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PostPosted: Fri Feb 27, 2009 10:01 pm 
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I just put together a nice T42 that works great except for the problem in the subject line. I've tried several batteries and chargers known to be good. All of them discharge but won't recharge. The Battery Information applet indicates that voltage is OK but current is zero. All the software and drivers are fresh installs. It's running XP pro witth 1GB RAM. Is this likely a fuse problem? If so, which one? Other ideas? Thanks!

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 Post subject: fuse key??
PostPosted: Fri Feb 27, 2009 11:00 pm 
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I'm an idiot for not doing a better search. There's so much info here, it's amazing! Anyway, I'm now checking fuses. The fuse pictures are great - but does anybody have a key to what they do?

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PostPosted: Sat Feb 28, 2009 8:19 am 
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hi,

if you have still problem give me pm (i have some parts)

i replace 3 compoets:
adp3806, two integrated mosfets and 1 resistor.

cheers

my link
http://forum.thinkpads.com/viewtopic.php?f=2&t=70832&start=0

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T23, T40, T43p, T43p, T61p

Total solution for absolutely ZERO oscillatory noise in t4x - 100% working
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 Post subject: Re: fuse key??
PostPosted: Sat Feb 28, 2009 10:45 am 
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Location: Pound Ridge, NY
Thanks for the offer, I'll let you know if I need anything. But I have a couple stripped T42 boards laying around, so I'll start with those.

Then there's this:
raueda1 wrote:
I'm an idiot for not doing a better search.

As penance for my idiocy I offer a nice video I found on soldering SMD devices:
http://www.youtube.com/watch?v=3NN7UGWYmBY&feature=related :bow:

Although I've done a lot of soldering I've never messed with SMD's. I think the video will save me a lot of time fiddling around to get it right.

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IBM T42p 2373-WBB, 2gb, 7200 rpm HD
IBM X31 2885-PWU, 2gb, 7200 rpm HD
ThinkPad T40 2379-
ThinkPad T20 2647-4AU
ThinkPad 390X


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PostPosted: Sat Feb 28, 2009 3:40 pm 
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AdaSch wrote:
hi,
if you have still problem give me pm (i have some parts)

i replace 3 compoets:
adp3806, two integrated mosfets and 1 resistor.

cheers my link
http://forum.thinkpads.com/viewtopic.php?f=2&t=70832&start=0


thanks very much for the suggestions. Unfortunatley All my fuses test OK:?

I'll try your suggestion on the 3 components. Here are a couple comments;

1. The location of the adp3806 is obvious. Shouldn't be an issue to stick in a new one.

2. The mosfets are directly under j13, correct?

2. Where exactly is the 10ohm resistor?

Thanks for the excellent advice. I'll post my results.

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IBM T42p 2373-WBB, 2gb, 7200 rpm HD
IBM X31 2885-PWU, 2gb, 7200 rpm HD
ThinkPad T40 2379-
ThinkPad T20 2647-4AU
ThinkPad 390X


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PostPosted: Sat Feb 28, 2009 4:05 pm 
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I would also look at any of the inductors around the area of the ADP3806. In my experience with the T23, a loose inductor will exhibit these same symptoms (lack of charging). I don't know if the T4x systems have the same type of issue with these parts but it can't hurt to poke around and see if you can lift up one side of the inductor(s).

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PostPosted: Sat Feb 28, 2009 7:10 pm 
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raueda1 wrote:

thanks very much for the suggestions. Unfortunatley All my fuses test OK:?

I'll try your suggestion on the 3 components. Here are a couple comments;

1. The location of the adp3806 is obvious. Shouldn't be an issue to stick in a new one.

2. The mosfets are directly under j13, correct?

2. Where exactly is the 10ohm resistor?

Thanks for the excellent advice. I'll post my results.


ad1, adp3806 12.5 is absolete. I work in ems compamy and i search this 3 months! (10 pcs buy)

ad2 no, mosfet is underboard, near large coil

ad3 near 24 leg adp3806 . 10ohm is connected to 1 leg.


manual how to check why this won't charge:

how to check adp?

if you work on battery and you see power consumption probably adp is good

where is problem?

