[UK-CONTEST] K3 working again

[Ian White GM3SEK]

Chris G3SJJ wrote:
>Firstly thanks for all the comments and suggestions. Here is the story 
>for any other K3 owners who experience the problem. Initially I was 
>hesitant to accept that the fault might be a poor contact on a 
>connector pin, however I called in at the local Maplin store and bought 
>a £3.50 can contact cleaner. Spread the ESD mat out and wired myself up 
>to it! Removed both KSYNC3 boards and the KREF3 board, examined the 
>surface mount soldering carefully and then sprayed the pins on the PCB 
>connectors.
>
>On re-assembly the fault was still there! That is, no rx /tx and PLL1 & 
>2 display showing either 7.4 or 0.0. By chance I happened to tap the 
>TXCO, which is the metal can component on the KREF3 board, and the 
>fault cleared. The pins were quite sloppy in the DIL carrier so I bent 
>them very slightly to make a more solid fit. I have had the radio on 
>soak test now for several hours now and it is very stable.
>

I had exactly the same problem about a year ago. The wire leads on the 
oscillator module are too thin to give a completely reliable contact in 
the DIL socket, so in a few unlucky cases it eventually loses contact 
and throws up an ERR PLL.

Bending the pins was not a complete solution here, as the fault came 
back after a few weeks. What finally did the trick was tinning the wires 
with solder to make them just a tiny bit thicker. The pins went into the 
socket with a much more solid feel and there have been no further 
problems.

Related to that, the oscillator module was retained in the DIL socket by 
a single wrap-around cable tie. The nylon tie provided in the kit was 
too stiff and was causing one end of the module to tilt out of the 
socket. It is better to use two very thin ties of a softer material, 
inserted under the DIL socket from opposite ends so the module is pulled 
down flat.

>
>A tip - Instead of trying to get the scope probe down the TMP mini coax 
>sockets, I used a spare patch lead supplied with the 2nd rx kit. 
>Plugged one
>end into the socket and clipped the probe on to the other end.
>
Long medical forceps are a godsend for handling those TMP plugs deep 
down inside.

>A satisfactory conclusion all round!
>
Fingers crossed for you, Chris.  If it happens again here, that DIL 
socket has already had its final warning.



-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek