From my experience and recall, it was generally limited to the PLL
boards, minor loop and major loop boards. As to the others, usually
connector contact failure was the next common cause of failure. This is
resolved by cleaning and exercising the connectors. Never spray
anything into the radio.
73
Bob, K4TAX
On 1/31/2020 1:03 PM, ROLAND HOWELL via TenTec wrote:
Thanks for the advice Pete and Bob
As you say Bob, that's a lot of work on the PCB,s, did all the boards suffer
from the residue from the etching process?, I only ask as I still have no RX,
will attempt to inject a frequency along the RX path tomorrow, I have replaced
the 74ls90 ic on the minor loop board as I appear to be missing my 2-2.75mHz
output, didn't make a difference.
Onwards and upwards
73
Snowy G0HZE
On Friday, 31 January 2020, 14:48:47 GMT, Bob McGraw K4TAX
<rmcgraw@blomand.net> wrote:
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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