T42p charger not recognized

[sbjoe]

Subject line pretty well sums it up. I've not done anything out of the ordinary like trying to charge it with anything other than the factory supplied unit which shows 16.5Vdc when plugged into the wall outlet. I've tried two batteries and both are nearly completely depleted of charge at present. Is the first step removing the mb and looking at the fuses? Presumably there will be visual evidence if one or more is blown...? Don't know that there's enough charge left in either battery to complete the boot process. Are there other likely causes? Thx,

[rkawakami]

If you are measuring the proper 16VDC level at the plug, then most likely there's enough current to power the laptop and charge the battery. That leaves the motherboard to be the source of the problem. Most of the surface mount fuses cannot be verified visually; there's only a few that have a clear body so you can see the fusible link. Luckily, the fuse protecting the DC input is one of those but you will probably need a magnifying glass. If you can't see it clearly, then you can test for continuity (0 ohms) with your meter.

You can find a handy fuse map for the T4x systems here: http://forum.thinkpads.com/viewtopic.ph ... 39#p686839

Fuse F2 is the one that is inline with the DC input. If that one is blown, then no power via the AC adapter. Your problem may also be in one of the power transistors. Some of them can start glowing like a neon lamp and after that, they tend to let the magic smoke out of the plastic package. If that happened, most likely you would have been able to detect it with your nose.

(edited for clarity/typos; so much for trying to type fast without re-reading it )

[sbjoe]

If you are measuring the proper 16VDC level at the plug, then most likely there's enough current to power the laptop and charge the battery. That leaves the motherboard to be the source of the problem. Most of the surface mount fuses cannot be verified visually; there's only a few that have a clear body so you can see the fusible link. Lucky, the fuse protecting the DC input is one of those but you will probably need a magnifying glass. If you can see it clearly, then you can test for continuity (0 ohms) with your meter.

You can find a handy fuse map for the T4x systems here: http://forum.thinkpads.com/viewtopic.ph ... 39#p686839

Fuse F2 is the one that is inline with the DC input. If that one is blown, then no power. Your problem may also be in one of the power transistors. Some of them can start glowing like a neon lamp and after that, they tend to let the magic smoke out of the plastic package. If that happened, most likely you would have been able to detect it with your nose.

Thanks Ray, I had downloaded the fuse map a good while ago; fuse testing does sound pretty straightforward after gaining access to the mobo. I've not gone into the machine to that extent before though. Are there any shortcuts for gaining access or is it pretty much follow the bouncing ball in the HMM? I did change out the display several yrs ago so mobo access may not be all that much more daunting. I wasn't here when it decided to quit charging, but I've not noticed any odor emanating from it so the question remains as to why a fuse might have blown. First order of business though is to configure the T60p to stand in while the offending machine is in pieces.

[rkawakami]

Hmm... re-reading your initial post leads me to ask these questions:

If the battery is removed, can the system operate from the AC adapter? If so, then fuse F2 is not dead.

With the battery installed, the system off and the AC adapter connected, does the power/battery LED light up? If so, is it green or orange?

With the battery installed and the AC adapter disconnected, does it show any signs of life when the power button is pressed? I realize that your batteries may be nearly dead but if there's any glimmer of power, then fuse F12 is good.

As to taking the system apart, following the HMM is your best best. However, there's a couple of shortcuts that can simplify things. You don't have to remove the lid assembly in order to check out the top surface of the motherboard. Just remove the keyboard, and possibly the modem/bluetooth daughter card, you should have access to the area where the F2 fuse is mounted. Based on the motherboard image in the T4x fuse map, there's three MOSFETs (power transistors) located near the F2 fuse. Check those parts to see if they look damaged or burnt. To get to the fuse that protects the main battery, you'll have to pull the motherboard out of the base. Fuse F12 is on the back side.

[sbjoe]

Don't know how you managed it Ray, but it appears that you've fixed it. After reading your last post I pulled the battery last night and plugged it in and voila, the bloody thing lit up and the AC icon reappeared in the task bar. After it had finished booting I plugged a battery in and it started charging normally from 5%. Found it 100% charged this morning and just plugged in the second battery. Don't know how long it'll take me to regain confidence in the thing but without doubt you are a wizard. Think I'll just exercise it a bit before I contemplate any further diagnostics.