A21m doesn't do a thing

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renevanh · #1 Post by **renevanh** » Sun Jul 15, 2007 10:58 am

About 1 year ago, my A21m stopped working. I figured it was the motherboard, but I left it untouched for several months. Recently, I bought a new motherboard, CPU and a CPU fan that would fit. After I installed these parts, the laptop still didn't work. I replaced the sub card and even the CMOS battery, but still no luck. The laptop does power up, but I don't get a boot screen or POST and I don't get any beeps when I remove everything excepts the sub card and the keyboard (so I can power up

). I know it can't be the LCD screen, because I don't get anything on an external monitor either.

I know there are various power problems known with the A2x series, but all known solutions and tips wouldn't work for me.

Anyone got an idea? Could it be the replacement motherboard that is just not working, or could it be something else?

René

renevanh · #2 Post by **renevanh** » Tue Jul 24, 2007 2:59 am

Nobody can give me a tip or something?

René

madmax · #3 Post by **madmax** » Wed Jul 25, 2007 10:03 am

At best you need to doublecheck all connections and
output voltages to motherboard...

This flow chart may help

http://www.daileyint.com/hmdpc/lappower.htm

Troubleshooting comes from experience and logical elimination
of possible faults... keep varibles at a minimum.

Sorry I can't help more... good luck

renevanh · #4 Post by **renevanh** » Wed Jul 25, 2007 10:52 am

Thanks for the link.

The flowcharts guide me to a board failure, probably the video chipset.

New motherboard I guess...

René

waynesdukeess · #5 Post by **waynesdukeess** » Fri Jul 27, 2007 12:14 am

Hi, I don't have much luck with TP MBs out of 21 i have checked
only fixed 3, Rember on EBAY you can now get good MBs for
$30-60,

How i check and maybe repair:

Bare MB on insulated bench, Memory if needed, pw subcard if
needed
1. connect ac power adapter, if LED light flash, good
2. disconn pw, connect: External video monitor, keyboard
connect power, most LED lights should flash and IBM logo
on monitor with options F1,F12 and F11(if enabled in setup
bios).
3. if you get into setup bios MotherBoard should be good.
4. Remove power, With great care plugin harddrive, lots of
good memory, should see OS booting up on screen.

MB seems bad, no lights nothing
1. with bare MB apply power. take volt meter, clip black lead
to metal by the comm and lpt(printer) connectors.
2. meter on 20volt dc(or higher) range, contact the red tip to
the power center tip going into the MB, read about 16 volts. try to trace your way through pw connector(these are
broken loose) , 16volts should be on both sides of little white fuses(F!,F2,etc), and + side elect. capitors( little gray cans)
3. IF pw(16volts) lost about halfway MB could have short
or shorted components powersulpply voltage regulators
in current limit. LOST CAUSE TOO MUCH MONEIES AND
TIME TO FIX. you can not get dwgs.or info behond this point.

4. check out here or ebay for parts. I have bought 3 A20s
$30ea all MB were good except one had supv PW loc
made 2 good laptops for the school kids

Good luck

renevanh · #6 Post by **renevanh** » Fri Jul 27, 2007 3:48 am

I just don't get the boot screen or the BIOS, the screen stays black.

René

waynesdukeess · #7 Post by **waynesdukeess** » Fri Jul 27, 2007 10:35 am

HI agin, If LED lights seem to be flashing normal and you have no video on Laptop LCD or a pluged in external monitor the video part
of MB is bad. MB isno good. BUT TRY PECKING(TAPING hARD) KEYS fN AND f7. AND DON'T FORGET EBAY TP A20s for parts $30.

luck, Wayne

renevanh · #8 Post by **renevanh** » Fri Jul 27, 2007 11:34 am

LED's are ok, no beeps though.

I tried an external monitor and Fn+F7, but I don't get anything.

I know the offerings at Ebay (bought this motherboard there).

René

waynesdukeess · #9 Post by **waynesdukeess** » Fri Jul 27, 2007 4:53 pm

HI, IF the harddrive light was flashing, you had good cpu, memory
and working harddrive. it just seems odd if your old MB checks out the same. do you have good memory to plug in ( there is no
memory on MB).

luck

renevanh · #10 Post by **renevanh** » Fri Jul 27, 2007 5:25 pm

Both new and old motherboard are doing exactly the same.
The LED's light up, the CPU fan and HDD are spinning, but there are no beeps (even when memory and/or CPU is taken out) and there is nothing om my screen or external monitor.

Since I already replaced a working sub card it must be the motherboard...

René

#11 Post by **Harryc** » Fri Jul 27, 2007 7:19 pm

What voltage do you measure coming out of the center pin at the end of the AC adapter cord?

renevanh · #12 Post by **renevanh** » Sat Jul 28, 2007 3:55 am

It's almost constant 15.59V with sometimes (about ones every 30 seconds) drops to 14.8V.

René

#13 Post by **Harryc** » Sat Jul 28, 2007 4:45 am

According to the MIM the tolerance on that output is +15.5 to +17.0. You are below specs on it.

ftp://ftp.software.ibm.com/pc/pccbbs/mo ... 3p0896.pdf

renevanh · #14 Post by **renevanh** » Sat Jul 28, 2007 5:08 am

I think that's hard to say...

Voltage mesurements are always the difference between two points, in this case the + and - of the AC adapter.

If there are other electronic devices on the same power circuit (and there are) and one of them is leaking a few volts, it might interupt the measuring...

I plugged the AC adapter in a free power circuit (nothing else on the group), and the output is a constant 15.82V without any drops (measured for 3 minutes)

René

waynesdukeess · #15 Post by **waynesdukeess** » Sat Jul 28, 2007 10:59 am

Hi ,

Don't forget MB work just fine on 10.5 volts from the battery.

Sometimes I will slide the battery in to make conn and power up MB. IF ok Plug in AC Pw adapter to see if charging and LED lights come on.

luck, the way you describ you need another MB

SMA · #16 Post by **SMA** » Sat Jul 28, 2007 1:32 pm

The AC adapter is almost the only relevant thing you haven't tried to replace.

renevanh · #17 Post by **renevanh** » Sat Jul 28, 2007 4:02 pm

SMA wrote:The AC adapter is almost the only relevant thing you haven't tried to replace.

Because I almost certain it's ok.

When I boot on the battery there is no change, and the battery is a new one.

René

A21m doesn't do a thing

A21m doesn't do a thing

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