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Yeah I figured, so I bought a couple earlier today, because I still have a couple of Derek's PCB's.
 
dingle said:
welp that didn't take long to screw up. lol

Working on the transmitter and when soldering C2 it appears the left conenction is bridged to the left of the 3 connectors on U2. Using my meter set to olms I get a signal if I touch both spots. sigh. So I've been working at trying to remove that bridge for over 30 minutes now. I figured the braid I have would pick it up but the braid seems to either absorb very little or none at all and every time I recheck with the meter I still get a signal. I'm assuming that the design of the board isn't giving me that signal right, as in if they were hooked up correctly I wouldn't get a olms signal right?

Any suggestions on how to break the bridge. It appears to be a super thin layer that is connecting the two and the braid just isn't doing what I though it would. This has been way harder than I predicted it would be. :eek:

33972497246239167765.jpg
Click to expand...

sorry it took a while to respond to this. That is the way the circuit is supposed to be which is why you can't remove the bridge. you can check this on your other board. as long as there isn't a short between the two pads on the cap, your ok.
 
Derek said:
sorry it took a while to respond to this. That is the way the circuit is supposed to be which is why you can't remove the bridge. you can check this on your other board. as long as there isn't a short between the two pads on the cap, your ok.
Click to expand...

Is there a way to test for a short before soldering the rest of the stuff on?
 
Derek said:
Yeah. Use an ohmmeter.
Click to expand...

Ok, I did that between the two and I'm showing a connection. I wasn't sure how the board was wired if that was expected or not. I'm thinking I'm going to need another receiver board. :eek:
 
What was the reading you got? Since the voltage regulator is installed, you should see some resistance - probably 1 k or more. I'd have to measure a board myself. Unless it is a few ohms, it is probably normal. If you have another one already built, compare the two.

Also, that looks like the tx, not the rx.
 
Derek said:
What was the reading you got? Since the voltage regulator is installed, you should see some resistance - probably 1 k or more. I'd have to measure a board myself. Unless it is a few ohms, it is probably normal. If you have another one already built, compare the two.

Also, that looks like the tx, not the rx.
Click to expand...

Yea TX sorry. It pegged the meter out so it appears to be a full connection.
 
Here is what the circuit looks like:

TX power in closeup.png

Positive battery voltage comes in on the left battery terminal to the top pad of c2 then continues to pin 1 of u2. From there it goes under u2 to pin 3 of u1.

Ground comes in on the right battery terminal to a plane that covers most of the top of the board. I wish I could change the color but I can't find a way to do that easily. :( The bottom pad of c2 picks it up and then continues with a thick trace to pin 2 of u2 to provide ground to the voltage regulator.

Hopefully this will help you try to find out where the short might be occurring.

Derek
 
Derek said:
Here is what the circuit looks like:

View attachment 159067

Positive battery voltage comes in on the left battery terminal to the top pad of c2 then continues to pin 1 of u2. From there it goes under u2 to pin 3 of u1.

Ground comes in on the right battery terminal to a plane that covers most of the top of the board. I wish I could change the color but I can't find a way to do that easily. :( The bottom pad of c2 picks it up and then continues with a thick trace to pin 2 of u2 to provide ground to the voltage regulator.

Hopefully this will help you try to find out where the short might be occurring.

Derek
Click to expand...

Got the replacement. Thanks Derek! While I was waiting I practiced on the first one and I think I found my problem(s). First, I was using a screw driver (blade) tip and I was trying to verify my solder joint by using my helping hands magnifying lens. I got an inexpensive loupe lens from amazon and wow, what a difference. I can see the solder joint perfectly and don't have to guess if I have a good solder or not which allows me to use less solder. I'm pretty sure all of those combined led me to my first doomed experience.

12939830379857524331.jpg


I will clean up the flux when I'm done with all the soldering but I'm pretty happy with the way this one is turning out. :cool:
 
6x6 said:
Thought I might help out the next person - LED's have a positive and negative side. (I destroyed 3 because I soldered them on in the wrong orientation and didn't have 2 solder guns to remove them properly)
Knowing which side is which before you solder them on is a good idea! So I did a little investigative work. Found a pdf from manufacturer. You can tell which side is + & - by the way it is packaged, and if you have good eyes (or magnifying glass) lay it on its side.
Here is a pic of the 2 helpful aids in determining + & - (hint, C is ground, A is positive) First picture is in the tape packaging. Second is loose LED, top and side view.
View attachment 135986
View attachment 135987
Click to expand...

So from this post I thought I knew which way to install them, but I still got it wrong and had to remove and flip them. :eek:

This may help others. If you look at the LED from the top you can see the copper lines inside. There will be one end with a circle type shape and the other will have just a single straight bar. The single straight bar side go towards the outside of the pcb and the circle side goes towards the middle/inside of the pcb.

33368004379518378024.jpg
 
On the RX, the usb connector the spot to put it has 4 large pads for securing it (im pretty sure that's what they are for). The two side ones, no problem, am I supposed to use the two middle ones as well? If so, any suggestion on how to do that before I try it?
 
dingle said:
On the RX, the usb connector the spot to put it has 4 large pads for securing it (im pretty sure that's what they are for). The two side ones, no problem, am I supposed to use the two middle ones as well? If so, any suggestion on how to do that before I try it?
Click to expand...

Well, the easy way is to only solder the two tabs that stick out on the sides. That's what I do. I've tried to solder the two pads under the connector, but wasn't able to apply enough heat even with two soldering irons with hot tips. I think you really need to use a tiny amount of solder paste which I don't have. You definitely don't want to put a lot of solder on those pad as it could end up in the connector.

