AM <qrp@...> wrote:
Hi all
Recently completed my qcx 40m.
On power up, the dreaded depressing single top row of blocks.

I have been through all of the troubleshooting hints in 6.3 and every thread I can find.
There also appears to be no crystal activity at 20MHz or 27MHz if my test is correct.
I used my little Sony ICF-SW07 RX tuned into these frequencies and hovered it around the QCX but there was nothing audible.

I also printed out the voltage guide chart and measured the same points using my Fluke DVM.
Both rails (5 and 12) look good and all chips are getting power.
Some are a way off (IC10 p1 10.79v - should be 5.83v)

However the most curious is the display itself, pins 7-14 all at 4.86v.
The backlight and contrast adjustment all working fine.
No smoke, no hot components (AFAIK) and the unit is pulling about 12mA.

I have been over the board countless times looking for bridges and cold joints and now at loss.

Any help or suggestions would be very much appreciated.

73s Ted?
M7ECH

 

If you populated the QCX completely, 12mA of current draw is very, very low. You should rather see 120mA. Given that there are no switches in the 12V rail supplying opamps, the idle current of those alone should be tens of mA. I would start by checking the supply part. Even though the 12V rail is not directly responsible for the display and the digital circuitry, it could indicate a related problem.

--
Karlis YL3JG
 

Hi K¨¡rlis
My mistake! I dropped a 0, it should have read 120mA
Thank you
Ted M7ECH
 

Then indeed you could be among the few unfortunate with a blank microcontroller. I had the same issue, and Hans helped me out. If you have an AVR programmer at hand, you can check the FLASH contents to confirm that.

--
Karlis YL3JG
 

Thanks K¨¡rlis

Unfortunately I don't have an AVR programmer.
I have seen other posts about the blank microcontrollers but I feel I should exhaust all other possibilities before disturbing Hans with this.

73s Ted M7ECH

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