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Thinkpad 755c problem

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nomercy
Posts: 5
Joined: Tue Feb 12, 2019 10:42 am
Location: Kiev, Ukraine

Thinkpad 755c problem

#1 Post by nomercy » Tue Feb 12, 2019 10:51 am

Hey guys, i'm trying to figure out what's going on with my 755c i've just bought.

It starts normally, counts memory, passes tests, starts loading(or i can enter setup), but shortly after this it powers off, "V" lamp became green(like it is in suspend mode). When i try to turn it on back, it beeps two times shortly. Same thing comes when i try to enter setup -- it will poweroff in a small amount of time.
But when i go to diagnostics, it stays in it for any amount of time, i can pass system board test, memory test, and any other tests.
I've tried to take out fdd, additional memory card, battery, and even hdd -- it behaves as i describe.

Need advice where to look for problem. Probably overheating?

nomercy
Posts: 5
Joined: Tue Feb 12, 2019 10:42 am
Location: Kiev, Ukraine

Re: Thinkpad 755c problem

#2 Post by nomercy » Tue Feb 12, 2019 8:35 pm

Seems like standby battery is dead. Can it be a reason?

Thinkpad4by3
Senior ThinkPadder
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Joined: Sun Aug 09, 2015 9:25 am
Location: N. Bellmore, ny

Re: Thinkpad 755c problem

#3 Post by Thinkpad4by3 » Tue Feb 12, 2019 9:56 pm

Standby battery shouldn't prevent it from working.
Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

nomercy
Posts: 5
Joined: Tue Feb 12, 2019 10:42 am
Location: Kiev, Ukraine

Re: Thinkpad 755c problem

#4 Post by nomercy » Wed Feb 13, 2019 5:19 am

Now i think it just going to sleep. Probably lead close sensor, because it often makes screen blank.
Also sometimes it sounds like something was connected. Maybe it thinks that dock is connected, or something like this.

goldeneagle
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Posts: 112
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Thinkpad 755c problem

#5 Post by goldeneagle » Sat Feb 16, 2019 3:26 pm

More than likely, it would be a switch problem. There are two - one where the LCD closes over the keyboard bezel, on the right side, and one under the keyboard. I'd visually check both, or if you don't mind doing some disassembling, check to see if the switches show as open or closed on a multimeter.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

nomercy
Posts: 5
Joined: Tue Feb 12, 2019 10:42 am
Location: Kiev, Ukraine

Re: Thinkpad 755c problem

#6 Post by nomercy » Tue Feb 19, 2019 4:51 pm

Ok, thanks, will check it :thumbs-UP:

nomercy
Posts: 5
Joined: Tue Feb 12, 2019 10:42 am
Location: Kiev, Ukraine

Re: Thinkpad 755c problem

#7 Post by nomercy » Thu Feb 21, 2019 6:10 pm

Fixed by resoldering new capacitors and few pins in power circuit.

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