Ibm Thinkpad t42p will not turn on

[aouate3]

Hello, First let me start by saying that i have quite a bit of technical knowledge, i know my way around motherboards, repairing electronics, and soldering.

Well i have a clients ibm thinkpad laptop, it is a T42p laptop, it will not power on, and it will not illuminate any L.E.D.s on the status bar, the charger is good. The Charger port is good, fan is good, harddrive good, ram good.

He told me that a couple days before it died he experineced a "Power Surge On Usb Hub" alert and he didnt have any usb devices connected and the laptop is not equiped with a webcam or a built in bio-metric reader.

It is apperent that there is a short somewhere on the board because if i take the motherboard and connect the charger, something in the region of the inductors makes a meep meep meep noise, similar to the sound you hear if you take a dell or gateway charger and short it out.

At first i thought usb, and my multimeter found something odd, if i set it to continuity and put a probe to the Positive pin on the usb and then tapped the other probe to the motherboards common ground (screw hole plating) the multimeter beeps, which would make sense because of the usb power surge so i unsoldered the usb fuse on the positive lead.

I tried to power on the motherboard.. still nothing and still the meep meep meep, so i resolded the usb fuse..

i checked the dock connector and it looks fine..

does anyone have any ideas?

[ajkula66]

Welcome to the forum!

USB failure equals bad Southbridge chip which has obviously pulled something else along with it while going down...

Long story short, you need a new board.

Good luck.

[aouate3]

well im not so sure, the charger also makes the meep meep meep exactly at the same time the mobo does, i have tried several chargers, also the dock port on the bottom of the mobo, the four pins, they also put out power in pulses, also the inductors get hot, it seems there may be a short, but that could be from the southbridge "traveling" due to becoming unsoldered, which chip on the board is the northbridge and which is the southbridge, i could never figure that out on thinkpads * feels like a noob even though he is often called the future bill gates *

[aouate3]

i figured out which is the southbridge, now you said it may be the problem, how do i confirm this, because there could be other causes.

[Harryc]

The chip that says "Intel" in this picture is a southbridge - http://www.thinkwiki.org/wiki/File:T43p-82801FBM.jpg

[Harryc]

We're not going to get much more in depth here other than to advise putting pressure on the southbridge while powering up. If it's a loose solder connection it may temporarily connect under pressure.

[ajkula66]

Remove all the RAM and try to power the machine on.

Does it beep?

If it does, what sequence does it give?

I'm definitely not new Bill Gates but would still bet on you needing a new board.

Good luck.

[aouate3]

ok, i will attempt this, if it is the southbridge, i know how to fix it... but if someone could confirm that the meep sounds (not from speakers, from the reigon where the ltp port, usb, and inductors are at, next to the intel rc82540EP chip) can be caused by this, that would help, Thanks

[Harryc]

Send a PM to a member here named poshgeordie. He's probably seen more boards with Southbridge problems that all of us put together. He might have seen this symptom. He runs a reballing company in the UK.

[aouate3]

when i press on the southbridge it wont turn on but the dock port puts out power in pulses...so it is unsolded, but since the board still isnt showing any signs of life... wait... maybe i should add that the board is getting kinda hot, around the resistors in the "L" shape on the back, the inductors, the inductor by the ltp port thoose werid midcom chips and there is a chip right next to the main fuse that gets REALLY REALLY hot, it burnt me and thats how i found it, the chip has 8 legs and it looks lik it says I(werid logo)R433m which google didnt pull up anything usefull

Ok, Harryc i will PM poshgeordie..

[poshgeordie]

Hi - thanks for your PM.

I've got to say this is a weird one on me.

The main area of concern is the temperature of those components which does indicate possible excess current, but may be normal. Could you give me the circuit numbers as marked on the board and I'll look into that.

If we received this unit in the workshops then the first thing we'd try is to reball - not reflow - the SB. This is because it's possible a solder ball has become detached and is shorting out something else which may be causing the other chip to warm up.
Also once the SB is removed I'd then run it to see if the chips get warm. OK not very scientific but worth a shot.

The other thing which does occur is how hot does the SB itself get? We've had a couple where it gets very hot from switch on due to a short somewhere (solderballs?). BTW to confirm the SB is at the front of the motheboard under the wifi card holder.

We've been finding more and more that were there is a T4xp or T43, i.e where the GPU has a metal top, then the SB soldering is likely to fail.

Let us know how you get on.

[aouate3]

Do you mean circuit numbers as in the number by the chip or resistor or other overheating SMT device?

[poshgeordie]

Do you mean circuit numbers as in the number by the chip or resistor or other overheating SMT device?

Yes - I'm not in the office right now but there should be letters/numbers printed on the mobo next to the components. I'll then check to see if they're associated with the SB in any way.

