Qi Charging on a LUMIA 1520 AT&T phone (Solution)

[ryangadz]

It looks like same seller has a 1020 in yellow, white, and black. I wrote to them asking if it was indeed the Qi international variant.

 

[Benny Vallejo]

It looks like same seller has a 1020 in yellow, white, and black. I wrote to them asking if it was indeed the Qi international variant.

This thread is specifically for the 1520..but thanks for the info.

 

[flgregg]

I had found this and similarly emailed the seller who replied it was for the intl version hence has Qi.

Direct link to purchase outside of ebay B?squeda - 1520 carcasa

Shipping to US was 12 Euros

 

[Benny Vallejo]

I had found this and similarly emailed the seller who replied it was for the intl version hence has Qi.

Direct link to purchase outside of ebay B?squeda - 1520 carcasa

Shipping to US was 12 Euros

Thanks for the link. Seems like the eBay option including shipping is cheaper. Plus its covered by eBay just in case. But great for people who would like the Yellow variant that is not posted on eBay yet. Thanks again flgregg.

UPDATE: They just added the YELLOW variation to eBay.

 

[flgregg]

You bet.
By the way, ebay is GBP and their site is in euros so make sure to do the conversion on current pricing in both places when you are ready to buy

 

[coolhand33]

Anyone know how to get that frame in the video?

 

[Sonartech]

Guys, this doesn't work. You can't just swap the backs from an international 1520 to an AT&T 1520 and expect it to automatically start to work. There are multiple component differences on the 1520 PCB (5 components at least), as well as some unknown software changes that are required to (re)enable Qi-based charging on a PMA-based 1520. I've already tried this experiment, and I've already tried modifying an AT&T 1520 to match the components of a International 1520.

Again, I've already tried this, and the only conclusion I can make is that there are either more component changes to the PCB that I am not aware of, or there's a software part that needs changing as well (or both). The extra parts I mentioned are populated on an AT&T (PMA) 1520, but are mostly absent on the International (Qi-based) 1520.

Sorry for the bad news. :unhappy:

 

[5150 Joker]

Guys, this doesn't work. You can't just swap the backs from an international 1520 to an AT&T 1520 and expect it to automatically start to work. There are multiple component differences on the 1520 PCB (5 components at least), as well as some unknown software changes that are required to (re)enable Qi-based charging on a PMA-based 1520. I've already tried this experiment, and I've already tried modifying an AT&T 1520 to match the components of a International 1520.

Again, I've already tried this, and the only conclusion I can make is that there are either more component changes to the PCB that I am not aware of, or there's a software part that needs changing as well (or both). The extra parts I mentioned are populated on an AT&T (PMA) 1520, but are mostly absent on the International (Qi-based) 1520.

Sorry for the bad news. :unhappy:

At least you saved people the time, money and angst of having to make this discovery on their own. Plus it probably saved a few devices from being needlessly damaged while attempting to pry them apart. I'd suggest people instead purchase the RM-937 to get the full benefits of Qi wireless + 32 gb internal storage, that's what I did and am 100% satisfied with the decision. Plus I bought square trade warranty with it so it's fully covered.

 

[darth_furious]

I just took my 1520 apart and played with the contacts. Another post said it was ground on outside left and 5v on middle. I couldn't get that to work with the inner pins but it worked with ground as middle and 5v on left. It seems the ribbon for the att case switches the order/polarities between the phone and the charging pins. I wonder if the international one has it backwards to reverse polarities and make the qi case not work on an att phone. Just some thoughts....need to do more testing
Sent from my RM-940_nam_att_200 using Board Express

 

[darth_furious]

Guys, this doesn't work. You can't just swap the backs from an international 1520 to an AT&T 1520 and expect it to automatically start to work. There are multiple component differences on the 1520 PCB (5 components at least), as well as some unknown software changes that are required to (re)enable Qi-based charging on a PMA-based 1520. I've already tried this experiment, and I've already tried modifying an AT&T 1520 to match the components of a International 1520.

