Thank you MDX 400.
Yes, the voltage used by the AC adapter is 4.5 V.
See, the adapter I bought is a 4.5 V. / 700 mA.
The original (european) is 500 mA.
I couldn't find one running on 500 mA, besides, I thought that having more "juice" it should be better.
Anyhow, as you say and, as I guessed, the problem should be from the power cord down.
My strong feeling is that the EIAJ, although it fits the AM-F5, doesn't make proper contact.
I am not a hell of a technician when it comes on wiring etc.
But here goes one question:
what if I cut a segment of the power cord with the EIAJ off the european adapter and sold it to the new one ?
How would I know the polarity?
On the Radio Shack adapter the wires of the power cord are both white.
Which one would be which?
I would like to try, if possible, the above solution.
The travel transformer thing it would be too complicate and expensive, because I would need a transformer that convert from 120 ACV to 230 ACV to use the original adapter.