1 check volage on 1 leg adp. If is near 16v resistor is ok or if near 12v resistor is broken
2 check voltage on 24 leg when power is on and ond off. in first case shold be more voltage vs second case. if not, check voltage on 22 leg if is near 5v (when on ac) yor mosfet die.
http://www.fairchildsemi.com/ds/FD/FDS6990A.pdf - this is mosfet in t43p (i have 9 pcs)

cheers

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PostPosted: Mon Mar 16, 2009 4:21 am 
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Location: Bucharest, RO
Hello, I have a similar problem with a T40 mobo: runs fine on a charged batery, reads everything from battery (manufacturing date, id, serial no, charge cycles), shows voltage and power consumption, but when I connect the charger it reads only bat voltage and a 0.00A charging current. The laptop senses the charger being connected or not by making beeps and adjusting screen brightness.
I measured voltages on ADP3806 and all looks fine. The problem seems to be with the most right TPC8014 transistor (before F12) in the diagram ( http://dbhome.dk/sma/t41/t41_block_01_v1.1.pdf - Thanks SMA).
The voltage after the inductor of charging circuit and also on Drain pin of TPC8014 is 12.5V . Its Source pin has the battery voltage and logically the transistor should close in order to charge the battery. I measured its Gate voltage with a multimeter and the voltage is 0.2V with charger conected and 0V with it disconnected. The low voltage makes me think it is a PWM signal, but I'm not sure cause I don't have a scope ( the Gate pin is connected to the Toshiba chip below the wifi card through a 100k resistor).
In case the voltage I measured is ok, then the mos transistor must be changed, otherwise the toshiba chip is broken, or some other problem.
Does anybody have the possibility to measure this transistor on a board with a good charging circuit? Or any other advices?

Thanks


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PostPosted: Mon Mar 16, 2009 6:07 am 
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calinp wrote:
the Gate pin is connected to the Toshiba chip below the wifi card through a 100k resistor).

Thanks


Are you sure? Your laptop work on battery. When this chip be broken, t4x should go off when on battery.

You can always connect battery to second connector. Its possible after disassembling mobo (i did it :) )

check TPC8203/1. Yo can doo shortcut between D and S. When charge start, you found broken chip.

cheers

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T23, T40, T43p, T43p, T61p

Total solution for absolutely ZERO oscillatory noise in t4x - 100% working
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PostPosted: Mon Mar 16, 2009 6:22 am 
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Location: Bucharest, RO
Hello AdaSch,

"Are you sure? Your laptop work on battery. When this chip be broken, t4x should go off when on battery." Are you reffering to mosfet or toshiba controller?
The parasitic diode of the mosfet is ok, so, on battery, no matter what voltage is on gate, the current will still flow through the diode (from battery to Source of TPC8111)

The mobo is diassembled :) and I will try tonight to connect the battery to the second connector.

Shorting TPC8203/1 may not be a good ideea because there are 12.5 volts before and after the FET 57LAA, which means the switching regulator is fine.


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PostPosted: Mon Mar 16, 2009 12:11 pm 
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Posts: 93
Location: Austin, Texas
Check the DC input power jack. Those seem to fail fairly often on TP's. I think mode of failure is that they come loose from the motherboard.


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PostPosted: Tue Mar 17, 2009 6:57 am 
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Location: Bucharest, RO
DC jack is fine. I replaced TPC8014 but I had the same problem. Finally i shorted that transitor and charging seems normal (I have now current and power readings). I'm still testing this solution because I'm sure I deactivated some kind of protection :)


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PostPosted: Fri Nov 04, 2011 2:43 am 
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Location: San Francisco, CA
Hello - I stumbled across this post and was happy to see it's relatively recent. Hoping to get some help with the same problem...

I have a T41P. Originally the battery would not charge and the battery status light would constantly flash amber while plugged into AC. The battery would never get charged - 0%. I received a new battery today and placed it into the machine. With the new battery, while powered off and AC plugged in, the battery light was a solid amber so I thought "good sign". I let it charge over night but was surprised the next day the battery was still amber. I powered the system up and the battery tool displayed a 53% charge. Upon removing the AC, the percentage went down, however, plugging in the AC wouldn't charge the battery.

I've disassembled the unit and checked the fuses found in this link: http://nickpaton.fireflyinternet.co.uk/ ... 0Fuses.pdf but none of them seem to be blown. I'm obviously missing something but not sure where to go from here.

If it helps - I know my son had plugged a power adapter from another Lenovo (Netbook S10) into my T41p. I think the netbook AC is a little higher rating than the T41p so that may have triggered the issue.

Please help...

EDIT: A couple of more observations to add...

1.) When first plugging into AC with the battery connected - I get 9 blinks from the battery led before going to a solid amber
2.) Having the unit in a port replicator also produces the same results (battery doesn't charge)


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PostPosted: Fri Nov 04, 2011 12:18 pm 
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S10 adapter supplies 19V. Connecting that to a T4x will definitely blow some motherboard components. (T4x only needs 16V).

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PostPosted: Fri Nov 04, 2011 4:00 pm 
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Location: San Francisco, CA
Yeah - I kind of figured it was blown. The first "original" battery is shot too since it constantly flashes amber and won't charge in any other machine. The new battery, however, flashes 9 times in succession when the unit is first powered up and then goes steady amber leading me to think it was charging but no dice.