Again, I've already tried this, and the only conclusion I can make is that there are either more component changes to the PCB that I am not aware of, or there's a software part that needs changing as well (or both). The extra parts I mentioned are populated on an AT&T (PMA) 1520, but are mostly absent on the International (Qi-based) 1520.

Sorry for the bad news. :unhappy:

The eBay picture looks like 2 contacts for the qi. I know the 920 qi had 4 contacts, wc_det, wc_EN, gnd, 5v. The qi on this case looks much more simple. I don't see any communication going on or any software that needs to happen. I apply a charge to the contacts and it charges on my att phone. It just needs a current. I suspect the polarities are flipped for reasons states in prior post. That may be why
Sent from my RM-940_nam_att_200 using Board Express

 

[darth_furious]

I just tested the pins again and can confirm that the outside pin layout is different from the internal layout. It does flip in the ribbon

 

[Benny Vallejo]

I just testes the pinsa again and can confirm that the outside pin layout is different from the internal layout. It does flip in the ribbon
Sent from my RM-940_nam_att_200 using Board Express

I already ordered the international replacement. If I find that it doesn't work, i'd be glad to ship it to you so you can run some tests to see what you can find.

 

[cporta]

I just ordered one on impulse because I so want to have the wireless charging back on my 1520. I'll try it out and see what's up.

 

[Sonartech]

I just took my 1520 apart and played with the contacts. Another post said it was ground on outside left and 5v on middle. I couldn't get that to work with the inner pins but it worked with ground as middle and 5v on left. It seems the ribbon for the att case switches the order/polarities between the phone and the charging pins. I wonder if the international one has it backwards to reverse polarities and make the qi case not work on an att phone. Just some thoughts....need to do more testing
Sent from my RM-940_nam_att_200 using Board Express

This doesn't make any sense to me. Can you explain what exactly "worked" when you changed polarity using the left pin as 5v and the middle pin as ground? Did you successfully initiate charging? The Qi coil is inductive; there are no electronics on the antenna itself to transform the HF AC signal into a DC current. On an international 1520, the coil is connected directly to the two pogo pins on the same block - that third pogo pin on the lower right isn't even populated on the PCB. Additionally, I can confirm that the Qi coil has no polarity on those two pogo pins - it'll work either way (but only on the international 1520).

Originally, I had hoped that you could use a self-contained Qi receiver to negotiate a connection independent of the AT&T 1520 electronics, and just inject the right amount of DC voltage into the correct pins normally expecting PMA data/current. That didn't work (in my tests), with any polarity, at any voltage. I tried 2.5v to 7v. I don't, however, have a PMA charging back, and I don't know much voltage the PMA contacts expect to see, or if there is some kind of protocol negotiation handled by the charging back or 1520 that has to happen before the charging process begins. Perhaps the additional electronics around the AT&T antenna contacts provide the necessarily rectification or filtering needed to transform PMA-provided current into something the 1520 expects to see from either Qi or PMA-based methods. Damn, I wish I knew more about the PMA crap (beyond the fact that I hate it and AT&T for doing this to their customers).

The Qi electronics are normally built-in to the 1520, but I'm unsure if they've been removed or adjusted to work with PMA. As I mentioned earlier, there are a number of components right around the 3 pogo pins on the AT&T model that are not populated on the international 1520 - about 5 of them, including 1 small 2mm x 2mm 4 pin BGA. Those parts obviously are installed for some purpose to support PMA, but I don't know what they do. Beyond these known part differences, there may well be more, and there are probably firmware changes as well.

Getting all the pieces in place to make an AT&T 1520 work like an International 1520 could be tricky without knowing what pins expect what voltage. We need to understand what the PMA charing case sends to those three pins, then reverse-engineer it from there. It might just be easier to make a self-contained Qi charging circuit emulate a PMA charger, and present that to the 1520 instead of making hardware (and software?) modifications to the 1520 mainboard. Taking that little 2mm BGA off a thermal ground plane is impossible without destroying it. I've already "converted" one by removing these parts and I'm no closer to a solution...

