• Please review our updated Terms and Rules here

Amstrad pc5086 cmos checksum error

omegals

New Member
Joined
Jun 30, 2012
Messages
9
Hi all,

recently found in the basement my old 5086.
The problem is that sometimes it boots and when
it boots it says 'system cmos checksum bad - run setup".

i have the disk with the DOS in the drive but the light of the drive doesn't flash
& it says "diskette error...".

When i enter the cmos, time and date change themselves.
In the video, I'm only hitting the up arrow on the keayboard.
Whatever change I make to cmos, I press F10 to save & exit
and when I enter cmos again, it hasn't saved any chande I made!

I opened the case and I can't see a battery which I can change
& I don't think that there is clear cmos jumper.

Any help is appreciated. :D

IMG_0145.jpg

[video]http://s904.photobucket.com/albums/ac250/omegals/?action=view&current=MVI_0146.mp4[/video]
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
39,415
Location
Pacific Northwest, USA
There is a battery, somewhere. Second law of thermodynamics and all that...

If you don't see a battery of any sort (including one soldered to the motherboard), it's likely located inside a rather blockish-looking 28-pin DIP.

How about a short of the motherboard so we can take a look?
 

omegals

New Member
Joined
Jun 30, 2012
Messages
9
Forgot to mention before, it always show "keyboard error" allthough
the keyboard works only in XT mode.

IMG_0151.jpg

Here is the motherboard layout :

IMG_0148.jpg
IMG_0149.jpg
 

omegals

New Member
Joined
Jun 30, 2012
Messages
9
IMG_0154[1].jpgIMG_0155[1].jpgIMG_0156[1].jpgIMG_0157[1].jpg

Kinda messy... :(
As you can see pin 16 is definitely disconnected.
Can I proceed with battery?
 

Stone

10k Member
Joined
Nov 3, 2009
Messages
12,814
Location
South Jersey, USA
That's the exact reason why your settings aren't saved after you restart the Amstrad. The settings are stored in the CMOS, which is kept running by the battery.
That may or may not be the case. I've seen lots of systems with their batteries removed that can be rebooted successfully and still retain the CMOS settings. The only time the settings were lost was when the system was powered down. That's because while the system is running the necessary current is available to the CMOS chip and it is able to retain the settings. It was only when the available current was removed and no battery was present that the settings were lost. So, there may be another issue in play here.
 

DOS lives on!!

Veteran Member
Joined
Mar 14, 2011
Messages
2,303
Location
East Tennessee
That also may or may not be true. While certain systems can retain them after a reboot, and some can retain them after a shutdown, some can also reatin the settings when both main power and clock battery were disconnected. As in the case of my Dell System 310, it could retain the settings easily for over 10 minutes without the things mentioned above.

The reason it retained them without a battery is because the main power is keeping the CMOS running, which in turn eliminates the need for a battery, until a complete poweroff.
 

omegals

New Member
Joined
Jun 30, 2012
Messages
9
IMG_0164.jpgIMG_0160.jpgIMG_0161.jpgIMG_0162.jpgIMG_0163.jpg

It is a failure guys. The same as before. Please don't judge the duck tape :ashamed2:
Does anyone know a place where I can buy a new dallas chip?
 

DOS lives on!!

Veteran Member
Joined
Mar 14, 2011
Messages
2,303
Location
East Tennessee
Jameco has them for 7.95 each. That is where I bought mine from. They still have a good charge. You're lucky that the battery was socketed. It's not fun working on (Compaq) computers where they're soldered to the board!

Nice try. ;)
 

omegals

New Member
Joined
Jun 30, 2012
Messages
9
Jameco is not an option for me, they have a minimum order of 30$ for all international orders.
I think ebay is the way to go...
I have a (probably total newbie) question : do I have to buy
any Dallas DS1287 chip or does it have to be exactly the same chip?
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
39,415
Location
Pacific Northwest, USA
Any new chip that you're going to find is going to be a DS12887 (Maxim discontinued the DS1287 a long time ago). You'll probably be okay with the DS12887, however.

Farnell lists them for £13.87 here

Oddly, there's a Chinese seller peddling 5 of them with free shipping for £15 with free shipping from HK.

Do I guess correctly that you're in the UK?
 

Krille

Veteran Member
Joined
Aug 14, 2010
Messages
1,005
Location
Sweden
I've seen lots of systems with their batteries removed that can be rebooted successfully and still retain the CMOS settings. The only time the settings were lost was when the system was powered down. That's because while the system is running the necessary current is available to the CMOS chip and it is able to retain the settings. It was only when the available current was removed and no battery was present that the settings were lost.

In a scenario like this, changing the battery is the best thing to do. However, if changing the battery is not an option (stuck in Dallas hell?), this software workaround might be an alternative.
 

Stone

10k Member
Joined
Nov 3, 2009
Messages
12,814
Location
South Jersey, USA
Is the floppy drive not accessable because of CMOS problems? If so, it's unlikely that you'll be able to successfully install a hard drive either, for the exact same reason.

Once again, I'm not convinced that you have a battery problem although that is still a possibility. The CMOS chip could be bad or there could be another component/circuit on the motherboard that is faulty.

You say you are in Greece... Eisai Ellinas? Pou stin Ellada eisai? Giassou, Petro
 

Krille

Veteran Member
Joined
Aug 14, 2010
Messages
1,005
Location
Sweden
Thank you very much Krille but the floppy drive is not accessible & I haven't got a hard drive installed.
Do you think if I install a hard drive, your program could run?

You mentioned earlier that the computer does not retain the settings across a reboot (warm boot)? If so, my program won't work. Whether you have a harddrive or not is not really relevant. Wangboot is meant to be run from floppy after power up and it immediately restores the CMOS settings (where, among other things, settings for IDE harddrives are stored), then as an optional step it allows you to set the date and time (since that too, is stored in CMOS) and finally reboots the computer so you can use it normally (boot from harddrive etc).

I'm not sure what you mean by "the floppy drive is not accessible". If your floppy drive is completely dead (doesn't spin at all, no LED flashing, no seek noise as part of the POST) then my program won't work of course but if the computer can boot from it or even just tries to boot from it, then my program might work.
 

omegals

New Member
Joined
Jun 30, 2012
Messages
9
Geia sou Petro! Dimitris legomai kai zo stin Athina. Esi apo pou eisai?
Amstrad keeps showing the message "No diskette or no disk found" (or something like that)
It doesn't even trying to read from the drive whenever it shows that message. The floppy
drive led doesn't flash like it's trying to read/write. Strange thing is that whatever floppy
I insert in the drive, it just makes a noise like the motor is spinning all the time until I
take the floppy out & again the led doesn't flash. I don't really have high hopes that a
new Dallas chip is the only solution to my 5086...
Krille, if you see the video that's in my first post, you will get the idea of how messed up
my amstrad is...
 

Stone

10k Member
Joined
Nov 3, 2009
Messages
12,814
Location
South Jersey, USA
Giassou Jimmy, :) Zo stin New Jersey, kounda stin Philadelphia. Philadelphia, now there's a nice name for a Greek city. :) BTW, den eimae Ellinas alla ego echo pai stin Ellada polles fores kai echo mini ekei poly alla kathollo yeia pola kronia.

You might want to try another floppy drive if you have one. But if the CMOS is either corrupt or unable to process the hardware settings I don't think the machine will recognize either a floppy or a hard drive. But it's worth a try.
 
Top