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QCX Rev.4 Help Please

 

Thanks for looking.?

I know next to nothing about electronics but have successfully built 2 QDX and some other small kits.?


Just finished putting together a Rev.4 QCX 5W CW transceiver kit and upon power-up, I get a display with just the top row of text-block showing.?

I realise that this indicates potential issue with IC2, but I have checked the socket and made sure all the chip pins are aligned perfectly and are sitting properly in the socket.?

I have taken all the measurements in the troubleshooting section and present them here in the hope that someone can point me in the right direction.?


PS: I have very carefully checked the PCB for any shorts, poor connections, etc. can¡¯t see anything obviously wrong.?


Thanks for your positive input.?

73, Tom.?
 

Hi Tom. I think the next step is to measure continuity between the LCD pins and the associated pins on IC2.

So look for continuity between:

IC2 Pin ? ? ? ?LCD Pin

2 ? ? ? ? ? ? ? ? ?11
3 ? ? ? ? ? ? ? ? ?12
4 ? ? ? ? ? ? ? ? ?13
5 ? ? ? ? ? ? ? ? ?14
6 ? ? ? ? ? ? ? ? ? ?6
27 ? ? ? ? ? ? ? ? ?4

73 ... Ron

On Mon, May 1, 2023 at 9:04?AM Tom M7MCQ <m7mcqio83ro@...> wrote:

Thanks for looking.?

I know next to nothing about electronics but have successfully built 2 QDX and some other small kits.?


Just finished putting together a Rev.4 QCX 5W CW transceiver kit and upon power-up, I get a display with just the top row of text-block showing.?

I realise that this indicates potential issue with IC2, but I have checked the socket and made sure all the chip pins are aligned perfectly and are sitting properly in the socket.?

I have taken all the measurements in the troubleshooting section and present them here in the hope that someone can point me in the right direction.?


PS: I have very carefully checked the PCB for any shorts, poor connections, etc. can¡¯t see anything obviously wrong.?


Thanks for your positive input.?

73, Tom.?
 

THANK YOU RON - and especially for the clear instructions. Continuity exists between all those ?

Regards, Tom.
 

Forgot to write it on the Troubleshooting Page - Both Clk0 & Clk1 read 0.01V
 

OK. That's a problem. I thought you were getting 1.6 volts on CLK0 and CLK1. If there are no clock signals and there is no activity on the display, then it looks like trouble with? IC2, the microcontroller. Look for 5 volts on pins 7 and 20. If not there, follow the schematic and find out why ... maybe an open inductor. If voltage is there, then the IC may be bad and you will have to plug in a substitute. If you have a spare or even another QCX, mini or plus, the IC2 chips are all interchangeable.... Good luck . .Ron


On Mon, May 1, 2023 at 11:30?AM Tom M7MCQ <m7mcqio83ro@...> wrote:
Forgot to write it on the Troubleshooting Page - Both Clk0 & Clk1 read 0.01V

 

Darn!! There¡¯s 0V on pin 7 and 2.44V on pin 20 ?

I searched Amazon.co.U.K. For an ATmega328P but a few come up and I don¡¯t want to get the wrong one ??¡á?

This kit only cost me ?10 at a rally - although i don¡¯t like quitting (or wasting two days of my time), it might be better to admit defeat.?

Thanks for trying Ron - much appreciated.

Regards, Tom.
 

Don't give up yet Tom. Check L5 and L6 for continuity. I'm thinking one of them is open. They feed the 5v to pins 7 and 20.?

Ron

On Mon, May 1, 2023 at 12:12?PM Tom M7MCQ <m7mcqio83ro@...> wrote:
Darn!! There¡¯s 0V on pin 7 and 2.44V on pin 20 ?

I searched Amazon.co.U.K. For an ATmega328P but a few come up and I don¡¯t want to get the wrong one ??¡á?

This kit only cost me ?10 at a rally - although i don¡¯t like quitting (or wasting two days of my time), it might be better to admit defeat.?

Thanks for trying Ron - much appreciated.

Regards, Tom.
 

I don¡¯t want to give up , but I don¡¯t want to be a PITA to other people either.

L5 & L6 both have continuity Ron.

Thanks, Tom.
 

You don't have to worry about being a PITA on this forum Tom, we are all delighted to help.?
Did you say you already have a another QCX?
If not, I am in the Newmarket UK area and can easily check your ATmega328P on one of my radios.
Then at least you will have eliminated one element of the puzzle.

73s Ted
2E0THH
 

Tom,
Remove IC2 and then check the voltages at pins 7 and 20. If they are good with IC2 out, but not there with IC2 in, then suspect a bad IC2, otherwise check back to find out where the voltage is missing.

73
--
David Thomas M0OOR
 

Absolutely DON'T give up on it Tom. I had great service from one of these and put it through absolute torture for years running WSPR. I finally blew up several chips by shorting one of the output transistors (drain and gate I think from memory) while trying to measure the powered up voltage on one of the drains. This put about 12v onto the driver chip, and cascaded the disaster onto probably the si5351 which put it beyond repair for me, because I can hardly see the surface mount chip let alone remove and replace it. Your problem is likely much simpler. I loved that little radio and its hardy performance, it certainly put up with some abuse from me. I spent a very pleasant evening on one Christmas Eve building it, and to my surprise, because i have less than great close vision nowadays, it was up and running on WSPR before Santa came down the chimney. I hope you can fix yours. Mine had many changes of output fets caused by the two minute hell of WSPR to those tiny plastic fets and my flaky full wave loop antenna going out of tune. I lost count of how many times I replaced them. In the end, the traces were gone off the board and I had to make an off the board PA for it. Keep asking and seeking the fault. I think you'll soon have it running.
 

You are all VERY kind and helpful - THANK YOU!

I now have (don¡¯t ask me why) ?4.87V at Pins 7 & 20 ??? I haven¡¯t reheated any joints or anything ??¡á?

The bottom row of the screen is still blank.

Clk0 & Clk1 still read 0.01V by the way.
 

Hi Tom
Just curious if you managed to get your radio on the air, I hope so.
73s Ted
2E0THH

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