 

[Sonartech]

<rant>
I too wonder if the LTE compatibility was worth losing both Qi charging and 16GB of memory. I seriously do question my decision now. Instead of clubbing baby seals, we should be clubbing AT&T for subjecting their customers to another Beta/VHS war, especially with all the other Nokia Lumia products AT&T sells supporting Qi-charging.

This has got to be a nightmare for their sales staff - trying to explain to their customers why they have to buy a different wireless charger for just the 1520 but not any other Lumias they sell. Clearly an AT&T marketing genius stepped into the AT&T-Nokia hardware negotiation when the deal was being struck for exclusivity, and AT&T's customers once again get to bear the brunt of their immeasurable stupidity. Makes you proud to be an AT&T customer, doesn't it? And what the heck was up with the decision to whack 16GB of memory out of the device? Hell, while they were at it, they should have eliminated the right auto channel and red pixels from the display. Makes about as much sense...:angry:
</rant>

 

[darth_furious]

The Qi coil is inductive; there are no electronics on the antenna itself to transform the HF AC signal into a DC current. On an international 1520, the coil is connected directly to the two pogo pins on the same block - that third pogo pin on the lower right isn't even populated on the PCB. Additionally, I can confirm that the Qi coil has no polarity on those two pogo pins - it'll work either way (but only on the international 1520).

The Qi electronics are normally built-in to the 1520, but I'm unsure if they've been removed or adjusted to work with PMA. As I mentioned earlier, there are a number of components right around the 3 pogo pins on the AT&T model that are not populated on the international 1520 - about 5 of them, including 1 small 2mm x 2mm 4 pin BGA. Those parts obviously are installed for some purpose to support PMA, but I don't know what they do. Beyond these known part differences, there may well be more, and there are probably firmware changes as well.

Getting all the pieces in place to make an AT&T 1520 work like an International 1520 could be tricky without knowing what pins expect what voltage. We need to understand what the PMA charing case sends to those three pins, then reverse-engineer it from there. It might just be easier to make a self-contained Qi charging circuit emulate a PMA charger, and present that to the 1520 instead of making hardware (and software?) modifications to the 1520 mainboard. Taking that little 2mm BGA off a thermal ground plane is impossible without destroying it. I've already "converted" one by removing these parts and I'm no closer to a solution...

I didn't know the 1520 case only had the qi coil without the circuit board. In the 920 the case had a qi coil connected to a small board that outputted a 5v charge. If this is the setup, it would be quite difficult to put the RM937 qi into the RM940. The RM937 literally has the electronics behind Qi built into the phone. Wow.... I really hate AT&T now

 

[mmcpher]

<rant>
we should be clubbing AT&T for subjecting their customers to another Beta/VHS war"</rant>

It's worse than Beta/VHS right now, because at least Beta worked and was available (until VHS overwhelmed it). But you can't even get a comparable PMA alternative, so its not just having the choice made for you, its being consigned to a lesser alternative. As has been said, ATT elsewhere supported Qi on other devices, so you'd think they'd wait until they had the PMA alternative ready, before they drew their line in the sand. Since there are no good PMA options right now (unless you're willing to go with the substantial bulk of the "official PMA case" (whenever its actually in stock), it's like starting the competitive war against Qi with a decimated army.

 

[cporta]

Man, I'm pretty bummed now. I got so excited after reading the article about having wireless charging again, but it seems like I bought the shell for nothing now.

Looking back, I'm not sure if losing the lte should have stopped me from getting the international version.

Hopefully we can get it to work.

 

[MrUNOwen]

So it sounds like the three pin connector turns to a 2 pin connection inside? For those who have taken their phone's apart, mind describing how the wiring is for the wireless charging.

 

[darth_furious]

So it sounds like the three pin connector turns to a 2 pin connection inside? For those who have taken their phone's apart, mind describing how the wiring is for the wireless charging.

The left 2 pins are together in one black plastic unit and the right one is encased in it's own black plastic. The left and center pins are power definitely and I have confirmed by applying a charge. The right one must be a communication pin