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

[cporta]

Thanks. What type of screw is used to take the case off? Torx? What size?

 

[ceroberts75]

Oh, I understand - you're talking about the indicator on the charger, not the 1520 itself. I was under the impression that the device itself charging charging for an instant, then stopped. So, just to confirm, none of you have ever seen the 1520 itself start a charge, then stop, from just having the Qi coil (with no electronics) installed, correct?

There is recurrent HF AC chirp that starts the process (i.e., the "selection" phase). This is commonly referred to as an "analog ping". During this period, the presence of a receiver is detected (a load of "some sort"). If the Power Transmitter discovers a Power Receiver, the Power Transmitter may extend the Digital Ping, i.e. maintain the Power Signal at the level of the Digital Ping. This causes the system to proceed to the identification & configuration phase. If the Power Transmitter does not extend the Digital Ping, the system shall revert to the initial selection (object detection) phase. During the identification and configuration phase, the Power Transmitter identifies the selected Power Receiver, and obtains configuration information such as the maximum amount of power that the Power Receiver intends to provide at its output. The Power Transmitter uses this information to create a Power Transfer Contract. This Power Transfer Contract contains limits for several parameters that characterize the power transfer in the power transfer phase. At any time before proceeding to the power transfer phase, the Power Transmitter may decide to terminate the extended Digital Ping, e.g. to discover additional Power Receivers. This reverts the system to the selection phase. In the power transfer phase, the Power Transmitter continues to provide power to the Power Receiver, adjusting its Primary Cell (coil) current in response to control data that it receives from the Power Receiver. Throughout this phase, the Power Transmitter monitors the parameters that are contained in the Power Transfer Contract. A violation of any of the stated limits on any of those parameters causes the Power Transmitter to abort the power transfer, returning the system to the selection phase. Finally, the system may also leave the power transfer phase on request of the Power Receiver. For example, the Power Receiver can request to terminate the power transfer, i.e., "battery fully charged", reverting the system to the selection phase, or request to renegotiate the Power Transfer Contract: change to trickle charging the battery using a lower maximum amount of power, reverting the system to the identification & configuration phase. These control packets are sent approximately every 250 ms during normal operation or every 32 ms during large signal changes (i.e., you move the coil). Also during normal operation, the power transmitter sends power packets every 5 seconds. The power transmitter stops supplying power upon receiving an ?End Power? message, or if no packets are received for more than 1.25 seconds and the process repeats. While no power is being transmitted, the power transmitter enters a low-power standby mode, but remains active.

The presence of a Qi inductive coil only satisfies the very first part of the start-up sequence. It's possible that the charger's designed to turn on its indicator after an initial analog detection, or any time the transmitter is not in a low-power state. If that's the case, that could explain why the light on the charger blinks with just a coil present (no electronics). However, I would expect it to repeatedly blink every 1.25 seconds (or faster, since no communications are actually taking place between the "dead" coil and the power transmitter.

As for the "dashlight bulb" blinking - I was a little freaked-out by that until I realized you must be using a self-contained Qi coil circuit (i.e., from a Lumia 920), not just the Qi coil by itself. If not, and you had a charging plate that was inducing enough of a charge to light a bulb with JUST the coil attached, you'd essentially have an induction cook-top, not a cell phone charger.

Still, this is starting to get awfully deep. While I would love to hope that the Qi electronics survived AT&T's meddling, I've seen the two boards side-by-side, and I'm certain that the AT&T units I've looked at do not have Qi detection, negotiation or rectification electronics installed in them to support the coil-only scenario.

SonarTech

uh...thank you...for a GREAT and thorough response. makes absolute sense.

appreciate the time you put into this and this post.

 

[ceroberts75]

Thanks. What type of screw is used to take the case off? Torx? What size?

use a t4 torx.

 

[ceroberts75]

and then, be sure that you loosen the clips from the top left, then the top, then the right, and then work your way down both sides with a credit card, if you don't have an actual tool.

then the case will slide down from the bottom.

unlike the 1020, it does NOT fold up from the side, rather, it is from the top and the bottom of the hardware on the inside does have corners holding it into the case.

hope that helps.

 

[Sonartech]

use a t4 torx.

Actually, it's a T2 under the barcode label under/between the Micro-SD and Micro-SIM covers.

 

[superlawyer15]

sonartech, if you could please weigh in

what advantage, other than keeping the USB port open is there to this mod
as opposed to buying one of the USB Qi adapters?