However with the original USB error I'd be looking at either shorted solder ball "pins" on the SB or the SB itself which has failed; but that's not to say one of the MOSFET switches (8 pin SMT's) has failed.

[aouate3]

ok, here are the numbers

they all reside in the upper left side of the board (when board is faceing up, otherwise its upper right)

Front Side:

wtf, no numbers...

so ill post the general location and printed number on chip of the overheating parts

IOR433m (to the left of the four pin power connector on the board itself)(gets really hot)
IOR436H (below four pin power connector)
IOR436H (right next to other IOR436H)
The two inductors right by the ram module holder

Back side:

part numbers in some places

C911 the resistors(at least i think there resistors) in the L shape the bottom section of the L that points to the audio jacks is pretty hot

both midcom chips 7219-35


U25 resistor thingy near L by heatsink (gets pretty hot

(also BTW the multichannel temperature sensor thing (MAX1989) is partially unsoldered, i think all the pins are touching, i can make sure of this if u want..)

the inductor and 8 legged chip in the C678 get sorta hot


also oddly enough if i have it plugged in for a little while, more parts start to heat up....

[RealBlackStuff]

That mobo is well on it's merry way to become the toast of the town!

[poshgeordie]

Yeah - tend to agree. Suggest getting a new one.

[aouate3]

well i dont mean to doubt professionals, but i sorta disagree because something shorting out could cause this, most of these parts do handle power regulation do they, and the meeping from the board does mean there is probably a short, but are these parts "wired" to the southbridge... that is the question, if you want, if anyone has pictures of the front and back of the board i can highlight the parts that are overheating, there really all in the same general area....

[ajkula66]

OK, since you obviously know this stuff better than several people who have gutted anywhere from several hundred to a couple of thousand T4x machines each, feel free to post your success story once it finally plays out...

Good luck.

[poshgeordie]

OK, since you obviously know this stuff better than several people who have gutted anywhere from several hundred to a couple of thousand T4x machines each, feel free to post your success story once it finally plays out...

Good luck.

Hey George - I think the guy has a point in a way since I did volunteer to help him and my last reply's not so helpful!!

Having said that it's going to be very difficult to do any meaningful work on your board because of the lack of circuit diagrams.

But lets see what we can do.
Diagram if needed - Got o my sig and download the documents link and from there download the T4x fuses doc which has a couple of good hi res photos if that will help.

Re the components you're referring to, I've got a board on soak so can check the temps.

IOR433m (to the left of the four pin power connector on the board itself)(gets really hot)
IOR436H (below four pin power connector)
IOR436H (right next to other IOR436H)
The two inductors right by the ram module holder

The tw0 436 components are MOSFET switches which do get warm but not hot. They are in the main supply lines which will probably go in the vicinity of the inductors (below) but don't know for sure.

I believe the inductors ( labelled L2 & L7) connect to U21 and U25 respectively on the underside of the board - near U25 etc, They look to be in main supply lines to those devices which may be MOSFET drivers or similar, which both then connect to the little square chip ADP3205 which is a [url=javascript:openreq('http://www.datasheetcatalog.org/datashe ... 05_prk.pdf')]CPU Controller[/url].

C911 the resistors(at least i think there resistors) in the L shape the bottom section of the L that points to the audio jacks is pretty hot
both midcom chips 7219-35
U25 resistor thingy near L by heatsink (gets pretty hot

(also BTW the multichannel temperature sensor thing (MAX1989) is partially unsoldered, i think all the pins are touching, i can make sure of this if u want..)
the inductor and 8 legged chip in the C678 get sorta hot

They're in the same area as the parts above.
The C911 are capacitors and are used to provided filtering / smoothing to the supply lines.

the Max 1989 - my test board isn't fitted with that arrangement so cannot comment but it aught to have all the legs soldered even if some aren't used.

Not sure about the audio jack comps.

V difficult to give any comments as to the fault area, but I would expect U21 and U25 to be the same temps since they both go to the CPU controller chip - maybe a problem with the CPU controller?

I won't be able to help you further since it needs a circuit diagram, so you're kinda on your own but hope what I've given you helps a bit.

[aouate3]

edited out anger post

[poshgeordie]

@ aouate: PM sent

[aouate3]

not worthy to be here

ill get pics as soon as possible

[poshgeordie]

Get up off yer knees and start fault finding!!!

I've just PM'd you since I remember now of some boards with a similar-ish fault, in that they only booted when you pressed down on the top of the board in that area.
I never managed to find what was causing it - tried soldering every component for instance - but I'm becoming more convinced as time goes on that there is another problem area with T4x boards which may have a simple solution.

In my case the board is dead until you press on the board behind the audio connectors (the two big inductors), when it springs into life.
I then narrowed it down to not being a major chip (eg Southbridge) by having the board supported vertically with no stresses on it and gently squeezing both sides. Again the fault narrowed to something to do with the components in the same area you mention.

