Beeps on charging

[obsession613]

My T42 screen blinks in time with a regular beep when on ac power. This stops when I unplug the power lead. The battery maximiser wizard always shows ac even when it's running on battery with the power lead unplugged. Anyone know why this is?
System board is FRU 3PT5448.

[poshgeordie]

Welcome to the forums and what a weird problem!

The first place to look at is the AC adapter:

• Is it a genuine IBM one, or one of those eBay Asian 'specials'? (see 'Theory' below)

• Does it have a three pin mains lead (with an earth), or a two pin (no earth) lead?
  You should be using an AC adapter with the 3 pin mains lead rather than two pin non-earth wire adapters - see 'Theory' heading below for more information.
  There are exceptions to this - typically the Kensington range has only two pin mains lead, but they get round the problem through clever design and they aren't cheap - I'm using one on this T30 to type this!

The other thing I'm wondering about is whether the AC adapter is 'maxing out' current-wise i.e it's unable to give out the current being demanded by the TP.
This could be when the battery is wanting to be charged and the adapter is simply unable to give the current required and just max's out with no reservoir left to run other parts of the TP.

I mention this because I recently received a TP for repair from someone who'd bought it from a 'reputable' UK eBayer (actually anything but) and they had sold it with a tiny AC adpter which was so underrated current-wise that the battery would hardly charge, and the TP just about managed to run.

Next question - what happens if you remove the battery? Does the beep / screen blank stop?
If 'yes':
When charging could the battery be drawing too much current and is causing the AC adapter to temporarily shut down for an instant; when it shuts down the TP will immediately switch to battery mode until a moment later when the AC adapter starts up again and it switches back to running on AC.
Note that the switch from DC to AC will produce a beep.

Could the problem actually be the battery itself, maybe a faulty voltage management circuit within the battery, or faulty cells?

I would suggest the following steps:

Try another AC adapter but make sure it's a genuine IBM model with the 3 pin mains lead (or (other reputable manufacturer) and has the thicker DC lead.
Remove the battery to see what happens then.
Try another battery and see what happens then.

You may not have another AC adapter or battery to try. I'm prepared to lend you both items - I would ask for a returnable deposit if you don't mind since I'd be taking them off a TP which I'm about to sell - PM me if interested.

Switch Mode AC Adapter Theory:

AC adapters for TP's need to supply stable +16V Direct current (DC) at very high currents.
A conventional power supply would be the size of a biscuit tin and weigh a ton.

There is however a great technology called Swith Mode (SM) which shrinks the power supply size, whilst supplying the necessary current.

The DC output of an SM power supply (SMPS) output is actually an Alternating Current (AC) voltage which switches very rapidly (around 20kHz or 20,000 times a second) between 0V and 16V thus providing a pseudo DC output.

A big downside of this switching AC is that it produces bucket loads of interference which radiates like a transmitter. A poorly designed SMPS can be easily picked up on a radio in the same room as a horrible noise.
One effect on laptops generally is that the touchpad doesn't work properly, or even at all.

A well designed SM AC adapter should have a mains lead with an earth wire - a three pin mains lead in other words; it may even be screened (shielded) as well.
Also it will also have a heavily screened DC lead to the laptop (this lead tends to be quite stiff).
Internally there will be metal shields and good output circuit filtering to smooth the high frequency 'AC' into something approaching good quality smooth DC.

eBay Asian 'specials' are made down to a price and often have no mains earth or shielding, nor I suspect much in the way of DC output filtering.

Hence a good SM AC adapter is more expensive than an Asian Special, but will pay for itself from the first second you start using it.

As I've mentioned above, the Kensington SMPS range uses a 2 pin mains lead; they achieve this no interference and clean DC output through great design but you do pay for it; they work well with TP's (I'm typing this on my T30 with a Kensington AC adapter), and I would imagine most other laptops too.

<EDIT> Spelling and clarified a couple of points

[killer]

Thanks, Nick, for a wonderfully informative posting. I must say I have learnt a thing or two, even though I am not directly affected.

[sktn77a]

Nick:

I think your diagnosis is right up there at the top of the list and I agree that removing the battery would be an interesting experiment (however, without the current draw to charge the battery, a marginal PS might be OK at running the computer). I think you're being a little hard on SMPS, though. Here in the US, we use SMPS on some pretty sensitive equipment and, if its well designed, we have no problems with 2 lead standard power cables. The key here is "well designed" - a crappy power supply can give all kinds of problems even with a grounded power cable.

Hopefully, this is a PS problem and nothing more expensive.

[poshgeordie]

You're right there Keith - SMPSU's are one of the best electronic 'inventions' ever and like yourself I've used in some V sensitive equipment.
The well designed ones are superb, but it's so easy to manufacture rubbish and sneak it into our countries via the grey market.

Why I'm mentioning their 'downside' is that I have a couple of those eBay 'Asian specials' here which wouldn't pass any EMC tests with the wind behind them going down hill.....
They also caused a certain amount of consternation when I first found they stopped the touchpads from working.

One of the best jobs I had was specialist EMC testing which included PC's and laptops, and you would not believe how bad some of them were in that respect; so yup you're right - I do have a rather jaded (cynical?) view on such things!!

