Flickering lights 2.8.1

[Griu]

Hi,

I have a Kindle Paperwhite 3 and it was working flawlessly. I opened it and try to do the jailbreak. I wasn't able to do it. I used a 3v serial cable with a shifter to 1.8v.

The problem is not that I wasn't able to jailbreak it, that's just a little background.

The kindle was working fine until the last update to 2.8.1. Now the screen flickers when I go above 10 in the light settings, and it doesn't really goes brighter either after that. The screen is fine, the lights are the problem.

I was wondering if this has happened to someone before. I tried letting the battery fully discharge and charging it again over night but it didn't do anything.

I talked to amazon but they couldn't do anything for me since I'm out of warranty.

Thanks in advance for your help.

[geekmaster]

Originally Posted by Griu

Hi,

I have a Kindle Paperwhite 3 and it was working flawlessly. I opened it and try to do the jailbreak. I wasn't able to do it. I used a 3v serial cable with a shifter to 1.8v.

The problem is not that I wasn't able to jailbreak it, that's just a little background.

The kindle was working fine until the last update to 2.8.1. Now the screen flickers when I go above 10 in the light settings, and it doesn't really goes brighter either after that. The screen is fine, the lights are the problem.

I was wondering if this has happened to someone before. I tried letting the battery fully discharge and charging it again over night but it didn't do anything.

I talked to amazon but they couldn't do anything for me since I'm out of warranty.

Thanks in advance for your help.

It sounds like a loose connection or bad solder joint, that is current sensitive (based on described symptoms).

[Griu]

Originally Posted by geekmaster

It sounds like a loose connection or bad solder joint, that is current sensitive (based on described symptoms).

I have opened it again checking for any loose cables or anything that gave me a sign of a hardware problem but I couldn't see anything.

Do you know if I should be checking somewhere in specific?

I also already disconnected and connected back the lights. I was hoping this was a calibration problem with the battery after the update.

[geekmaster]

Is it a random flicker, or a periodic flicker?

[Griu]

Originally Posted by geekmaster

Is it a random flicker, or a periodic flicker?

When it started happening it was starting normally almost at any light level. What seemed to triggered it at first was going on MAX in the light settings. It fixed itself after I turn off the screen for a while and set it on a lower setting.

I forgot about the issue since I usually left it fixed on 15, but I went outside and made the mistake of going to MAX again. After that it got worst, and now every time I go past ten or so it starts flickering.

So to answer your question, no, it's not random.

[knc1]

Originally Posted by Griu

When it started happening it was starting normally almost at any light level. What seemed to triggered it at first was going on MAX in the light settings. It fixed itself after I turn off the screen for a while and set it on a lower setting.

I forgot about the issue since I usually left it fixed on 15, but I went outside and made the mistake of going to MAX again. After that it got worst, and now every time I go past ten or so it starts flickering.

So to answer your question, no, it's not random.

Now that makes it sound like a hardware failure (or hardware in the process of failing).

The 'random' was a different aspect of the problem than what you answered (the pattern of the blinking, not the pattern to the start of the problem) -
but we get the idea just the same.
It was the additional details that helped.

[Griu]

Originally Posted by knc1

Now that makes it sound like a hardware failure (or hardware in the process of failing).

The 'random' was a different aspect of the problem than what you answered (the pattern of the blinking, not the pattern to the start of the problem) -
but we get the idea just the same.
It was the additional details that helped.

That's what I was afraid of. I guess at some point I'll just have a basic kindle.

Thank you both for your replies.

[geekmaster]

Originally Posted by Griu

That's what I was afraid of. I guess at some point I'll just have a basic kindle.

Thank you both for your replies.

The frontlight LEDs are still good. The RIGHT way to fix it would be to use an oscilloscope and track the flicker back to its source. If the frontlight PWM driver chip(s) are dieing, I would power my LEDs with a variable resistor (and series switch) directly off the battery (old-school style), if I could not replace the defective parts. How are your hardware hacking skills?

[knc1]

If the PWM driver chip uses an external capacitor -
then it might be a poor solder connection on that capacitor.

But you can bet that since the cap is almost too small to see, visually inspecting the solder joints will be a waste of time.

Ah, the random question - -
If it is a poor solder joint on something, it should flicker in response to tapping (or even just movement) of the Kindle.
That would look like "random" flickering.

Back in the days before all of the really good CFC's where outlawed -
You could get a spray can of 'part freezer' stuff -
spray a suspected part or solder joint with it, see if the sudden change in temperature made a difference.

There **should** be an equivalent 'freeze it' tool now, but I don't know what it might be named.

[Griu]

Originally Posted by geekmaster

The frontlight LEDs are still good. The RIGHT way to fix it would be to use an oscilloscope and track the flicker back to its source. If the frontlight PWM driver chip(s) are dieing, I would power my LEDs with a variable resistor (and series switch) directly off the battery (old-school style), if I could not replace the defective parts. How are your hardware hacking skills?

I'm not really good with hacking hardware. I've already bought a new Kobo Glo HD (I was planning on doing it before, easier configure the way I want). I'll sell this one and get some money back. I already have a buyer.

[Griu]

Originally Posted by knc1

If the PWM driver chip uses an external capacitor -
then it might be a poor solder connection on that capacitor.

But you can bet that since the cap is almost too small to see, visually inspecting the solder joints will be a waste of time.

Ah, the random question - -
If it is a poor solder joint on something, it should flicker in response to tapping (or even just movement) of the Kindle.
That would look like "random" flickering.

Back in the days before all of the really good CFC's where outlawed -
You could get a spray can of 'part freezer' stuff -
spray a suspected part or solder joint with it, see if the sudden change in temperature made a difference.

There **should** be an equivalent 'freeze it' tool now, but I don't know what it might be named.

Yeah it's not random. Happens no matter what.

I'll check what you mentioned, but at this point I'm pretty much resigned.

Thanks.

[knc1]

Originally Posted by Griu

Yeah it's not random. Happens no matter what.

I'll check what you mentioned, but at this point I'm pretty much resigned.

Thanks.

This stuff (or a product like it):
https://www.amazon.com/Professional-.../dp/B000Z99ZCA

[geekmaster]

If the flickering is periodic (not random) it could be an aliasing effect from an undesired frequency getting into the circuit and "ring modulating" the PWM (brightness) frequency giving the "beat frequency" flickering you describe. Also possible (but unlikely) that there could be some weird "relaxation oscillator" effect if there are some transistors in the circuit that are misbehaving. Or perhaps your kindle is possessed, and just needs a simple exorcism?

[geekmaster]

Originally Posted by knc1

This stuff (or a product like it):
https://www.amazon.com/Professional-.../dp/B000Z99ZCA

Simple "canned air" (air duster) works too, if you hold it upside down to spray liquid propellant instead of air. Plus you can buy it at local office supply stores.

[geekmaster]

Originally Posted by Griu

Yeah it's not random. Happens no matter what.

I'll check what you mentioned, but at this point I'm pretty much resigned.

Thanks.

I think you did not get knc1's (or my) concept of "random". We mean an APERIODIC flicker, not a "random chance of occurance". We are talking about the appearance of the flicker (short time scale), not about its existence (longer time scale).

Random (aperiodic) flicker is likely a cracked or poor electrical connection (and as knc1 mentioned, would probably be affected by vibration). Periodic flicker (i.e. a fast regular blink) would more likely be caused by failing components as I described in a previous post. Failing components might be allowing a local radio station carrier frequency to ring-modulate your frontpanel LEDs, for example. An oscilloscope would help diagnose what is going on, while freezing components (as knc1 suggested) may help locate the specific failing device.