EFMini build - went south on step one...

Doh and double Doh!

My EFMini kit arrived today...

I’ve prepared the tools, printed the instructions, read them twice... got over my nervousness and started in slowly and carefully...

I soldered the resistor legs to guide the GPS chip in, and as I slid the GPS module down into place, one of the guiding resistor legs popped off and took the channel conductor with it.




My operating diagnosis is I over heated the pads cleaning up a *very* small solder overflow with desoldering braid on the GPS pad. I was so worried about it being solder free, perhaps the cure ended up being worse than the disease...

While trying to diagnose why the GPS didn’t quite fit (the tolerances are TINY) I slid the GPS back into place and promptly popped the other pin out on the same side, it also took the channel conductive material with it...



Double Doh!

As for why the GPS didn’t fit I’m still not sure - the joints were about as clean as I could imagine them being... still scratching my head on that one...

So I’ve taken pictures and emailed @cerving. We will patiently await to see what he suggests.

I did order two EFMini kits, so I can resume the build with the circuit board from the other kit if @cerving’s diagnosis is “dead-on-user-error” while I patiently wait for a newly purchased replacement part...

Ummmmm, Wait and see what he says. Some of the GPS contacts aren't used for anything. If that contact serves no purpose, you might be fine.
I was able to salvage a couple of regular v1 boards with outboard GPS chipsets. Takes one wire to one pad and that's it. I used the 3.3V terminal on the
aft end of the v1 EF to supply power to the GPS. You might not be in hot water. Kurt

ksaves2 said:

Ummmmm, Wait and see what he says. Some of the GPS contacts aren't used for anything. If that contact serves no purpose, you might be fine.
I was able to salvage a couple of regular v1 boards with outboard GPS chipsets. Takes one wire to one pad and that's it. I used the 3.3V terminal on the
aft end of the v1 EF to supply power to the GPS. You might not be in hot water. Kurt

Click to expand...

Waiting patiently - That is the plan..

I am still wondering why the channel popped out... Looking at the board, there doesn't seem to be the typical evidence of overheating I would expect - there is no blackening of the surrounds like I have experienced in the past when I have overheated a pad on a kit... If I didn't overheat it, the only other cause I could think of is mechanical stress - If it was mechanical, I am double stumped, as I can't imagine the pins being any better aligned than I had it..

Stumped... 🤔

I only used two legs because of how tight the fit was. Worked great. As for having pulled the traces off, I believe there's a fix for that.

Tonimus said:

I only used two legs because of how tight the fit was. Worked great. As for having pulled the traces off, I believe there's a fix for that.

Click to expand...

I was looking at it again tonight - I think I can manage with the two that are left if I tilt the board back at 45° (with the gps unit taped down) while I solder it.

Also, I’m thinking I might be able to actually use the resistor legs to replace the traces...

Looks quite salvageable to me. I would place the guide back into position and get a good glob of solder on the brass conductors on the top and bottom.

Those corner pads don't connect to anything... that was by design, in case this happens. Go ahead and solder,you should be fine. Yes, it is a bit delicate... I might make the board about .050" wider the next time out to help make it a little easier.

I had the same problem with the board being a touch too small. I ended up lining everything up and then taping the gps to the board and doing one solder on each side of the module. Took a little bit of time to get the alignment but it worked.


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On @Cerving's advice I pressed on regardless.. Unit is now soldered up.. Initial tests left me at the "flashing red LED but no orange LED" stage..

I am testing with a 9V (need to get a JST pigtail) so it's now in the back yard... time will tell..

I've taken macro pics (iPhone + 10x Jewellers loupe) as I went.. If this works (or even if @cerving needs to help me troubleshoot it) I have high res pics!

I had the same issue on my first EFMini. I was able the bridge with solder with a little work. The tolerance on the width is very tight...as in Chris made it right on the nuts!

After the first power up, it did take many minutes with a clear view of the sky to get a GPS fix and the orange LED. I bet you are in good shape.


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After no signal transmitting after 30+ minutes outside, I took to the unit with the loupe... I reflowed the solder on one of the GPS pins that looked cold at the GPS end (shiny in the track, dull looking on the GPS end) - re-tested with the unit outside - checked it after 15mins and it was working.. (well, orange light flashing..) w00t!

And.... VICTORY...

I got the eggfinder LCD built tonight (still have to cut/drill the case and mount it) but ICANHAZ GPS!

This is a great product!

@cerving: as an FYI, both the TX and RX were set to 915MHz out of the box - I reprogrammed them to 923, and I note that when reprogramming it, it did restrict me to AU permitted ranges, but it was all running at 915 to start - is this intentional for the AU version?

