SDS100: Cold Solder Joint

Mike445

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The symptoms were nearly identical to before, except instead of getting no RSSI reading while a transmission, I was sometimes getting -40dBm, which is unusually strong. Everything else was the same; super slow scanning, pulsing static on multiple channels, etc. Not relishing the thought of spending another month without the scanner, I opened it up to see what Uniden had done, in the hope that it might yield a clue to the problem. And I found something I'd missed previously:

The third pin from the right seems to be the culprit. The solder connections on either side have touched up by hand, but the third one hasn't, and if you compare it to the machine soldered pins on the left, it has conspicuously less solder than all the others. After reworking that joint so it matches the others, the radio works properly again. Missing that dry joint is clearly a fail on Uniden's part.

The other thing I did was shimmed the SMA connector on rear circuit board so it isn't putting lateral stress on the connector. With the front circuit board screwed down lightly, there was a ~0.2mm gap between the inner SMA connector retainer and the case, and when tightening the outer SMA retainer, the rear board was pulled upward relative to the front board, which pulled sideways on the J401 connector.


To solve the problem, I 3D printed a spacer that was 0.2mm thicker than the inner retainer, and installed it so that after tightening down the outer SMA retainer, the two halves of J401 are correctly aligned, and there is no lateral force on it.
I'm having all the same issues (no RSSI, pulse static, etc.... They just started. I also notice when I wiggle the antenna I can get the transmissions to start flooding in. I'm interested in getting the GPS md as well as the cold solder fix and perhaps you can sturdy up my antenna port as well? I currently use one of your SMA/BNC adapters and its never come off since the day I got it. I sent you an email on your website.
Mike Cira
 

buddrousa

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From what I see the RSSI dropping out and it still receiving is the prime symptom of the COLD SOLDER JOINT.
Nice video I wish more would use these as it gives the full picture.
 

Ubbe

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From what I see the RSSI dropping out and it still receiving is the prime symptom of the COLD SOLDER JOINT.
It looks to be just the antenna connector that needs to be resoldered on the circuit board. Cold solder joint in the J401 connector shouldn't behave like that when you are stationary on a channel?

/Ubbe
 

buddrousa

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Ubbe Jon has done shown the board the antenna is mounted to is the board with the cold solder joints as posted in this very thread..
 

jonwienke

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The antenna joint failing won't cause pulsing static. If J401 has bad joints, pushing on tbe antenna could affect how they connect. I'll post my findings when I get the radio open.
 

Mike445

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The antenna joint failing won't cause pulsing static. If J401 has bad joints, pushing on tbe antenna could affect how they connect. I'll post my findings when I get the radio open.
I sure do get pulsing static. Not all the time but it does happen. Thank you Jon!
Mike C.
 

jonwienke

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Having less than fun today. The unit I'm working has oxidation on the underside of the pins, and consequently they really don't want to stick properly even when bathed in flux. I tried wicking out the old solder and restarting with new, that isn't working either. Trying to figure out a solution short of completely removing the connector, scraping the pins, and starting fresh. Getting it aligned properly is a concern, there don't seem to be any indexing pins. It's clearly placed in position by a robot during manufacturing. :(
 

spywiz

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Having less than fun today. The unit I'm working has oxidation on the underside of the pins, and consequently they really don't want to stick properly even when bathed in flux. I tried wicking out the old solder and restarting with new, that isn't working either. Trying to figure out a solution short of completely removing the connector, scraping the pins, and starting fresh. Getting it aligned properly is a concern, there don't seem to be any indexing pins. It's clearly placed in position by a robot during manufacturing. :(
Hopefully not mine! Being it is less than a month old. Dang, I hate being without it!!
 

jonwienke

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Just as an FYI, I've been dealing with this for the last couple days:

20201015_214034_HDR.jpg

So unfortunately I haven't been able to get much soldering work done; I've been moving stuff and spraying and getting ready to bomb the house.

It's hard to concentrate on resoldering tiny solder joints when you're getting swarmed and bitten by boodsucking vermin.
 
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