Soooooo.... that said. I'm trying to sort out how to fix it or if I should just get a different system. I'm seeing T61's ranging from $150 to $250 and T400's not too much above that. I guess I can say goodbye to my old friend and get something faster. I just like to fix stuff but am afraid this wouldn't be worth the effort.

That said - anyone looking for a perfectly good T41p? For Free????? Perfectly good except for the charging problem... ;)

Hell - I just got a new battery and 1GB add'l RAM upgrade for it too!!! (Hence my reluctance to "let go" so easily.


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PostPosted: Fri Nov 04, 2011 8:57 pm 
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Already have a few PM's so the T42 has found a new home... Just a quick note to update the status.

Cheers!


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PostPosted: Fri Jan 20, 2012 5:16 am 
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Joined: Fri Jan 20, 2012 4:45 am
Posts: 5
Location: Latvia, Riga
I got T42 with problem, described in subj. Here is the picture after taking a look on mainboard:
http://content6-foto.inbox.lv/albums183 ... as/t42.jpg
Can You help me with information, what is written on chip (marked as Q4), I will try to change it myself. And how do You think, will it be enough?
No problems with working on battery or from AC. Charge indicator blinks.
+++++++++++++++++
Update:
Seems it is FDS6990A.
If You have any comments - welcome..


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PostPosted: Sat Jan 21, 2012 2:12 am 
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Welcome to thinkpads.com!

FDS6990A is a Dual N-Channel MOSFET (metal-oxide semiconductor field-effect transistor); basically a high power switching transistor. It's "dual" in that is has two separate MOSFETs inside the same package. Most of the 8 leaded ICs with that package style are some type of MOSFET. That it has erupted and let the "magic smoke" out usually means that there was (or still is) a short somewhere on the motherboard. You could try replacing it with a new unit but you may also end up destroying it.

The usual method to replace something like this would be to cut all eight legs off the IC right along the edge of the plastic package. You then apply a low-wattage soldering iron (around 25W or so) to each leg, one-at-a-time, and remove them from the board. Clean up the metal pads on the board with solder braid and solder on the replacement. Use the thinnest solder you can; somewhere around 28 gauge, as that will reduce the chances of shorting the legs.

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PostPosted: Sun Jan 22, 2012 4:52 pm 
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Location: Latvia, Riga
I changed FDS6990 with alternative (more powerful) F7832 and now it is impossible to start laptop at all.
http://content22-foto.inbox.lv/albums18 ... /F7832.jpg
When power from 16V adapter is supplied, oscillator shows short (small part of second) and regular (cycle is about 1 sec) power jumps from 0 to 16V. Seems, that some internal protection is working. If battery is connected, power on battery contacts is zero.


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PostPosted: Thu Feb 09, 2012 6:58 pm 
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When I removed chip at all, power was 16V and laptop starts. Any ideas, where to dig? Can You confirm, that original chip is FDS6990?


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PostPosted: Fri Feb 10, 2012 3:12 am 
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Yes, I can confirm that Q4 is FDS6990A. It's a MOSFET that is connected to the ADP3806 battery charger controller. I would have replaced it with an identical unit, not anything more "powerful", unless you know more about circuit design than the original developers. My guess is that there's still a short somewhere on your motherboard. That would be one good reason why the part blew up in the first place. Unless you can find and remove that short, you would probably be better off changing the entire motherboard.

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[DONOR] X22;X24;X31;X41;X41T;X60;X60s;X61;X61s;X200s;X300;X301;Z60m;Z61t;Z61p;560Z;600;600E;600X;T21;T22;T23;T41;R50;A21p;A22p;A31;A31p
NOTE: All links to PC-Doctor software hosted by me are dead. Files removed 8/28/12 by manufacturer's demand.


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PostPosted: Fri Feb 10, 2012 3:49 am 
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Location: Latvia, Riga
Thanks for Your answer! More powerful in this case means more current (A) resistant. But yes, You may be are right:) Could You suggest, where to find as possible detatailed T42 charging circuit schema for easiest way to find short?


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PostPosted: Fri Feb 10, 2012 7:11 am 
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This is the charging diagram from an otherwise identical T41: http://dbhome.dk/sma/t41/t41_block_01_v1.1.pdf

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Check out The Board Room for:
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- other Services


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PostPosted: Fri Feb 10, 2012 9:04 am 
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Location: Latvia, Riga
Thanks "Thinkpad User", who sent me T42 planar schematic by e-mail and RealBlackStuff posted picture (seen before in this tread)! I will try to resolve this problem :>


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