The transmitter/receiver pair had 921 written on the bags..


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snrkl said:

And.... VICTORY...

I got the eggfinder LCD built tonight (still have to cut/drill the case and mount it) but ICANHAZ GPS!

This is a great product!

@cerving: as an FYI, both the TX and RX were set to 915MHz out of the box - I reprogrammed them to 923, and I note that when reprogramming it, it did restrict me to AU permitted ranges, but it was all running at 915 to start - is this intentional for the AU version?

The transmitter/receiver pair had 921 written on the bags..


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Click to expand...

The modules are on 921 and the AUS firmware should see that the LCD hasn't been frequency-programmed yet so it show the default (921). Displaying 915 may be a bug, but the modules are on 921 so you weren't out of compliance... I'll look at the display issue.

One happy camper there. Kurt

cerving said:

The modules are on 921 and the AUS firmware should see that the LCD hasn't been frequency-programmed yet so it show the default (921). Displaying 915 may be a bug, but the modules are on 921 so you weren't out of compliance... I'll look at the display issue.

Click to expand...

Awesome - glad to know... the last thing I need is the ACMA goon squad driving around triangulating me...

I had a similar issue with the half PTH barrel popping out during assembly. I was to a pad that wasn't connected so I was not concerned and continued successful assembly.

I think it is because if the wires are soldered off-center on the carrier they don't leave enough space between them for the GPS module to go in easily. It might be mitigated by moving the rows of holes on the main PCB a little wider (maybe 5-10 mil or thereabouts).

Awesome - glad to know... the last thing I need is the ACMA goon squad driving around triangulating me...

Click to expand...

They don't need to triangulate. They just decode the packet.

@cerving - question: what’s the holes labelled “SW” above the button on the LCD used(usable?) for?


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snrkl said:

@cerving - question: what’s the holes labelled “SW” above the button on the LCD used(usable?) for?


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Click to expand...

They're for connecting an external push button, which is highly recommended (and required if you're using it with an Eggtimer TRS).

cerving said:

Those corner pads don't connect to anything... that was by design, in case this happens. Go ahead and solder,you should be fine. Yes, it is a bit delicate... I might make the board about .050" wider the next time out to help make it a little easier.

Click to expand...

Chris,
This solder/unsolder corner guide pins ballet may be an overkill, especially given the regular TX C1 instructions to tape the GPS pad down with masking tape.
Any reason for retiring masking tape trick during TX mini assembly?
I realize real estate is tighter on TX Mini board, but you only need two (2) solder joints on diagonally opposite ends of the GPS pad to secure it in place, and the rest of the joints could be soldered from there. This seams easier than soldering resistor legs as guide, and possibly safer if the legs tend to pull channel conductors off during subsequent removal.
:confused2:

a

cerving said:

They're for connecting an external push button, which is highly recommended (and required if you're using it with an Eggtimer TRS).

Click to expand...

Perfect- that’s what I was hoping you’d say. Now I have my case assembled and looked at it in earnest, I was not looking forward to having to unscrew it in the field to retrieve last coordinates!

afadeev said:

Chris,
This solder/unsolder corner guide pins ballet may be an overkill, especially given the regular TX C1 instructions to tape the GPS pad down with masking tape.
Any reason for retiring masking tape trick during TX mini assembly?
I realize real estate is tighter on TX Mini board, but you only need two (2) solder joints on diagonally opposite ends of the GPS pad to secure it in place, and the rest of the joints could be soldered from there. This seams easier than soldering resistor legs as guide, and possibly safer if the legs tend to pull channel conductors off during subsequent removal.
:confused2:

a

Click to expand...

I'll look at doing it with two diagonal pins, with some tape. Taping the GPS module alone doesn't work as well for the Mini because you're soldering the pins on the side, instead of the top. I tried and abandoned it early on... I felt it was asking for a little too much precision in soldering.

cerving said:

I'll look at doing it with two diagonal pins, with some tape. Taping the GPS module alone doesn't work as well for the Mini because you're soldering the pins on the side, instead of the top. I tried and abandoned it early on... I felt it was asking for a little too much precision in soldering.

Click to expand...

FWIW: with my build, I used two pins on one side only (that was all I had left!) and tape - I soldered the unpinned side first with the GPS unit essentially resting on the two pins on the other side while being taped down - it worked pretty well - I will likely build my second EFMini the same way...

@cerving: are the plethora of macro pics I took useful to you for documentation? If you thought they would be helpful I am happy to provide them. I would also be happy to add them to the instructions document as a way of saying thanks for awesome support, given your time constraints with 'real jobs' etc..