Blinking LCD problem on T43

[Pawelek]

Hi

Recently I've asked a few qestions around here, but I do have some problems with my t43. Here is the latest one: LCD blinking. It makes completely dark for a second or two/three and then it works okey. Sometimes it takes place one time after another, sometimes only once or twice during my notebook usage (frequency is random). My investigation has shown that the issuse may be power supply (not the AC Adaptor itself - checekd on another T40 AC [same parameters, blinking occured]). Simlpy when this happens for a longer time I can see the battery icon instead of AC plug icon. As you know blinking occurs (and I guess it is normal) when the power source is changed (battery or AC). How can I solve the problem? Is it harmful? Will this problem become more frequent in the future? Or maybe I should not warry about that. Please help, and share your opinions.

[poshgeordie]

Hi Pawalek

I started replying with a whole lot of "check the display" type of answers, but on reading your description, it sounds more like a component problem.

What happens if you remove the battery and run it just on the AC Adapter?

What happens if you run it just on the battery?

[Pawelek]

First of all I want to thank you poshgeordie for your reply. The answers for your questions sound:
1 -> dont know since I havent tried such option yet - I'll check it tomorrow
2 -> Havent seen blinking when running on battery

Can you explain what you mean about component problem. I'm not a hardware noob but I dont get it

[poshgeordie]

Hi again

By 'component' I mean one of the actual electronic pieces on the motherboard, like a resistor or transistor or integrated circuit (IC) chip.

Let us know how you get on with the tests I suggested.

[Pawelek]

After testing my notebook only on AC (the battery was unplugged) I can say that there is no blinking problem. Summerizing it can be stated that blinking occurs only when battery and AC power are both plugged. The frequency off this problem is random. Is there something relatively easy and in good value of money I can do to solve this situation?
Thanks in advance

[poshgeordie]

So it works fine if it's only on the AC adapter with the battery removed. Does it also work OK if the AC adapter's removed and it's only on the Battery?

I see that you say it doesn't work if both the AC adapter AND the battery are connected at the same time.

If you connect the T43 to an external monitor using the VGA connector at the top right hand corner of the T43, does the external display blink in the same way as the T43 display did?

We need to check that the problem is not caused by a faulty AC Adapter.

What is the current rating / wattage rating of the AC Adapter? You should be using at least a 16V 4.5A / 72W model.
If the adapter is a lower specification then the T43 may be 'asking' for more current (amps) than the adapter can give and is then switching off. It then recovers again and starts up again and this may cause the display to blink.

Does the T43 beep when the screen goes blank, or goes from blank to OK?
If it does, this could be due to the AC adapter voltages turning off and then on again. The beep sounds when the T43 changes from AC Adapter voltage to the internal battery and back again.
Again the AC adapter may be faulty.

Both the faults above may also be because of a faulty component (Wadliwy elektroniczny składnik) on the T43 and is much more difficult to say what is the problem.

[Pawelek]

I can say it works OK on battery only too. The problem can be reported only on battery and AC both plugged. I can hear no beeping as I turned this feature in BIOS. I'll reenable it and make some further testing. I guess the AC parameters are fine. Numbers are the same you stated above. I've also used another AC (16V, 4.5A) from T40 and blinking occured. Unfortunately Im afraid this is some ciricuit on motherboard or other component. If this issue stays on the present level I can stand it, but I wouldnt like it to occure more frequent in the future

[poshgeordie]

The problem's got to be something in the battery charging circuit on the motherboard.

The reason for this is that you've proved that the circuits work OK when on either AC or Battery only.

The problem occurs when both are connected, and then the only extra components are those which charge the battery.

This post has a link to a diagram of the battery charging circuit which may help.

I suggest you run your laptop from either battery or AC, and then charge the battery from the AC adapter when the laptop's not being used - in hybernation with the lid closed.

[Pawelek]

I've enabled beeping in BIOS when changing power source and what is werid beeping sound isnt hearable when the screen is blinking and AC turns into battery and back. Only when I physically plug off or plugn in the AC computer beeps. Tried to gather some info about new motherboard and it is prized about 620$ (1.7 times more expensive than my notebook ).

[poshgeordie]

As I said in an earlier post, run the Thinkpad either on AC Adapter with the battery removed, or on battery only. Recharge the battery when the laptop is turned off but the AC Adapter plugged in - say overnight or whilst you are at work etc.

Regarding the motherboard could you post the FRU number. I recently bought a good board with the Intel graphics chip for a lot less than $620 from this ebay store and found them very reliable and extremely quick as well.

[Pawelek]

I was said to check some part number at the bottom of notebook under the second RAM socket. The number is 42T0069

[poshgeordie]

On UK eBay there's this onefor only £79.99 free shipping within UK.

Details on the eBay seller here

And this one from the eBay shop link I sent you earlier - refurbished for $260 inc carriage.