Hi John
Just had a closer look at your pic of 2 boards, in particular the damaged one.
It appears from the pic that the pads have not come away from the board but the solder joint has let go. It appears not to have been soldered properly underneath and just had a sort of “token” joint along the edges. Not very substantial but in this case possibly a good thing as the board does not appear to be damaged like lifted tracks.This could be a by-product of flow soldering during mass production caused by the connector body not getting hot enough. Re-enforces my statement above re using an iron with enough capability to overcome the heat sinking effect of the connector mass.
Have a close look to see if the gold has let go at all. The gold may not have been removed prior to soldering. I will add here that with extremely thin plating as found on a lot of domestic products the action of tinning once and soldering is usually sufficient to do this job. Strangely it is higher end products that require the extra effort when carrying out soldering operations.
Also if replacing be careful to get the correct centre tab in the correct orientation. Only one of these smaller tabs is the centre pin, the other one is connector body or ground. Reversing these will put a short on the centre contact to ground. Refer data sheet on Core web site which shows a notch in the body to identify orientation.
Cheers Bob
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It’s odd, but the boards look dirty in that pic, but to the naked eye they’re quite clean.
Here’s a better photo of the damaged connection.
That long scratch is mine. I was pressing the pigtail plug onto the receptacle with the point of a blade and it slipped. Another lesson about the right tool for the job. I think it was still working after that mishap so I don’t think those two tracks were cut.
Where exactly?
My iron is 25-30W. It’s basic but serves me well. After lockdown I can access a Hakko soldering station and a host of tools to help with this repair. I don’t want to damage these boards but it does lead to interesting learnings. I’ll be well pleased if I can rescue this GPS unit.
Interesting that you suspect the integrity of the original soldering. I wonder if that could be one reason why a board doesn’t produce sat data from the get go. That could be the first thing to test with a non-performing unit.
John.
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Hi John
I don’t think that iron will be up to it. I personally would not use it for that job, wait for the Hakko.
I questioned this as the body of the connector has come away cleanly leaving a distinct outline of the connector tab in the remaining solder without attempting to lift any of the track… On the other hand the centre pin tab does appear to have lifted the track. It is a bit hard to make out exactly but this smaller tab looks to have been soldered better and held enough to damage the track. This tab being smaller has far less mass and would not heatsink the solder operation any where near as much.
If the track has lifted and is still in good condition IT CAN BE REPAIRED provided is just a surface mount pad and not a plated through hole as a via. You have to make sure the rear of the track and board are thoroughly clean. Be careful to not break the track. You will need 2 part Araldite. Use a tiny amount to re-glue the track down. Use something to hold it down while the Araldite cures. Araldite is required (not superglue) as it has to withstand soldering temperatures. You will have to inspect that centre pin track and determine what has happened as it is very hard to be certain from the photo.
This is a valid repair and was sometimes used by the production line girls of my previous employer. They were very good at it and even could replace bits of broken track and pads on single sided or 2 sided boards and you would not pick it unless you knew where to look. There were even tiny rivets available to repair damaged vias in double sided boards. Multi layer boards (more than 2) of course were pretty impossible.
Cheers Bob
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The solder blobs for the outer wire of the coax are both still fully attached to the board. I see what you mean – the solder joint was weaker than the adhesive joint with the board. The pin is well attached to the track which is mostly still in place on the board all the way back to a pin at the Neo. There is no via for the centre pin:
Yes, I’ll leave this job till I get back to the maker space where there’s a great workbench and tools. I’ll ask them to get a USB microscope. Repairing boards would interest others.
Here’s the microscope I’m using:
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Bob,
I followed yr tip and read up on high reliability soldering. Impressive what can be done.
I also found some videos on repairing RF connectors - there’s some good info out there.
Here Richard is ditching the uFL connector altogether and has made a “wee fork” from the pigtail. I didn’t think I could strip such a fine wire, but this encourages me to have a go:
repairing RF connection
But this video about maintaining the reliability of a uFL connection is by a pro. He confirms much of what I’ve learned thru my stumblings. This is must-see for anyone using the type of GPS board we’ve been discussing:
uFL reliability
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Thanks James.
I do have a unit with integral antenna.
I like this board. They are low-cost, very popular and work. Now I know where the vulnerabilities are regarding the antenna I’m confident I can mange them and avoid losing more units.
The video I posted in my previous post about maintaining reliability of the uFL connection is something I could have profited from months ago.
John.
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Hi John
I think this connection (antenna) is probably meant to be made when the unit is first purchased and put into service and never touched again. With this sort of scenario it might last for almost ever…
Without much care and with constant use they would be very much prone to failure. Although much more expensive I think the SMA screw up style of connector is more robust as they are used sometimes on test equipment where your test leads nearly have to be beyond suspicion or you are wasting your time.
Cheers Bob
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I think I see why I haven’t damaged any GPS units yet. I only buy ones with an SMA connection.
I have been trialling GPS reception indoors. I have an antenna resting on a window ledge (inside) of a ground floor room in a two storey house. The house next door is less than a meter away so the sky view is a narrow strip between the two houses. Takes a while to get a fix but it works.
I have found it very useful to connect the GPS module to a TTL/USB adapter and then send the signal to VisualGPS, Gives satellites in view, signal strength, sky view, and collects some stats over time to assess the quality of the signal (poor but usable). The GPS to adapter connection is just 5V TX to RX and GND, The 5V available on the adapter will power the module.
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The IPEX documentation says it is meant to be a permanent connection. They rate it for 30x mating cycles. The pro in the video above says that when the connection loses its snappiness and the pigtail feels loose it’s time to replace the pigtail. So, yeah, I think it shud be immediately installed and treated as a permanent fixture.
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Alan,
I’m satisfied that my problems arise from the extensive handling I put the units through. Using SMA connections and having them fixed in one place would alleviate that effect.
For what I’m doing I have to handle them but I’m aiming to get them installed in a project box asap. There’s always other components to put into a project like Bluetooth, display, switches, Arduino… and that leads to a lot of manipulation. I just have to take proper precautions. I think shorting the antenna when inserting it with power on is possibly the main culprit. As far as I can tell this kills the antenna, not the GPS, but not sure.
I agree. A fix indoors is possible. I think if you get a fix outdoors first and bring it indoors it continues to have a fix, whereas to start from cold indoors it takes longer. The important thing I want others to recognise is that an obscured view of the sky is not the explanation of a complete sat data blackout which many users report. So people waste effort trying for a perfect skyview when the real problem is the GPS just isn’t getting any sat signals at all, in which case the quality of the skyview is irrelevant.
I haven’t used VisualGPS. I use u-center and my own app. I’ll take a look at VisualGPS, ta.
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Hi John
One hell of a learning curve. But I think very educational in the long run.
Cheers and good luck with your ongoing projects.
Bob
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