The CPU Controller is right in this area. In your case, one of the 2 driver chips to the controller becomes warm and the other doesn't.

We could do with more evidence of other users having dead boards which work when you press in this area, and see if we can tie it to your findings as well. Maybe I'll start a new thread to this effect.

I think in all honesty you won't find the fault unless you can replace the Controller chip but it's a very worthwhile exercise nonetheless.

Let us know what you're finding and any ideas etc.

[aouate3]

ill get right to fault finding, maybe i should donate this motherboard to you for expermenting on, if i cant get it working that is..... i had a feeling it probably was not a southbridge problem but at this point idk if its fixable without a reflow or reball of the probably BGA cpu controller

[poshgeordie]

I think the board is only useful for as a source of future spare components - and to practice connector solder skills on as per your PM (answered). I've got tons of "experimenters" so don't really need another but thanks anyway.

If you want a good replacement board from a reliable source, place a Want to Buy in the Forum Marketplace and remember to say which board you need (the number is the FRU on the bottom underneath where the bottom RAM chip lives).
People there will then come back to you with either the exact same board or a good equivalent.

[aouate3]

http://i754.photobucket.com/albums/xx18 ... pad1-1.jpg

http://i754.photobucket.com/albums/xx18 ... nkpad2.jpg

sorry for the crappy pics, i was going to use the really nice pics from poshgeordie T4x fuse pdf, but they had numberings and they werent easily removable

[aouate3]

oh yea, the red dots are on the parts that are heating up, the bigger the dot, the hotter the part, computer still wont power on, even with board slightly flexed or with pressure on the intel chip in the pic (persumably the cpu controller?) i want to find a way to charge the battery, as it is dead, and see if this machine will power up with a charged battery in it, if so somethings wrong with the power regulators i think, but i dont currently have a way to charge the batter, i cant do it the way i do with cell phones, use a 3.8 volt dc adapter and charge the cell. i rather not pop open this battery, its new, its not a lenovo battery i dont think, ill have to check with the owner, maybe a faulty battery killed the laptop?

[poshgeordie]

Thanks for the photos - it's those components as I thought.

You're going to have to remove the photos since you're breaking forum rules (the reason is they need to keep the forum capacity down - I think):

5. IF you must add a photograph to your post, PLEASE limit the size to 50k or less and place a warning in the subject line.

Maybe what's better - as many other member's do - is to post them on a photo site and make a link to them.

Just had a thought - you don't by any chance have another CPU chip? If you have maybe try that.

Re the battery - don't open it up coz those cells are V dangerous if you damage them in any way. I was thinking of doing reconditioned batteries until the time I accidently shorted the positive to the metal case for about half second, and in that time the battery heated up so quickly that I thought I was going to have a fire on my hands.

Read up on Li-ion rechargeable cells for more information.

Also no way of charging it unless you have another board - sorry.

[aouate3]

i have re-"celled" batteries in the past, quite a few of them, just want to watch out for shorting and make sure the battery you are dealing with isnt a "smart battery" or it wont work ever again.usually on a standard battery there are 6 cells, wired up in sets of two which are connected in parrallel. there is a wire coming from each "break point" so there are four wires, which connect the the batterys ICU which handles regulating current, protecting the cells from overheating, battery health, Etc.

yes i do have a couple cpus handy. i used to repair laptops for my middle school. they had over 2,000 laptops, ALL thinkpads, of the 2,000 latops, about 800 of them where deamed DNR (do not repair/recirculate) they were deamed DNR for simple reasons, broken keyboard, missing keys, missing parts, broken screen, the occasional pencil through the screen (only on r51's, easier to get past the shell) violence victims, like the one that was smashed repeatedly, thrown in the air, then milk was dumped on it, and finally, but not least, the occasionly motherboard failure,

i got a good 550 of them fixed by mix matching parts, got them into near perfect condition and back in the circulation for students, the rest were thrown out... i have seen quite a few thinkpads and i hate to see another one become a permenent DNR...

for being only 15, i have seen and repaired quite a few computers, mostly thinkpads, although i do repair tons of computers for my friends, both desktop and laptop, by far my favorite to repair is desktops because of the fact its easier, and u dont get the problem where after u reassemble the machine you have left over screws and you have no idea where the went..

[aouate3]

oh yea, and im pretty sure i mentioned this, but the status L.E.D.s on the screen bezel dont turn on or anything, wont even charge, which is why i think it may be a problem with the laptops charge "delivery system", because the battery is stone dead, im not talking about a moss covered stone, im talking about a clean stone, DEAD. not even a volt being outputed, my multimeter picked up .12 on the voltage test, setting was at 20, so it is on the right setting, and thats the right reading, its the reading from the CELLS, not from the ICU