Introduction and KX1 problems

[Richard Hardy (AQL EMC Ltd.)]

Good morning all,

Firstly a quick note of introduction. I'm Richard Hardy - G7HIP and live in Dorset near the south coast of the UK and have been licensed for 14 or so years with varying levels of activity. The removal of the morse requirement in the UK (my G7 call is a "full" UK licence minus morse) produced the perverse response of making me want to learn morse, mainly so that I can dabble in some home construction and portable operation of really cool, small gear both at home in Dorset and at my alternative QTH in the Scottish highlands as GM7HIP/P.

So that is where the KX1 comes in, as soon as I had found the Elecraft website I knew that the KX1 would be my next project.

But,

I've started the build and it's gone very smoothly, until the testing at the end of part one.

All of the resistance checks etc. are fine and the LED lights !

But nothing else happens, no smoke, nothing getting hot, but no display on the LEDs either,

The board is drawing about 20mA (ish) at 12V on a current limited psu (limited at 100mA or so).

The 6V supply is up and stable and the 5V supply is up and stable, the volts around U3 are OK and some probing with a scope has confirmed that the clock is running (X1, R22, C24, C25) with some more scope probing I can see the rotational pulses from the encoder on pins 3 and 4 of U1, and confirm switch presses from S3, S4 and S5 on the appropriate pins of U1, However here it gets strange, pressing one of those switches grounds the pin of U1, but the line is not pulled high upon switch release it is merely floating up with a few mV of ripple (I assume that the pic output is normally high and pulled down by the 1k's in RP2 when the switches are pressed).

A number of other lines on U1 are at indeterminate levels, pin 2 comes to mind although it was late by then !

As a final test I removed U1 and powered up the board, interestingly it draws a very similar current (although I am only using the last 2 digits of the PSU's internal display so it is not too accurate) and the board behaves in what appears to be an identical fashion. As a final test connecting a jumper between U1 socket pin 20 (+5V) and any of the lines connected to pins 21 to 28 (U1 has been removed !) will cause segments of DS1 (the LED array) to light and turning Z1 at this point changes the pattern of the illuminated segments.

I have double and treble checked the component locations and the soldering, and was working on an anti static workstation so ESD damage is unlikely.

So do you have any ideas ?

I'm wondering what a duff (or unprogrammed U1) would look like, although judging from the quality of my "Elecraft experience", which has been superb from ordering onwards, and the quality of the PCB, components, instructions and packaging so far I doubt that an unprogrammed U1 could slip through the net.

Over to you,

Cheers,

Richard..................G7HIP
 
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