-main unit working view-

How to dissemble the ERICCSON MC-12 Hand-Held PC case.
(details also apply to the HEWLETT PACKARD HP320LX Hand-Held PC case )

DISCLAIMER: This web-page is to assist in repairing an ERICSSON MC-12 where it exhibits no signs of life, and appears as a non-functioning device, The MC-12 should be out of waranty and the information supplied here is for personal use only. There is no gurantee or waranty implied or otherwise by the author, who made these notes and pictures from a MC-12 unit that was donated as not working. The author is not a professional repairer, but repairs own equipment.
This is quite simple to do, using only a small torx screwdriver, (you will see the size from the screw visible in the battery compartment).
Also recommeneded is wearing anti-static armbands. You may need to clean contacts using Q-Tips and switch cleaner as well.
PLace unit on a soft covering like a towel or cork mat to prevent scratching. The case can be 'poped' apart after undong afew screws ,
or using a scalpel, modeling knife blade or razor blade to begin, then peeling back with something like a plastic letter-opener.
Now the unit is opened various things can be visually examined. Here are a few things I changed to get this unit back in sort-of working order

The supplied Power Supply (125-250V) seems to put out about 5.3V center tip +ve. If the batteries are not charging, you need to go to the battery/power menu when you have got the thing going , and select NiCad and charge. Default is alkaline/not charge.


Example Unit had leaking batteries, so I cleaned the battery spring attachments with a glass-fibre brush and switch lubricant to dissolve the corrosive goo. This can be done without dissasembling the unit, as the terminals are accessable from the battery section.

Pressing the RED RESET button underneath seems to restart the machine from ROM and reload all the default programs ready for use..

The unit I worked on came to life after I cleaned all the connectors: wiped with switch cleaner. flat cable foil is printed, so it doesnt allow much cleaning before it wears off. Then it began from RESET in stylus align mode, and would return to that after pressing return. endlessly going through the aling cycle.. BUT..

I found by pressing repeatedly together: [CONTROL] [WINDOWS] [ALT] [ESC] , it would sometimes jump out of the align loop.

I found that the Jornada 720 WIN CE2 diagnostic Mode works on this device as well: RESET , then IMMEDIATLY press the S character key.

The PIMCA card slot accepts memory cards, after a pause form inserting it. .. but the slot at the other end is for CF memory cards.

Also seems to help to leave the device powered on to get the dispaly going again if it has been left off for years. It slowly got better over a few days of use.

Cleaning the contacts of the connectors, replacing them several times got it going, but some of the vertical lines on the display were missing. -keyboard  screws view - -keyboard  screws view - SO I made the screen fully dark: press [ALT][>] repeating untill the display goes dark all over in case that re-invogorated the LCD.
The BLUE [BRIGHT] button to the left of the space bar is usefull to tell the keyboard is working as the background light comes on if it is working.

Starting some programs made the screen go blank, but darkening the display using keys: [ALT[ [>] showed that some programs are using the display differently. If that didnt work [CTRL][ALT][DEL] brought up a window to cancel invisible program.

Did not see any big capacitors split or 'domed' or anything that looked wrong with the unit.so just cleaning connectors seems to have worked.

After I got the unit going , Had a look around to see what applications were default. The ERICSSON MC-12 and HP320LX and similar units are not much good for communications or surfing the net nowadays, as so many websites need flash or AJAX or other technologies. The inbuilt CE version of EXCEL WORD etc is very basic. but it is instant-on and usefull perhaps for note-taking where you wouldnt take a laptop. The technology was at the forefront in 2000 therabouts, units cost about £ 400 or more then. A restored unit could fetch about £ 50 to £ 100 in fully working order on E-Bay, Mainly for collectors of unusal gadgets of historical interest.
LINK to ERICSSON MC-12 Specification sheet on PDADB website

LINKS to EBAY for gadgets  LINK  to EBAY

Good Luckwith your repair !

© Martin Macrae March 2012