Has anyone ever had problems with the RF module on the EmonTX?
My new EmonTx was constantly hanging and rebooting in the call to rf12_sendWait(2) in send_rf_data. If I comment out this call, it runs fine (but sends no RF data of course).
I noticed that the chip on the RF module was running very hot, so I figured that it was probably dead. I checked for any obvious shorts on the PCB, and saw nothing amis.
After much hassle, I eventually managed to desolder the RFM12B (breaking two PCB pads in the process) which I'm now going to replace.
One possible issue is the potential for a short between the module and and the underlying PCB, most of which is covered with ground plane. Is this ever a problem I wonder? In my case, there was a tink speck of loose solder between the two boards, which might have been the cause.
Now need to order another module from Maplin..
Re: EmonTX - failed RF module?
Hi Robin,
Sorry to hear of your problem. If the chip on the RFM12B wireless module is not, that is not good! I've never felt one get hot, I think your correct with your diagnosis. Do you think the module was DOE or damaged to to soldering?
Re: EmonTX - failed RF module?
I have no idea if the module was DOA or whether my poor soldering shorted something under the module which caused the problem. In either case, there was no way of removing the module without being destructive, so we will never know...
This does raise a question though: would it not have been better to have used the version of these modules with the pin headers (DIP) rather than SMD, given that these are being built by hobbyists?
Re: EmonTX - failed RF module?
We have found the DIP version to be more expensive and difficult to get hold of. I guess we went for the SMT version since we based the emonTx on the JeeNodes. The JeeNode kits come with the SMT version, I found the soldering to be not too bad since the pads are quite large for SMT.
Re: EmonTX - failed RF module?
I can also confirm i bodged adding the RF module to all 3 units.. one i managed to remove but remove the pads also, Luckly the guys at work fixed it back with some fine wire and rubbing tracks to get enough copper to solder to.
The other 2 solder did get under the units and short it. Again the guys managed to remove them with out doing the pads and re do them..
If there is an option to make them plug in or someother way off soldering them it would be great, I really did find these to be a pain. Im not completly usless with an iron.
Re: EmonTX - failed RF module?
Glad it's not just me!
Soldering them is easy - it's unsoldering them when they don't work that is virtually impossible!
Any clues as to how 'the guys at work' managed to remove them? Do they have a special iron with a very wide bit?
Re: EmonTX - failed RF module?
Just soldered on a new RFM12B module on my emonTx - now all seems to be working correctly. Well - the send_rf_data code no longer hangs and the module runs cool. Can't see if it is actually transmitting anything until my new module arrives and I've soldered it to my GLCD module (currently without an RF module - but that's another story).
I needed to solder a wire from the RF module to the CPU due to a broken track and pad - quite fiddly but not too bad.
Re: EmonTX - failed RF module?
Desoldering SMDs
There appears to a kit based on the principle of applying a low melting point solder that displaces the normal solder, then the device is lifted off the board. It is reported here and available from Farnell.
If anyone tries this, please post a report.
Re: EmonTX - failed RF module?
Thanks for the link Robert, that looks really intersting. It seem to work well. I thought the only way was with a reflow hot air station. It's a bit more expensive but not out of reach of enthusiastic solderers: http://www.rapidonline.com/Tools-Equipment/Weller-WHA-900-hot-air-station-300670/?sid=079e35ee-ea8d-4d97-9dac-7fef44fb6e00
@robin good work! Gald to hear you have got it working.
Re: EmonTX - failed RF module?
glyn.hudson
I envisaged a custom-made bit on the end of a welding torch! ! ! (or at least a soldering iron in the hundreds of watts department, usually seen in the hands of tinsmiths and roofers) - something to heat up all 14 joints simultaneously. It might just be practical if you could obtain a large block of copper to make a bit that would reach all 14 joints of the RFM12B in one go - pre-heat it with a blowlamp - apply - lift?
I would put money on needing a special nozzle for the Weller to do any good with the RFM12B - not much change out of £1000 then!
Then I briefly wondered about a paint stripper gun with a custom home-made nozzle, and decided there would be too great a risk of setting the gun on fire.
Re: EmonTX - failed RF module?
They guys at work did use a Hot air station. Took them all of about a min to do.. Sickening. Even managed to re-fit it and re wire it with some super fine wire to other pads / tracks.. Looks a mess but it does work fine..
You also dont have to do all the pads. I think only some of them are connected so that can make it easier.
Re: EmonTX - failed RF module?
Yes - I noticed that only two pads on the left side are used - fortunately that was the side I damaged most. So, only one wire was needed to fix it up.
I pondered using a hot-air paint stripper gun, but without a lot of time to make a custum nozzle I thought it would do more harm than good!