The real issue starts with the bare PC board not being adequately cleaned after
the etching process. And most were if all were not plated. Thus some of the
etch chemicals remained. The boards were populated and soldered. This left some
off the acid etch chemical under the solder to do its nasty chemical work for
years. Solder “touch-up” will correct some issues for a period of time but
the gremlin remains to only appear later in time.
The only correct and long term solution I have found is to fully depopulate the
board, clean it to bare bright copper, fully tin the board with silver bearing
solder and repopulate the board. THAT IS A LOT OF WORK. And one must be
very careful with the parts removal and installation process as some parts are
no longer available. For these reasons, I long ago stopped repairing the
original Paragon radios.
73
Bob, K4TAX
Sent from my iPhone
> On Jan 31, 2020, at 8:30 AM, Pete Ferrand <petef@sprynet.com> wrote:
>
> Not all the pc boards, just replace the solder on the major and minor loop
> boards. Did that to mine ten years ago and it worked perfectly ever since.
>
> Pete
> WB2QLL
>
>
>
>
>> An update on the Paragon 585, now have full TX, by total re-solder of the
>> 2nd mixer board, but its not all good news, I set the frequency at 7.050mHz
>> and my counter shows a frequency of 4.300mHz, a difference of 2.75mHz, ah
>> says I to myself I have seen that frequency on the minor loop board terminal
>> 87.
>> I replaced U5 (mc1496p), still no joy, checked the output from U4 onto pin4
>> of U5, seems ok, checked continuity on T2, that was ok.
>> Stumped but some success.
>> Any pointers now please, I suspect that I will end up doing a total
>> re-solder of all of the remaining PCB,s, but as I am retired on my own I
>> have the time.
>> 73
>> Snowy G0HZE
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