pleriche
I successfully replaced an iPhone 5 battery today, but the backlight didn't work. The owner told me it hadn't worked before the old battery had died.

However, I noticed 3 (I think) bare solder pads at the point ringed in yellow in the pic but didn't have a disassembly guide to hand against which to check whether this was normal. It appears they should be covered by a small foam square as in the picture.

Are these solder pads something to do with the backlight, possibly test points used during manufacture, and could it be the cause of the backlight fault if they were shorting to the LCD back plate? If so, is it likely that anything else would have been damaged?

And a horrible thought occurs to me: the old battery was badly swollen - if something was shorting here, could this cause battery discharge and death, or even fire?

Regards - Philip

Image1.jpg
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TheMicroGuys
Going from the top of my head there is nothing of interest in that yellow circled area apart from a bracket and screw. There is a row of 3 capacitors and some smaller resistors just to the left of the top lcd connector which are related to the LCD, but these are under the metal plate. It has been a while since I last looked at a iphone 5 so my answer is based on memory. It would be helpful to see a picture of the actual area on the board you are referring to
The Micro Guys Ltd
WEB   http://www.themicroguys.co.uk
EMAIL service@themicroguys.co.uk
TEL    01803 467 477
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Steve
Ah i know what you mean, these solder connectors are for the back-light power (the same power that you tap into for the LED logo modification on the 6 series) 

You could try just popping a little electric tape / Kaptan tape over to insulate and give it a try.

If not we do sell the back lights that just solder in place, its a pretty easy solder job and sames the cost of the screen

https://www.replacebase.co.uk/apple-iphone-5-replacement-lcd-screen-backlight-sheet-oem/
Steve Garner | Replacebase Founder 

Need support? my team are happy to help - sales@replacebase.co.uk | 01604924700
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Steve
Ah i know what you mean, these solder connectors are for the back-light power (the same power that you tap into for the LED logo modification on the 6 series) 

You could try just popping a little electric tape / Kaptan tape over to insulate and give it a try.

If not we do sell the back lights that just solder in place, its a pretty easy solder job and sames the cost of the screen

https://www.replacebase.co.uk/apple-iphone-5-replacement-lcd-screen-backlight-sheet-oem/
Steve Garner | Replacebase Founder 

Need support? my team are happy to help - sales@replacebase.co.uk | 01604924700
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Bytesize
if that tape wasn't on the backlight solder points then if they got shorted it may have blew the backlight filter which would require board level repair, I am not sure what other guys charge for board level repair but I would assume the repair cost will be more than replacing the iPhone.
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Steve
Im not export on board level but it maybe the backlight coil on the board if it is board level - I don't think these are too much, maybe £45 at a guess for a repair.
Steve Garner | Replacebase Founder 

Need support? my team are happy to help - sales@replacebase.co.uk | 01604924700
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Bytesize
it's almost never the coil unless it's an iPhone 6+ where I have had 2 this week where it was the coil. I imagine there are some out there that do repair on a per problem basis however I have seen many that say it's coming in for a backlight and and the next you know you have the device and the backlight is the least of their worries so I only offer a solution based service, I don't care what the problem is it's a 1 off fixed fee and if I can't repair it then there is no fee.

Anyway I digress, the most likely issue will be a blown filter and/or possibly diode
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Steve
Sounds like you have better experience then me with BL, I'm basing my assumption more so on a similar situation with the iPad minis (I know the coils are pretty common on these.

Ever have any sourcing issues with components? we have been considering taking a range of components for the Apple range.

Cheers

Steve
Steve Garner | Replacebase Founder 

Need support? my team are happy to help - sales@replacebase.co.uk | 01604924700
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Bytesize
I would love to have a local Company(UK) to buy components from, at the moment Aliexpress is my friend for ic and coils, capacitors/resistors and diodes are freely available from digikey and rs components, but 1610a3 tristar chips, tigris, touch ics' for the iPhone 6/6+ also the glass diode in the iPhone 6s are tricky to get hold of, baseband pmic, fpc connectors for most devices(it's amazing how many repair shops think the flex has to be forced in and not just a firm click) I am sure others may have some other items to add
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Steve
Leave bat with me. I will do some research and see what we can get in. 
Steve Garner | Replacebase Founder 

Need support? my team are happy to help - sales@replacebase.co.uk | 01604924700
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TheMicroGuys
Steve
I would second what bitesize said. There is a void in this country when it comes to some components. A lot are available from RS for a few pence and even if unavailable can be substituted  with components within an acceptable range. High P&P makes small orders too costly.

For more specific components not found from the usual outlets Aliexpress is the only economical option I have found. A lot of these components are finding their way onto Ebay with UK based sellers but convenience and speed of delivery is negated by the high component cost.

For example ISL6259 is a power management chip and a common component found in many Macbooks. There is only one UK seller on Ebay who has sold a total of 85 singles at £3.95ea and 40x3 packs at £8.50ea. Aliexpress will sell me 10 for £3.78 (38p a part)!

I have copied my last order from Aliexpress and where possible paired it with the same part from the lowest priced UK Ebay seller. As you can see this is being exploited and will not last forever.   Sooner or later someone will come along and put these sellers to shame ans still make a decent profit. I would do it myself if I had the time. 

ISL6259   PMIC    Aliexpress  10 for £3.78.   Ebay 3 for £8.50 
ISL95870 PMIC    Aliexpress   2  for £2.24    Ebay not available in UK
TPS51125 PMIC   Aliexpress   5  for £1.16    Ebay 1 for £3.50
TPS51916 PMIC   Aliexpress   2  for £1.68    Ebay 2 for £5.50
RJK03E0  Mosfet  Aliexpress  5  for £3.95    Ebay not available in UK
RLK03E1  Mosfet  Aliexpress  5  for £4.00    Ebay not available in UK
RJK0216  Mosfet  Aliexpress  5  for £5.07    Ebay not available in UK
AON6405 Mosfet  Aliexpress  10 for £2.92    Ebay not available in UK (discon can be subbed)
Speaker FPC for Macbook/Pro Ipad   Aliexpress 10 for £11.29   Ebay 1 for £5.29
The Micro Guys Ltd
WEB   http://www.themicroguys.co.uk
EMAIL service@themicroguys.co.uk
TEL    01803 467 477
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TheMicroGuys
Also just to add BGA stencils are another product in the same state and even the solder balls can be hard to find.
The Micro Guys Ltd
WEB   http://www.themicroguys.co.uk
EMAIL service@themicroguys.co.uk
TEL    01803 467 477
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Bytesize
yeah, very good quality stencils are an added bonus, I lost count how many "good quality" stencils I have bought from ebay that turned out to be absolute crap, a good stencil is half the battle of reballing, I don't mind so much about solder balls as I prefer solder paste
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pleriche
Returning to the original theme of the thread, I put a piece of PVC tape over those solder pads on the lad's iPhone the other day but it made no difference. I told him he could get a new screen and we could try that but since as someone suggested something might have blown on the motherboard there was no guarantee it'd work.

But it should should presumably be possible to measure the voltages on those pads, if you knew what they should be (though it'll be higher with open circuit backlight), to determine whether the driver on the mainboard was still ok. Can anyone enlighten me?
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Bytesize
closing the gate after the horse has bolted will never work, if the backlight has already blown then this would need to be addressed first, check for continuity on the backlight filter and if it's ok then for a short to ground on the backlight anode line

checking for voltages without the screen will only show VCC_MAIN voltage as boost wont happen until a screen has been detected
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