Eggtimer TX

[downhill_D]

Hello!
I just built two Eggtimer TX's yesterday and today. The first 1 bench tested great the Hope module led flashed and acquired satellites (amber led). The second one the Hope module flashes the two leds (green and red) at once and then goes out. For those with experience where did I go wrong on the second TX build? I have successfully built an egg timer classic, a wifi switch and tx transmitters to date. Very little experience soldering but I have a nice digital solder station to help me get things right. This was my first kit fail so I want to know if I can fix it and how I did it.

 

[Voyager1]

The TX's Hope module will typically flash both LEDs on power up. If all is OK, then the red LED will flash regularly as the GPS module sends data to the Hope module. The fact that there is no further activity suggests a connection issue on the board. The likely culprit is the GPS module. I would be closely checking ALL solder joints and re-flowing any that look dull or crystalline. Also check the GPS module grounding. Cris will no doubt chime in here and suggest what should be done.

 

[Tractionengines]

Can you post photos of the assembly. (Both sides, close-up, and in focus ) may help us spot something.

Since 1 is working and 1 isn't. I would be looking for a cold solder joint, or a solder bridge. Start with careful inspection of GPS module.

 

[downhill_D]

I will double check the grounding on the gps. I had issues during fill with the solder tip and switched part way through. If still having issues will post a picture of the assembly-I rechecked all top side gps connections very well. I'm guessing you are right-the grounding of the chipset might be it. I appreciate the quick input, I will double check the grounding fill with a better tip.

 

[downhill_D]

I re-melted the grounding channels and still same result. The lights flash and then no blinking red light. I will have to come back to this and re-solder the gps chip on top-that is all I can see that looks very different from the first.

 

[cerving]

It's usually not the grounding channels, it's usually one of the "half moon" pads. Check them carefully with a 10x jeweler's loupe... look for pads where the half moons aren't filled in.

 

[downhill_D]

I will work on it today! I can see some spots but need to use a higher mag magnifier and a better tip. Thank you Chris!

 

[downhill_D]

I went over the board very closely and re-soldered or fixed the gps chip connections and the rf module connections (all under magnification) and it looks pretty clean. The board flashed the two lights on the rf module on power up and then eventually the amber led starts flashing (but still no red flashing rf chip at this point) and it won't connect to the receiver. I tried connecting the tx and programmed the frequency and code and I think it worked but it is not connecting to the receiver (and not flashing on the rf chip). Neither the receiver or the tx seem to be connected to each other.

Can it be fixed? I am not sure what to do at this point with this one.

Thank you

 

[cerving]

1) Do you have a jumper on the RUN pins?
2) Is the red LED on the RF module blinking once per second?

Getting the amber 1S LED but no RF usually means that you're missing a solder joint on the GPS module OR one of the resistors around it; they're necessary to set up the serial feed to the RF module.

 

[Tractionengines]

The RFModule lights at power up means its getting power and LEDs are correct polarity. If amber led is blinking once per second after a few minutes then GPS module sounds like its working. But not passing the data to the Hope RF Module. The RF Module Red light not blinking means its not sending any data out. (So nothing for receiver to get.)

Check the resistor values. Also look at traces between the modules. It's not impossible that a trace is broke. Or lifted from being overheated.

(I see Cris posted as I was typing. THANKS CRIS.)

 

[downhill_D]

Thank you, will do!

 

[downhill_D]

I tested the resistors and two of three had values just below what they were supposed to be. I'll replace them with the extras today and hopefully that will resolve it. One was 2.19k ohms where it was to be 2.2k, the other was to be 330 ohms and was 329 ohms. Both were between the rf and gps modules so I removed them and cleaned the pads (pulled old solder with a copper wick). I will report back, I don't know that much about fine electronics but it seems to me the proper values are important (needed).

 

[downhill_D]

1) Do you have a jumper on the RUN pins?
2) Is the red LED on the RF module blinking once per second?

Getting the amber 1S LED but no RF usually means that you're missing a solder joint on the GPS module OR one of the resistors around it; they're necessary to set up the serial feed to the RF module.

1-yes
2-no

The rf red flashes once with the green on start up and then never blinks again, only the 1s led does.

I am soldering new resistors on today as the values were not exact. Since you provided a few extras with the kits I will be able to use those.

Thank you
Davin

 

[cerving]

If you get the 1S light then the GPS is working internally, however you're not getting the data to the RF module. Check the solder joints on the side of the GPS module really, really good with a 10x jeweler's loupe... you should see the "half moon" pads filled with solder. BTW, those differences in resistance are well within the tolerance of the resistors (5%).

 

[downhill_D]

If you get the 1S light then the GPS is working internally, however you're not getting the data to the RF module. Check the solder joints on the side of the GPS module really, really good with a 10x jeweler's loupe... you should see the "half moon" pads filled with solder. BTW, those differences in resistance are well within the tolerance of the resistors (5%).

I used a digital celestron microscope and figured out where the issue was! Thank you again! All fixed and functioning! Tracker works as it is supposed to now. It was the half moon pads on the gps AND one gps half-moon pad didnt have enough solder going out towards one of the traces to a resistor.

 

[FredT]

Double check the frequencies and codes on the receiver and transmitter. Since you can can't check the transmitter, just reprogram it to match that of the reciever.