Even without those pads soldered, the connector is fairly strong as long as you don't drop the rx with a usb cable plugged it. :)
 
dingle said:
So from this post I thought I knew which way to install them, but I still got it wrong and had to remove and flip them. :eek:

This may help others. If you look at the LED from the top you can see the copper lines inside. There will be one end with a circle type shape and the other will have just a single straight bar. The single straight bar side go towards the outside of the pcb and the circle side goes towards the middle/inside of the pcb.

33368004379518378024.jpg
Click to expand...

That's not a led, that's a goldfish!

The first time I studied the data sheet to figure out which side is the anode while still in the tape. Then I carefully removed it from the tape and soldered it in place and it worked. After that I just looked at an already assembled board to find the right orientation. Cheating, but it works!
 
dingle said:
Got the replacement. Thanks Derek! While I was waiting I practiced on the first one and I think I found my problem(s). First, I was using a screw driver (blade) tip and I was trying to verify my solder joint by using my helping hands magnifying lens. I got an inexpensive loupe lens from amazon and wow, what a difference. I can see the solder joint perfectly and don't have to guess if I have a good solder or not which allows me to use less solder. I'm pretty sure all of those combined led me to my first doomed experience.

12939830379857524331.jpg


I will clean up the flux when I'm done with all the soldering but I'm pretty happy with the way this one is turning out. :cool:
Click to expand...

That looks perfect! Nice job!

I can't build these without a microscope. My eyesight is terrible.
 
If you're going to be soldering SMT by hand, you need really fine solder... try Kester #245, p/n 24-6337-8834. It's a 63/37 alloy, .020", no-clean flux. It's smaller than the SMT pads, so that makes it much easier to use than the standard .032" 60/40 rosin-core.
 
cerving said:
If you're going to be soldering SMT by hand, you need really fine solder... try Kester #245, p/n 24-6337-8834. It's a 63/37 alloy, .020", no-clean flux. It's smaller than the SMT pads, so that makes it much easier to use than the standard .032" 60/40 rosin-core.
Click to expand...

I've been putting the solder onto the tip of my iron and using that to apply it. I don't think I could hold the tweezers, iron and solder all at the same time (I think that is what you were implying?). I am using .03 solder currently.
 
dingle said:
I've been putting the solder onto the tip of my iron and using that to apply it. I don't think I could hold the tweezers, iron and solder all at the same time (I think that is what you were implying?). I am using .03 solder currently.
Click to expand...

that will work. my approach is to put a little flux on the pads of the part I'm soldering and then add a tiny amount of solder to just one of the pads. then, with tweezers, hold the part in place and touch the iron to the pad that has solder on it. the part won't move after that and you can do the other pins. finally I come back to the first pin and touch it up if it needs a little more solder.

easy peasy.
 
If it's a larger SMT part you might want to use a little masking tape to hold the part down while you solder it. That's not going to work for the resistors or caps, of course, but it works fine for MCU's and the like.
 
So the TX tested out ok green light came on I was happy. Built the RX and went to test it and no green light. It took me a bit to come to the realization that my switch hadn't come in yet and it was required to turn the board on. :eek: details.. lol
 
yeah, the switch is a minor detail. :)

You can bypass the switch with a little wire if you really want to test it.
 
Derek said:
yeah, the switch is a minor detail. :)

You can bypass the switch with a little wire if you really want to test it.
Click to expand...

Are these the two spots I would need to jump for the switch? I may have to use a different switch so I'm trying to figure out exactly what I need.
08032753373846854967.jpg
 
do the xbee or gps need to be installed to get a green light on the RX? I'm not getting a green light and I've tried flipping the LED. I know the board is getting power. The top circle pin in my previous posted image of which ones to jump, I did that and nothing. But I know power is getting the there because in my testing I accidentally touched my jumper from the top pin on the switch to the bottom LED post and it lit up. I checked all my caps and res and they appear to have good connections. I don't see any other solder spots that look like they should cause an issue.

what's the best way to track down the problem. It looks like only R3 is being used in between the power and the LED? Is that right?
 
No, youy don't need the radio modules for the green led to work. Just power. Use a voltmeter to check the output of the regulator. It should be 3.2 volts.
 
I ordered on of these adafruit gps modules for eval:

790_MED.jpg


https://www.adafruit.com/products/790

The good news is it is tiny! Way smaller than the up501. Here is a shot with it placed on the xbee radio next to the up501:

gps comparo small.jpg

In theory I could make the tx about half as long by placing this on the backside of the board between the xbee pins. The downside to this approach is you lose the flat mounting surface, but that might be ok.

The biggest downside it this part will be much harder to solder. I think I'd have a hard time myself, and I feel I have above average soldering skills and really nice equipment. :(

The other potential downside is this antenna is smaller and I don't know how it will compare to the up501. I know the up501 works really well and I'd have to build a new pcb to try this one out. The chips are basically the same, so any performance difference should be a result of the antenna.

I'm on the fence if I'm going to make a new pcb for this part. The up501 still seems to be available, is proven to work and very easy to solder onto the board.

Has anyone tried one of these gps modules?
 
Derek said:
Has anyone tried one of these gps modules?
Click to expand...
I mentioned it back in post #128 upthread. :)

I haven't tried this particular one, but I used the last generation of it (MT3329 chipset) and it works OK. I don't think soldering it will be that bad, but I haven't tried soldering it directly to a PCB.

Tough call on whether to make a new PCB. I'm sure there will be better modules coming out all the time. Multisystem (GPS, GLONASS, Galileo, Beidou) modules are becoming available, and they might help for periods when there aren't a lot of GPS sats in view. I've had rockets lose lock or have very poor lock at these times.
 

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