Z5 compact poor wifi and bluetooth range after battery change.

[aj19]

The battery on my out of warranty Z5 compact was performing poorly. At 100% charge on standby it would last about 6 hours and when browsing the internet it would drain rapidly from 100% to less than 30% in about an hour. I decided to change the battery...

After installing a new (non OEM) battery everything seemed fine. The phone lasts almost 36 hours on standby and a whole day with normal average use.

Unfortunately a few days after changing the battery I went to use bluetooth and realised there was a problem (this problem also includes wifi). The range on bluetooth is about 10 foot and wifi is even less. Standing by my router I get 4 bars, and if I step back a couple of feet I get no bars.

I have torn the phone down and made sure it's 100% clean and all contacts are good. I've flashed several different firmwares (except 6.1.1), and I'm currently on the latest nougat with all the updates, which was what the phone was on for several months before I changed the battery. I've run the phone in safe mode and that didn't make a difference. Maintenance/service tests all pass okay as well. I have tried the bluetooth devices on other phones and they all work without fauly. My only thought is that, the only thing that is different since changing the battery, is the battery! I no longer have the old original one to compare. Could the battery be causing interference maybe? idk. And everything else on the phone works as it should, plus this is the second Z5C battery I have changed too, and the first one I did is working fine.

Anyway.... any other suggestions that might help get this fixed would be very much appreciated.

AJ

[Uliwooly]

@aj19

who replaced the battery?

[aj19]

I changed it myself as it was out of warranty.

[Bhonder]

Maybe you touched the 2.4Ghz antenna. Check on some "tore down" instruction site if you find the original antenna position and compare it to the actual one.

Worse: you could have stripped away the antenna and now the wireless chip relies only on a part of the original one. In the 2.4/5 GHz band the antenna length is very important .

[aj19]

Well, funny you mention the antenna. I bought a new replacement wifi/bluetooth module thinking that somehow I did something to the original one, even though it seems relatively simple in design. Unfortunately replacing it did nothing.

Regarding 2.4ghz antenna, I've been reading up on wifi and bluetooth shielding/signal interference today and grabbed a few apps to monitor both outputs. I also tried two different firmwares last night and I'm back on 33.2.A.2.33 and when the phone starts up from new (after a complete wipe in flashtool) I get 2 bars on wifi when I have previously not been able to get a signal, but, when the phone starts searching for a wifi connection the bars disappear and I have to go within 5 feet of the router. However with a range finding app for wifi the app picks up wifi when there are no bars, and I can get a download/data exhchange, yeah real confusing, lol (so with no bars I can acutally use wifi, barely).  I haven't tested bluetooth yet today as I've been at work. I will look into the tear downs a bit more, there are a few but they don't mention the wifi/bluetooth parts (apart from the antenna module). I will do more reading.

Thank you.

[aj19 · Accepted solution]

After closer inspection with a decent magnifier I think I have knocked off a couple of smd's from the underside of the motherboard directly under where the front camera connector it.

I have somewhat rectified the fault by puchasing a bluetooth transmitter for when the phone is static and I've upgraded my old 802.n router to a new ac one.

So I haven't actually fixed the fault but I'm able to use wifi at a decent range and bluetooth isn't an issue now.

[Gauner1]

I had a similar problem. When I was removing the battery, I also pulled off a smd component from the mainboard. It looked like coaxial connection socket. But since nothing was plugged in anyway, I didn't bother. But according to my own finding, this connection socket was used to bridge one PCB track of the mainboard to another, nearby the spring contacts that connect to the wifi antenna (which is coated on the plastic frame that sits around the battery). So I thought, this might have to do with my loss of wifi signal strength. I soldered a tiny piece of wire to two of the smd pads opposite to each other in the smarthphone lengthwise direction and viola: wifi signal is back to the fullest.

Sorry, I didn't take pictures.

[lobie81]

Hi mate. Are you able to give some more detail on what you soldered? I'm having exactly the same issue. Replaced my ear speaker and now my wifi is terrible. Looks like I damaged a small component between the rear camera and the antenna connectors on the left side (looking at the back of the phone).

This is the component I damaged (broke off):

This is what it looked like:

Any what it is, what it does and whether it's fixable? The antenna contacts on both sides of the phone seem to be fine.

cheers

[daniel1984uk]

I did the same today, adding the answer here in case anyone else does it. Id ripped the pad off directly opposite I needed to solder to too. So i used a single strand of copper  and soldered directly to the antenna springs. Was changing the battery because it went into a boot loop and the completely died, 0v not charging.