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Laptop power supply repair

D

Daniel Prince

Jan 1, 1970
0
I use my Lenovo IBM THINKPAD T60 1953 in bed. When I am not using
it, I put it into a garage I made on the side of my bed. I bought
the laptop used in April 2008. In late July 2008 the cable of the
power supply started to fail. It would connect and disconnect
itself when it was moved slightly.

I bought a replacement power supply. It failed a few months later.
This time, I cut it open and repaired it using solder. I had to
repair it again a few months after that.

Yesterday, It failed for a third time. This time I repaired both
the replacement power supply and the original supply so that I would
have a spare. I tested both supplies. They both worked.

I used one of the supplies (the original one) for a few hours. This
morning, my laptop made the ding dong sound it makes when the AC
power is disconnected and the AC indicator light did not light.

I thought that the repair I had made had failed. I connected the
other power supply but it did not light the AC light either. I
tested both power supplies with a volt meter (not connected to the
laptop). They both tested good. (These supplies are rated 20
volts. One was 20.1 volts and the other was 20.3.)

I have tried both supplies several times and neither of them make
the AC indicator light up and the says that it is on battery power
with the battery charge going down. Obviously the laptop is not
getting AC power.

Does anyone have any idea what could be wrong and how I can fix it?
Thank you in advance for all replies.
 
J

JB

Jan 1, 1970
0
Just make sure you take ESD precautions or you will likely wind up with a
paper weight.

Wild_Bill said:
I think Jerry's conclusion is likely to be the problem you're experiencing
now. Opening laptop cases can be a bit complicated at times, but I think you
may find the instructions at the Lenovo website.

Locating a new power connector for the motherboard would probably be a wise
move if you intend to repair the problem yourself.
I've seen various new laptop motherboard power connectors on eBay, but it's
likely that numerous online parts vendors would also be selling them.

Straight power cord connectors typically put more stress on the power
connection than right-angled connectors do, but manufacturers insist on
using straight connectors in most cases, as they may be a couple of cents
cheaper (SWAG).

A right-angle connector, in combination with a temporary anchor point on the
instrument's case near the port, would be a much more durable connection.
 
D

Daniel Prince

Jan 1, 1970
0
larry moe 'n curly said:
I don't like using laptops on my laptop because it blocks the air flow
underneath, and moving around the hard disk so much can't be good for
it.

I keep my laptop on a laptop cooler with two fans. The cooler I
keep on a plastic cutting board. I put the cutting board on a
pillow on my lap. I think both my lap and the computer stay cool
enough.
 
D

Daniel Prince

Jan 1, 1970
0
larry moe 'n curly said:
I find it hard to believe that two power packs would fail, especially
when they each measure normally, but have you tried measuring each
while a 10-100 ohm load is applied to the DC output?

I pulled enough of the electrical tape off of one of the supplies so
that I could measure the voltage with it plugged into the laptop.
The voltage was still 20.1 volts.
 
D

Daniel Prince

Jan 1, 1970
0
Meat Plow said:
Well if you want to peel the laptop apart, inspect the connector and
soldering.

I bought a new power jack and it plugs in to the motherboard rather
than being soldered. I got a service manual pdf file and it says
that the screws used in the Thinkpad are nylon coated and should not
be reused. Is it really necessary to use new screws?

The manual does not really say how to replace the power jack. It
does say that to replace the 1200 Structure frame, I need to:

For access, remove these FRUs, in order:
v “1010 Battery pack” on page 63
v “1020 Ultrabay Slim device” on page 64
v “1030 Hard disk drive cover, hard disk drive, and hard disk drive
rubber rails” on page 65
v “1040 Palm rest or palm rest with fingerprint reader” on page 67
v “1060 Keyboard” on page 75
v “1070 Modem daughter card (MDC-1.5)” on page 77
v “1080 PCI Express Mini Card for 802.11 a/b/g wireless LAN” on page
79
v “1100 PCI Express Mini Card for wireless WAN” on page 83
v “1120 Keyboard bezel and wireless WAN antenna cable (AUX)” on page
86
v “1130 Fan assembly” on page 89
v “1150 LCD assembly” on page 94
v “1160 Base cover” on page 98
v “1190 SIM card slot” on page 1061

Then it says to

Remove the ac power jack cable.

I am hoping that I will not have to remove all those parts. Do you
know which ones I will have to remove?
 
J

JB

Jan 1, 1970
0
Well if you want to peel the laptop apart, inspect the connector and
I bought a new power jack and it plugs in to the motherboard rather
than being soldered. I got a service manual pdf file and it says
that the screws used in the Thinkpad are nylon coated and should not
be reused. Is it really necessary to use new screws?
You will find out as you take it all apart at your large ESD prepared bench.
Be aware of type and length of screws and other odd hardware as you take it
apart them. If you put a long screw in a short hole, or miss a shim or
washer, it will dimple the outside surface, short something or break the
retainer. Pay close attention. A digital camera and quick sketch has been
handy. If the screws are Nylon coated, then use a spot of Permatex thread
locker blue. If they are nylon screws, they will likely distort or break
the heads off if over-torqued.

Power Jack plugs into MOBO? If you say so. How do you replace the jacks
that the jack plugs into? Bet it's soldered. The answer would have been a
replaceable jack bolted to the frame with a cable to the MOBO rather than
directly to the MOBO, but that would have been .0001c too much for large
scale production cost. You must realize that cost is a far greater concern
than customer satisfaction, or everybody would be taking the garbage back to
where they bought it for a refund. People would be sitting at a desk in an
air conditioned room with an expensive piece of office equipment rather than
taking a cheap toy out to play in the dirt.

If the screws are Nylon coated, then use a spot of Permatex thread locker
blue. If they are nylon screws, they will likely distort and break the
heads off if over-torqued. If you put a long screw in a short hole, it will
dimple the outside surface, short something or break the retainer. Pay
close attention.
 
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