Re: Help with 7A18 problem

 

On Sun, Mar 3, 2019 at 06:31 PM, Bill Carns wrote:


The reseating fixed the channel I worked on.
I'm a bit surprised that a well known problem with the removable attenuator modules has not been mentioned here (unless I missed it somewhere). The problem has been mentioned in this group several times and is much more common than bad contact between module and socket:
The pins of the attenuator are fixed to the circuit inside (conductive traces on ceramic substrate) by low-temperature soldering. In a great many cases the quality of the connection is bad, over time leading to contact deterioration.
Removing and reseating the module often causes a very slight movement of the pin inside with the rubbing action temporarily restoring contact between pin and conductive trace on the ceramic substrate.
This leads to the incorrect assumption that the problem has been solved by the rubbing action in the socket whereas the problem will reappear after a while.
Often just repositioning (tilting the module slightly) makes the problem disappear and subsequent repositioning (or time) makes it reappear.
It is quite feasibile to repair the module by opening it (click-locked lid) and resoldering but you need good eyes, dexterity and good tools.

Raymond

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