I was hoping that it would yield a faster charge rate but your previous post stating that it charges at about ~650mah is about at par with what I'm seeing now with the USB method

I understand that it results in a "cleaner" look as the coil is inside the case, but is there any actual benefit as opposed to an aesthetic one?

 

[Citizen X]

sonartech, if you could please weigh in

what advantage, other than keeping the USB port open is there to this mod
as opposed to buying one of the USB Qi adapters?

Why would someone make a Qi adapter case for this phone? The non-at&t versions of the phone already have Qi built in. And the at&t variant already has the hardware in place to accept a PMA cover. Please post if you know someone making a Qi case for this phone. I'm afraid the only Qi option I've heard about is Sonartech's mod. I personally like it because it is clean and doesn't force you to always have a particular case on your phone.

 

[peacock93]

what advantage, other than keeping the USB port open is there to this mod
as opposed to buying one of the USB Qi adapters?

I tried one of these from Amazon. I wanted something until i modded my 1520. It lasted 2 days before it over heated! i just happened to pick my 1520 up and the back was screaming hot!! And I'm serious about how hot it was. I pulled my gel case off and i could smell the plastic melting. Luckily I had put a piece of paper between my 1520 and the coil to prevent scratches. I think that saved discoloring or any other damage to the back of my 1520. It still looks perfect.

 

[meir602]

I want to report that I have been using one of those adapters for more than two weeks and I am very satisfied with the performance. I have it stuck between the 1520 and the Nokia flip case. I folded over the flex cable to fit the coil in the right spot and it is wedged perfectly between the 1520 and the case. I did not even need to use any type of adhesive.

 

[Sonartech]

sonartech, if you could please weigh in

what advantage, other than keeping the USB port open is there to this mod as opposed to buying one of the USB Qi adapters?

I was hoping that it would yield a faster charge rate but your previous post stating that it charges at about ~650mah is about at par with what I'm seeing now with the USB method

I understand that it results in a "cleaner" look as the coil is inside the case, but is there any actual benefit as opposed to an aesthetic one?

There are a couple of key things that turn me off about these adapters. First, and most obviously, they eat the Micro-USB port. For people that frequently transfer large amounts of data to their device (I transfer and watch MKV's from 8 to 15GB in size to my 1520), loss of convenient use of this port sucks. How many times is that thin flex & super tiny-USB jack going to tolerate repeated plugging and unplugging before it breaks? Second, some of those 3rd-party Qi-to-5v USB adapters are made of shiť. I actually found one that used a 7v Qi solution that pumped its power through a tiny (and woefully underrated) SMD LDO to transform the 7v into 5v suitable for USB. Not only was the loss of efficiency awful, but the coil itself got hot enough to delaminate the adhesive and eventually the LDO burned out. That's not to say that all of these add-ons are poorly designed, but who knows which ones are and which ones aren't. I certainly didn't want to fart around with that...

From my perspective, part of the awesome convenience of wireless charging is that it's invisibly integrated into the design. Add-on chargers steal that magic away from the intended design of a good wireless charging solution (in my opinion), and I'm somewhat disgusted by designs like Incipio's fuǥly cases and other 3rd-party dorky stick-on "solutions" that ruin the elegance of my kick-aʂs, well-designed device. I didn't want a fuǥly phone, so I elected to take the risk of installing it internally.

Finally, I wanted a Nokia-approved part doing the work, and I had a supply of Lumia 920 coils that seemed to fit the bill. That part was just luck, but at least I won't have to worry about QA issues with the coil itself. Last thing I want to find out is that some cheap, 3rd-party coil roached my 1520 from the inside out. It would just be my luck, too -- I'd probably be using it one day, only to discover that the display was starting to discolor from the heat being generated by some ratty electronic garbage inside my phone. No thanks!

Anyway, the 920 coil feeds 7v at 700mA directly to the PMIC. That's going to be hard to beat with anything that passes gas over the USB interface, save a direct-to-wall charger.

Cheers,

SonarTech

 

[jssmarathon]

Sonartech......PLEASE
Do one for me!!!

I cant wait for the 938 and wont settle.