[obsession613]

Thanks Nick for such a comprehensive reply.
We have three thinkpads in the house, 2 T42, (1 nearly new and mine) and 1 T23.
I swapped the brick for a genuine IBM one. It did make a significant difference.
With the battery in but no brick connected:
The pulsing screen stopped. No beeping.
With the battery out:
It still flickers when I open up additional programs or screens.
With the battery in and the IBM brick connected:
Regular flicker/screen pulse every 5 seconds.
Flickering when opening additional programs.

The battery maximiser wizard still says AC when on battery.
Installed Win2000 on a spare drive. Still not showing the correct icon.
Laptop battery will only charge up when the laptop is not running.
The motherboard in mine is FRU:39T5448

On the Kingston charger front which particular model do you recommend?
Thanks for your time trying to help. Mick.

[poshgeordie]

Hi Mick - reading through your reply and you say changing the adapter makes a significant difference - do you mean it doesn't make a significant difference?
Can't quite see what's changed from your original post - (hey you are replying to a Geordie ya know!!)

Seriously, it doesn't sound like an adapter problem.

Just to summarise:

On Battery only:
Works fine.

On AC Adapter:
Battery removed: Flickering when opening programs but not regular pulsing.
Battery fitted: Regular 5 second pulsing, also flickering when programs are opened.

It does this no matter what AC adapter you use.
Does the non IBM adapter works OK on the other TP's?

if this is the case then it points to a circuit fault somewhere on the motherboard.

Someone else got any other ideas?

Re the Kensington adapter, it's a 33197, but note that it's one of those multivoltage ones for use with different laptops and is rated at 120W - not particularly cheap.

Minimum spec is 16V 90W (5.6A); I think some of the smaller TP's can use 60W ones, but this is too small for the T4x's

I'm sending you a PM Mick

[obsession613]

Thanks for your ongoing support. I have used all the chargers in our house on this T42, it is better with the IBM one but not right.
All the bricks, IBM and cheapo Asian ones power my daughters T42 and charge the battery while the computer is in use, so adapter is not the main issue.
The computer is a conglomeration of parts.The Lenovo site shows a different part number for the motherboard when I enter the serial number on the case in the part finder search so I presume this has been replaced at some time. When I got it the screen arrived smashed so I fitted a T41 complete screen assembly. Having got it going I noticed this flickering problem and the switching of the icons from battery to AC all the time. I carefully disassembled the laptop and checked everything I could for dodgy connections. The only loose thing I could see was the power adapter socket, no screw in it to hold it in place, so I fitted a new screw to secure it and checked the connections with an ohm meter. The connector is a good fit in the motherboard. I left the computer on charge all last night and it didn't fully charge the battery (known to be good as tested in other T42). When I went to disconnect the AC plug the screen flickered wildly, the icon flashing between battery and ac. Do you think this points to a circuit problem on the motherboard in the power supply area, perhaps a dry joint or something.

Thanks again, Mick.

[poshgeordie]

Sounds like a classic DC connector problem - the innards go slack with time.
Check your PM's

[obsession613]

I've just stripped out and checked the power socket and especially the -ve side connector which is holding the power jack very tightly. My ohm meter checks don't show any loose connections in the socket and I cannot create a connection problem with the socket out of the machine, but are you suggesting I try replacing the socket with a new one first?
If it's just the power socket why would the wizard icon in the taskbar never show battery when it's on battery only? The flickering also causes the brightness bar to come on and off as well.
Thanks again, Mick.

[poshgeordie]

I take your point there Mick - there are these other issues with the battery indicator and so on, but that could be related to there not being power from the adapter for long enough for it to register - ie if the adapter power's going on and off rapidly(ish) then that could cause all sorts to be happening elsewhere·

Before I send a connector down, on the motherboard can you check the four thick pins on the socket which the DC connector plugs into, are all soldered to the board - ie not damaged or torn off. From there you have the main fuse F2 at the end of the legs...and we're back to a faulty motherboard

Plug the AC adapter lead into the DC socket and gently pull the lead to one side to 'anchor' the plug in the connector. Check on the meter that you've got solid + - 16V on the thick pins on the board socket regardless of any pulsing / flickering you're getting elsewhere.
Assuming your ohm meter also does DC volts too; also only check if you're OK doing that sort of thing, don't want to cause more damage.

What then happens if you try tapping the board with an insulated object - anything?

It's got to be either the DC connector or the board.....maybe!

[obsession613]

Checked the four pins on the surface of the board in front of the connector from the socket. 0,0,16.5,16.5 regardless of what I do with the jack (wiggling it about). I will fit replacement board as soon as it arrives and despatch old one for diagnosis of problem.
Cheers.

[obsession613]

Replacement motherboard arrived Sat am and fitting it resolved all the issues with flickering screen and the battery wizard icon misreporting. I did encounter a blue screen error even after a format and reinstall relating to ati2dvag.dll. See my separate post entitled ati2dvag.dll error for a fix which worked for me.
A big thank you to all who offered their help, particularly Nick Paton at Reflow Repairs for going the extra mile with this one. Faulty board is in the post for diagnosis of the problem, if a repairable cause is found will post it on here.
Mick L