I agree BJ
I only throw away switches if they are destroyed
I have a couple 4x1 diseqc's that port 4 is shot...but 1-3 work fine
I still have my first diseqc switch around here somewhere. Similar to yours, but 1, 2 and 4 work, and port 3 took a crap!
This is a very interesting discussion. I, like B.J., do not toss my suspected bad switches. Why I keep them is kind of an unknown to even myself. But, allow me to explain something that I have personally observed and see if it rings any bells with all of you.
First of all, I haven't been utilizing the four port DiSEqC switches much in the past few years as I have set up my motorized dish and the application of a switch was no longer a necessity for me. But, going back in time a little bit, I had a number of fixed point dishes which were combined using an array of SW21 and 4X1 DiSEqC switches.
During that time, I found several of the 4X1 DiSEqCs to fail on me. Sometimes, as B.J. mentioned, they were defective right out of the box! Other times, they seemed to work decently initially, but after a few weeks or a couple of months, problems started to appear.
Port #4 seemed to always be the first to fail. Sometimes it would just seem to die a quick and obvious death and at other times, it would simply slowly degrade. The signal strength and quality level would diminish gradually over time until it would finally become unusable. If I continued to use the switch "as is" then I would notice that port #3 would follow the same path of demise as port #4 did.
I never continued to use the switch after these two ports failed, so I don't know if port #2 would follow suit in numerical order.
I may just be trying to look for an electronic conspiracy theory here, but maybe there is something else to it. I just cannot explain why so many different 4X1 DiSEqC switches failed in the same pattern for me. Perhaps you guys have witnessed this, too?
I need to mention that all my switches were protected from direct exposure to the elements, but were still outside (in a Hoffman box with a gasket seal). Therefore, no direct rain or sunlight or intense heat was at hand, but still, it was not like being inside in a controlled environment.
As I mentioned, maybe I am looking for some "conspiracy" theory here and I am using that term as a tongue-in-cheek comment, but from what I have read of your comments compared to my own experiences, there appears to be a pattern here.
From B.J.'s comments, I get an impression that the switches which are failing are exhibiting an almost uncanny resemblance to the operation of a FET. I mean in the sense that, over time, the gate control voltage seems to become residually controlling and diminishing the current capacity of the junction until it eventually no longer can maintain the connectivity between the source and the drain.
I am certain that this is not a valid explanation of the problem, but the symptoms seem to want to act as if it were so. Hence, the ability for the switches to be resurected after time passed. It sounds like a capacitive charge is building up on the gate that is preventing the channel from opening fully and grows increasingly worse. Then, after taking the switch out of service for a length of time, that charge bleeds away and the switch acts like it was new once again.
As far as I have been informed, most of these switches are constructed with PIN diode junctions and therefore my theory doesn't really follow the guidelines of the operation of these junctions exactly. I cannot explain why these switches are reacting this way. However, I think that you can identify with how I perceive the symptoms.
Again, I don't intend to say that I am able to explain the reasons why, I just know that it is occuring and what it seems to emulate on the surface or what it appears to be at first glance seems to have a certain pattern and therefore it should be explainable.
I say that this is a very interesting subject as you all seem to have noticed many of the same things that I have also observed.
RADAR