X61T A/C Adapter or Motherboard Problem?

[olex126]

I have a late-production X61T that is still under its' four-year warranty for another few months.

Lately I've noticed a strange anomaly with the charging system and processor speed.

Issue number one arises when I use different Lenovo A/C adapters.  The only way I can get the processor to run at it's top speed of 1.6 Ghz is to use a 90W 20V 4.5a A/C adapter.  If I use the original 65W 20V 3.5a adapter, the processor throttles its' speed back to between 800 Mhz and 1.1 Ghz.  I have a half-dozen Lenovo power supplies, and the issue is the same with any and all of them.

All BIOS and Win 7-x64 power settings are set to maximum processor speed with no power-saving features enabled.

Issue number two is the battery that won't charge.  It has consistently remained at the 13% level for the last month and will not charge. The laptop dies when the A/C adapter is removed, it will not run at all on battery power. I have another battery on the way to test.

My question is, are the two problems possibly related to the power/charging circuits, necessitating a motherboard replacement?

Any help/opinions/suggestions appreciated.

Thanks. Regards.

Dave

[ajkula66 Guru]

Welcome to this forum, old friend...

The issue of  *61 series ThinkPads not running at full speed with a 65W adapter has been well-documented, and points to a bad battery.

For the time being, I'd remove the battery altogether so the charging circuit doesn't get damaged.

[olex126]

Hi George.

Thanks for the welcome to the forum!  I've always just kinda perused this board without ever registering.

I was going to PM you about the power problem, but I know you are a busy man these days, so I thought I'd give a shout here.

Thanks also on the battery info for the X6-series.  Kinda threw me for a loop when I saw it happen the first time.  The tech who replaced the screen suggested it might be a charging problem with the board, and since it is still under warranty, to get it replaced.

Of course when my replacement battery arrives I'll be able to verify the problem either way.

Thanks.  Regards.

Dave

[Mornsgrans]

If the new battery is well, the described problems are gone.

Additional info:

The CPU-speed problem you described concerns to all newer ThinkPad models starting from T/R/X60. If the wall power is not enough, the CPU "pulls" additional power from battery. In case of damaged or missing batteries the CPU keeps the lower speed until a good attery will be attached or a 90W power supply will be used.