 

[superlawyer15]

Thanks for raising the quality issue in regards to the usb adapters.
That was my primary concern as I have no everyday use for the usb port other than to charge

While mine gets "warm" I have never felt it get hot enough to cause discomfort or discolor the device

I'm just weighing the pros/cons to ditching a method that seems to be working FOR ME at the moment versus what I consider to be substantial surgery on my device which approaches the limits of my technical ability

 

[Sonartech]

Thanks for raising the quality issue in regards to the usb adapters.
That was my primary concern as I have no everyday use for the usb port other than to charge

While mine gets "warm" I have never felt it get hot enough to cause discomfort or discolor the device

I'm just weighing the pros/cons to ditching a method that seems to be working FOR ME at the moment versus what I consider to be substantial surgery on my device which approaches the limits of my technical ability

I hear you. If we could locate a source for the flexes, it would be much easier to offer a completed unit for people such as yourself, but the lack of parts for this device and the nature of the hack really limits our options. I can't tell you how delighted I am that this modification didn't require making any changes to the 1520 main PCB. I was really sweatin' bullets for a while trying to figure out the differences between the International 1520 and AT&T's version. I only destroyed 1 AT&T 1520 wireless charging circuit working on this hack

 

[ceroberts75]

Actually, it's a T2 under the barcode label under/between the Micro-SD and Micro-SIM covers.

youre right. however, I also goofed at looking at my tool.

I use the T3 and fits perfectly. the t2 seems sloppy. the T4 as I said previously is wrong.

just checked to be sure what bit it was.

 

[superlawyer15]

Why would someone make a Qi adapter case for this phone? The non-at&t versions of the phone already have Qi built in. And the at&t variant already has the hardware in place to accept a PMA cover. Please post if you know someone making a Qi case for this phone. I'm afraid the only Qi option I've heard about is Sonartech's mod. I personally like it because it is clean and doesn't force you to always have a particular case on your phone.

I wasn't referring to a case with built in Qi, but rather the adapters what plug into the USB port then tuck in behind a case

 

[GrayW0lf]

It looks as though that new 32GB 1520 model does not include Qi charging as the images on the AT&T site show the 3 PMA charging pads that our 16GB models have. AT&T also seems to have made a point of not listing wireless charging anywhere on the 32GB model's page. That's a real shame.

 

[cporta]

Sonartech,

Can I use a flux-cored or rosin-cored solder or do I need a separate flux along with the solder? I'd like to simplify it as much as possible. My qi coli should be here today so I'm ordering my soldering components.

 

[peacock93]

Sonartech,

Can I use a flux-cored or rosin-cored solder or do I need a separate flux along with the solder? I'd like to simplify it as much as possible. My qi coli should be here today so I'm ordering my soldering components.

Flux core is fine but make sure to buy a small gauge solder with flux core. Also, pre-tin the wire and flex cable before soldering them together.

 

[Sonartech]

Recommend RoHS solder, Sn96.5Ag3.0Cu0.5 No Clean Flux, or Rosin Activated (RA). Here are some examples:

• Super Fine 26 AWG, 27 SWG: http://www.digikey.com/product-detail/en/796065/82-126-ND/2498924
• Fine 23 AWG, 24 SWG: http://www.digikey.com/product-detail/en/733001/82-111-ND/2498909

63/37 solder is OK, too, and is a little easier to use (and considerably cheaper to buy). If you want to stay RoHS like everything else in the 1520, you'd need RoHS solder (if you even care).

 

[peacock93]

I received my International Red Case and my Lumia 920 Qi coil assembly. I could not find a good way to use the International Flex cable in the international Case with the 920 Qi coil assembly. I thought about adding an extra pad but it just seemed like to much work.

So, I cut the PMA flex cable in my AT&T case and used it in my new International case. Worked great and I don't have the 3 contacts on the back of the case anymore.

Thanks again to Sonartech for all of his work! I finally have my Qi wireless charging on my Lumia 1520!!

Update: Worked great for almost two days. Now the light on my Qi charging plates just flashes. Once in a while it will start to charge and then stop and the Qi plate light flashes. Sonartech do you have any info about what the flashing light means? Not sure whether my 920 Qi coil assembly has crapped out or if I just lost my trigger.

I'll take it apart in the morning to troubleshoot but thought I would toss this out there to see if anyone has had this problem on this mod or other Qi phones.

Update2: Took my 1520 apart this morning and discovered that the +7Vdc solder joint on the flex cable was a tiny bit high. It had pushed through my tape and was touching a metal cover just below the contact pins. I removed a little solder and reinsulated everything. Put my 1520 back together and all is well again.