Need help with monitor in Japan

From: Brent Hilpert <hilpert_at_cs.ubc.ca>
Date: Wed Jul 14 14:04:30 2004

"Phab E. Oh" wrote:
> I'm in Japan and having a problem with a US monitor.
> It won't turn on...no power light or power up noises
> or anything.
>
> So I measured voltage across neutral and ground and
> there was 8VAC. So I got an electrician to wire up a
> proper ground. There's still 1VAC across Neutral and
> Ground.
>
> So I have two theories:
>
> 1) The monitor is seeing the floating ground and not
> liking it and refusing to turn on.
> 2) The monitor requires at least 110V (I'm getting
> 103V).
>
> I'd hate to think this thing just died, so can anyone
> confirm that a ground to neutral measurement should
> yield 0V or some very negligible voltage?
>

If you are measuring between GND and neutral, a few volts measured is not surprising (especially with a DMM with a high input impedance), resulting from inductive/capacitive coupling between wires over the distance between your measurement point and where GND and neutral are bonded in the building (assuming that Japan does a straight GND/neutral bond as is done in North America).

The 103V supply voltage is far more suspicious, as it is quite low relative to 115V (you don't say how old the monitor is, could it be that it predates power supplies with 'universal' supply voltage range?). Try finding a power adapter transformer to boost the voltage. (Normal Japanese line voltage is lower than North America isn't it?). Or if you are around electronics people, try to find a variac, as variacs typically have some boost on the upper end of their range (for example, a variac fed with 120V will typically boost to at least 130V, keeping in mind if the variac scale is presented in volts, the scale accuracy will vary with the input voltage). (Or, being very careful not to go to the low end, wire up the variac in reverse).

Or (if the monitor is older) there's always looking inside the monitor for jumpers, or alternative primary taps on a power transformer, to select input voltages.
Received on Wed Jul 14 2004 - 14:04:30 BST