Here's how to change the mains voltage setting on an A4000. Don't forget that this will only change the mains voltage, it won't help with PAL/NTSC problems or 50/60 Hz scan rates.
The PSU, although labelled "230 V", or "115 V", will work over quite a large voltage range. It's not specified on my PSU, but it's usually 100-130 V or 200-260 V. The frequency (50 or 60 Hz) is immaterial for the PSU.
The procedure that follows affects mains voltage wiring and components. Do not attempt it if you have any doubts about it. If you are doubtful, take the PSU to someone who knows his/her stuff. Don't blame me if it screws up.
OK now, my 4000 is a 230V one, 145W output. The PSU is a Skynet, made in China.
On my PSU, the link is already removed (naturally, for a high voltage input), but I can see where it goes and I've traced out the circuit to check it's the right place.
[Explanation:
The PSU on high voltage (230V) uses the internal bridge rectifier as a full wave bridge, giving out about 340V dc for the PSU. When you insert the link, it short circuits part of the rectifier circuitry and makes it into a voltage doubler for low (115 V) input. The resulting dc is about the same. Since no extra components are required, PSU manufacturers include the circuit board tracks so that an OEM can include an external voltage switch, a link, or nothing.]
This describes my 4000 and PSU - your kilometerage may vary with different models :-D .
Remove the power cable from the rear of the 4000. You may leave all the other cables connected if you have room to work.
Remove the top cover by unscrewing the two screws at the top rear of the cover (one at each corner).
The plastic front panel is secured to the chassis by six clips that protrude into the front of the chassis.
Remove the front panel by squeezing the plastic clips together and pulling the panel off gently. You will have to bend it slightly to get the clips off one at a time. When the cover comes away, leave it attached to the chassis with the cables if you like. I usually turn it round on top of the chassis.
Remove the long plastic switch actuator.
The front disc drive assembly is secured by two screws on ears into the front of the chassis. Remove these two screws and slide the drive assembly forward about 5 cm.
Check that the power cable is disconnected.
Now remove from the rear of the chassis the remaining screw that holds the PSU, and the two countersunk screws securing the rear disc drive assembly to the cover of the PSU.
There should be no reason to disconnect all the dc cables from the PSU unless you want to remove it completely for cleaning, replacing the fan, or whatever.
Slide the PSU forwards until it clears the lip on the rear inside of the chassis. It can then be lifted over the side edge and rotated out of the chassis (still connected).
On the side of the PSU, at the bottom, motherboard side, are two screws that secure the cover of the PSU. Remove these two screws and swing the cover up and off the PSU.
Now you can see the inside of the PSU. You DID remove the power cable, didn't you?
Assuming you are facing the PSU and the mains connectors are close to you, look at the board in the box. There are two capacitors about 15 mm diameter and 25 mm high on the board, right hand side as you look at it. Between them is a wire link labelled "J1". This link must be IN for 115 V and OUT (removed, cut out) for 230/240V.
To change your PSU to 230/240 V operation, just cut the link with a small pair of cutters. You should not have to remove the board from the box unless you want to replace the fan at the same time.
[Edit: you can change a 230 V PSU to a 115 V PSU by installing the link, but you will have to remove the board and do some soldering.]
Don't leave the cut bit of wire lying inside the box.
Reassemble. The PSU and front disc drive assembly are held to the bottom of the chassis by a metal tongue that engages a slot. There is no screw involved, but some messing about may be needed to get the tongue to engage the slot. Be careful that the cables to the drives are not caught by the tongue and slot.
Don't forget to reinstall the plastic power switch actuator before replacing the front panel.
With a felt pen, write the new voltage setting on the rear of the PSU. You don't want to dismantle it again to check if it's the one you changed.
Good luck :-D
tony
