Fourth generation iPhone. Repair is straightforward, but the front glass and LCD must be replaced as a unit. GSM / 8, 16, or 32 GB capacity / Model A1332 / Black and White.

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A new method to fix backlight issues?

My iPhone 4 incurred full water damage (all indicators are pink) however the only issue is the backlight.

The issue is most likely due to the coil and IC.

Sending the phone in would cost me $100 at least to repair without guarantee, and a replacement would cost $199 through Verizon.

I don't have a 100x microscope nor steady hands to solder a new coil and/or IC.

After further research I found the LED backlight cable from the front screen and was wondering if I could run those cables outside of the phone and power them to an external battery with a regular on/off switch.

The idea is that I would turn on both the phone screen and the backlight separately (it's a slight hassle but saves a lot of money.)

How much voltage would I need for the 6 LEDs?

What revision would I need to make to my plan?

-Thank you

Answer this question I have this problem too

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UPDATE

Replacement screen did not fix the issue. With the replacement screen, nothing has changed. LCD turns on, touch screen works, all components work except for the backlight

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Oh my now I don't have any ideas but what you are planing Is a little crazy just to save a few bucks. All you might need is just a new screen as the other probobly got damaged with the water.

I would try a new screen before you start Frankensteing the iPhone 4

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well the screen works fine, I can text, make calls, browse the internet, I just can't see. It's highly unlikely that the issue resides with the LEDs themselves or the cable. I haven't taken the phone apart yet because I need the right screwdrivers, but I'll also be checking if the connections are fastened well or clogged with gunk.

I appreciate your input and am still considering all my options, thank you

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Hi there I have seen plenty of water damaged iPhones that flicker and a new screen has solved the issue I would try that out first

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Thank you con,

I will go ahead and try this first

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Draden , in principle I like the idea. I would not even think about applying power to the coil or the IC, just to the connector. Pin 2,4, and 6 are for the backlight. As for how much voltage, you could use a 5V power supply and a potentiometer, start off at 0V and go up until it works. In practice it's a bit more complicated, you can't just apply power to the coil etc. By the time you have done the microsoldering and have it all figured out, and if you do not power surge any other component on the logic board, it will cost you more than a new display. Great approach nevertheless. Hope this helps, good luck

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Great, the pinout helps a lot! I'll revert back to my original plan and your revision if the screen replacement doesn't work out.

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So I'm quite a bit new to circuits, what are all three backlight pins for?

So apparently I cannot simply add power to the two cables from the backlights? http://www.chinahcs.com/images/iphone-4-...

Thank you all as always.

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This could be wrong and could destroy your LCD. I would suggest to take a multimeter and measure what you get on pin 2 and 4 (one probe to ground and measure with the positive one on the connector.) I have seen it done on a 3G by placing a jumper from BL-CA to BL_Cc on the flex, but this could backfire into the IC.

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Just replace the screen and you will be fine :)

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Thank you i will try that :)

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The backlight coil generates something around 15V-20V--so I would consider this plan dangerous.

Why would you think it would cost $100 for a backlight repair? You can surely get this done for more like $50.

good luck!

jessa

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There is no one here in canada who works at component level repairs in iphone 6.

I have the same issue with my iphone 6

Water damaged but thanks to your videos jessa

I followed every step and cleaned the board with ultrasonic cleaner, Branson ec in canada was a rare find :-)

It came alive everything works fine calling video camera audio wifi all work great but no backlight even with a new screen.

I need help here

Sequencerz at g mail

Sal

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Hi Draden!

I see this post is super old, but I just arrived here from randomly looking posts and wanted to share a bit, maybe someone stumbles here looking for solutions. And, as what I’m going to tell applies for many mobiles, welp! I’ll just share.

So! As much as I likes your crazy Frankenstein idea, I’ve to tell you that it falls quite fast into the crazy part only :). There are a bunch or reasons for your plan to possibly burn your phone down, and in the best of the situations, just make the underlaying problem worse.

The phone backlight works quite straight forward in terms of components, as you will only find 5 parts concerning directly the backlight:

  1. The power management IC
  2. The coil
  3. The diode
  4. The Filter
  5. And the LCD connector.

Most of the time the problem resides in one (Or many) of the last 3 (The diode, filter or connector). I’ve read many times that the problem can be on the coil, but every time I’ve encountered a backlight problem’s never the coil. So, just start looking at this three bad boys before getting it with the coil, as it’s quite a sturdy guy.

Usually, when there’s water damage there’s water corrosion on the LCD connector, and always the most affected connectors are the ones related to the backlight, as the pins are carrying around 20v on them, making them usually black and burned more easily damaged. If this is the case, you may need to clean and reflow the contacts.

The second part to check would be the filter, as they are usually the culprit when the backlight isn’t working… Almost always. The filter is a small black and silver ceramic component, usually sitting near the lcd connector (In some iPhones, or iPads, there can be more than one… But for the iPhone 4 and 5 there’s only one for sure). Take you multimeter and test the continuity on this piece, if you get no continuity, then you got your felon (You can usually SEE the damage too, as the ceramic splits, or breaks, and sometimes you can see a little point of the silver solder below). Just take that bastard out and replace it, in case that you can’t do that (Many times they get stuck, really stuck) just create a jumper there with a tiny piece of conductor. This will fix the issue, but maybe you’ll see some small flickering from now on in the backlight when calling, as this is what that filter worked out.

Third, but not last, there’s the backlight diode (Sometimes… Weirdly named “Backlight IC” but… it’s not an IC, just a diode). To find it just follow back the way of the filter, use your multimeter to get continuity from it to the next component looking like a… welp, a diode! When you find it, just test it like you would test a diode with the multimeter (On diode testing mode) and also get note of the direction of it (this is very important!), if it’s damaged, replace it using the same direction the old had.

If after testing with a GOOD, checked, perfect screen, still doesn’t work, then you can continue down the line and check the coil (It’s never the coil) or the IC, both rarely fail. Just test the coil for continuity and change if needed… And if the coil is ok, and then the IC is the problem… Just… Take it to repair or buy a new Mobo. As reflowing this is too complicated without a lot of experience and good tools.

I hope this helps!

Cheers!

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Draden will be eternally grateful.
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