CP290 Computer Interface
I have never seen a 110V CP290 inside, the one I had was already modified for 220V so I will try to "reverse engineer" what they did to modify it. It is a little bit difficult to describe it in only words, so I will try to use some ASCII graphics. Be sure to use a non proportional font if you want to at look at this or if you want to print it out. I made the ASCII graphics before I even thought about converting this to HTML!
If you think that this modification is too complicated, you could always use the transformer/capacitor trick instead. See end of the part about general modications priciples: General modification priciples
Remove the battery and open the CP290. One screw is inside the battery compartment and the other three under the self adhesive rubber feet. Take out the pcb.
Hold the pcb so the incoming cable is pointing downwards and compare the left bottom corner with this drawing.
| || | |
| XXXXX
| || | | ,-----------O
| XXXXX The DIN connector
| || | | / /
O Big pads
| || | | O O
O-' 0 Big pads with power cable
| |\ /o | | |
o o Small pads
| \ \ / / | O O `--O-,
-/\|`', Tracks
| \ \| | / | \
| _| Edge of board
| o|| o | /
\ |
| o |o | o o o\
o---o o
| `--' | \
/
| / o--------'
| o 0 0
| \o
| XXXXXX
| XXXXXX
`_______________________________
I will now put in some symbols to help you identify things.
| || | |
| XXXXX
| || | | ,-----------O
| XXXXX The DIN connector
| || | | / /
O Big pads
| || | | O O 4
O-' 0 Big pads with power cable
| |\ /o | | |
o o Small pads
| \ \ / / | O O `x-O-,
-/\|`', Tracks
| \ \| | / | \ 5
| _| Edge of board
| o|| o | / 1
\2 3 | x
Where to cut a track
| o |o | o o o\
o---o o6 . Drill a 1mm hole here
| `--' | \
7 . /
| / o-x------'
| o 0 0 A
| \o
| XXXXXX
| XXXXXX
`_______________________________
Remove C1 which is installed between pad 3 and 6 OR between 2 and 6. Cut the track between pad 4 and 5 and the track between pad 6 and 7. The letter "x" show were to cut. Drill a 1mm hole between pad 2 and 3, where the "." is. This hole should be just between the two tracks and not be too close to any pad or track.
Scrape away the paint on the track going from point "A" towards the cut you just made. Install 0.22uF/400V polyester capacitor in the new hole and pad number 1. Solder pad 1 and solder the other end to the place were you just removed the paint.
Install another 0.22uF/400V polyester capacitor between pad 2 and 6. This is where C1 was mounted. Just as a safety precaution, improving the insulation distance, cut the track between pad 2 and 3 . Finally install an insulated jumper between pad 1 and 4.
Reassemble and change the plug to your favorite type.
This looks like what they did to modify the CP290 but as usual, I take no responsibilities. Send me a mail to confirm if it works and I will try to confirm this in the next version of this file. Don't send me mail if smoke is coming up or if it does not work!