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Eggfinder GPS missing satellites

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Voyager1

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That's helpful. Those of us new to this soldering business need this type of advice. Is there a preferred cleaning paster that should be used?

Yeah, but the instructions say that extra flux shouldn't be needed and might result in an adverse result. For those of us that aren't soldering experts we don't know when to break away from the instructions and do something different. Curious, why is there residual grease on the PCB if it has been cleaned per the first paragraph?

This I already do...
The cleaning paste I use for PCBs is called "Jiff" here. It's a gentle abrasive paste used in kitchens & bathrooms. Only apply and rub lightly with a moist paper towel. Don't scrub it! Wash, rinse and dry well after.

If you are new to soldering, then follow Cris' instructions - period! However, as I've been involved in electronics and soldering for 45 years, I can make up my own rules! There is always the possibility that you might touch the PCB pads after the cleaning, so there might be some residual grease from that. Also, if you didn't wash the board sufficiently and left some contaminants on the pads, the boiling flux helps to remove this.
 

OverTheTop

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For lightly oxidised PCB pads a scrub with a piece of paper towel works. For heavier oxidisation I would use something like a fine scotchbrite pad to gently remove the film. I don't like the idea of steel wool after a board is assembled as a fine piece can get where it will cause problems. I am also personally not very at ease with using a cleaning paste.

An alternative would be to use a microscrub contact cleaner. These are normally used for polishing up relay and switch contacts after any lumpy bits have been removed with a diamond file. They are slightly abrasive and not likely to harm other parts around. I have these in my toolbox at all times as they have 1001 uses!
They are just a flexible substrate with some very slightly abrasive surface. Here is an example.
 

DeepOvertone

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The pink eraser on the back of a pencil is actually really good for cleaning mildly oxidized pads. It contains a mild abrasive and sloughs off as you go so the contamination rolls away. Be sure to still clean up with alcohol afterwards.
 

OverTheTop

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The pink eraser on the back of a pencil is actually really good for cleaning mildly oxidized pads.
Now there's a blast from the past. I had forgotten about that one. Used to do it all the time on my Trash 80 (Tandy TRS-80) computer back in the late 70's. Works well.
 

steveh.jae

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The pink eraser on the back of a pencil is actually really good for cleaning mildly oxidized pads. It contains a mild abrasive and sloughs off as you go so the contamination rolls away. Be sure to still clean up with alcohol afterwards.
It’s what we used as PME techs years ago
 

cerving

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So I just threw a TX transmitter together, pre-tinning the ground pads on the GPS module. It seems to work fine, pre-tinning the pads doesn't seem to make it any easier to get the solder in the slots (we recommend that you turn up the temperature 20F or use a slightly larger tip), however I think it's probably going to make it easier to get a good bond on the GPS' ground pads. I'll revise the assembly instructions on the GPS transmitters.
 

Swany

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I recently completed my Eggfinder Mini and I think I have the same issue. I can get a GPS fix, but only intermittently and only after several minutes (like 10-15 mins, even outside). My GPS module had the small ground pad holes on the back even though I bought it last summer, so it seems like there were still older modules/boards still being sold as recently as last August. Is there any way to get the TX module off the mini and re-solder the ground pads or should I write this one off ?
 
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n27sb

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I have done it before.
I heated up the two pads next to the antenna and sucked up most of the solder with wick.
Slide a razor under the board and heat the pads again. Slide the razor underneath that area to slightly separate.

Run your iron back and forth on the pads on the other side to heat all pads.
Gently lift the board as the solder melts.
If you go too fast you will lift the copper pads.

Or, use a hot air rework tool to heat the whole board.

Either way it is tough to do.

Only try it if the unit is trash anyway.
It takes advanced skills to be successful.

Good luck
 

cerving

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You can get the GPS module off by using desoldering wick to remove as much solder as you can from the pads and hopefully the holes, turn it upside down, and stick a hot air rework tool into the big center hole and patiently wait for the board to get hot enough to let go of the GPS' solder. When it gets there, the GPS module will fall off. Consider this a destructive process for the GPS module. You may have to clean up the PC board pads with some desoldering wick; I've seen pads lift off of the GPS module themselves and stick to the PC board's pads.
 

Swany

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You can get the GPS module off by using desoldering wick to remove as much solder as you can from the pads and hopefully the holes, turn it upside down, and stick a hot air rework tool into the big center hole and patiently wait for the board to get hot enough to let go of the GPS' solder. When it gets there, the GPS module will fall off. Consider this a destructive process for the GPS module. You may have to clean up the PC board pads with some desoldering wick; I've seen pads lift off of the GPS module themselves and stick to the PC board's pads.
Thanks for the advice, Chris. Although I’m a little confused as to why I would need to remove the GPS module as well. My thought was to remove the TX board and try to reflow the solder in the holes on the back side of the GPS module to get better contact with the ground pads without removing the GPS module. Also, did you get a chance to look at the photos I sent you last week to see if there is anything else I might have screwed up that I should fix first before I embark on this major surgery. Thanks !

Mike
 

cerving

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I'm not advocating removing the GPS module... unless you have one that got dorked due to a short and/or reverse polarity connection. Removing it is essentially a destructive process.

If you have a newer transmitter with the ground "slots" you can improve the connection by LIGHTLY pre-tinning those eight ground pads on the bottom of the GPS module before you mount it.
 

Wayco

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Had a big rocket land hard a couple of weeks ago, and it tore off the GPS module on my EF TX circuit board, despite the epoxy holding it on. Only two of the ground plane pads were attached, and most of the pads on the GPS module were pulled off when it separated.

EF GPS 2.jpg


I contacted Cris this morning and he is sending me a replacement GPS module. I cleaned up the circuit board and will attempt to install the replacement. I'm gonna try the tin before you install method, standby for more pic's when I get the part.
I'm not very good at soldering, as you can tell from that picture, so wish me luck on the repair.
Just got tracking info. from USPS, coming priority mail! You just can't beat Eggtimer customer service!
 

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