A 100 series adaptor provides more current than the Portable's adaptor and is often enough to get it going. The best adaptor to use is that for the 165c and 180c (M5652) as it provides more current than earlier adaptors. If the Portable won't start then try holding down the programmer's switch and restart button (on the left hand side) for 10 seconds then press a key on the keyboard. You may need to repeat this several times.
Alternatively try to find another 6V lead acid battery and wire it to the battery contacts. There are batteries available new that are practically the same as the Portable's original battery, but unfortunately I don't know any part numbers etc.
Another alternative is to use a 6V DC generic power supply wired directly to the battery contacts inside the portable. If playing around with wires on the contacts take care of the polarity (looking from the front of the machine the left contact is positive and the right negative). The positive contact also has an insulating square of plastic around it (though Portables made your side of the Atlantic may be different).
Alternatively try to find another 6V lead acid battery and wire it to the battery contacts. There are batteries available new that are practically the same as the Portable's original battery, but unfortunately I don't know any part numbers etc.
Another alternative is to use a 6V DC generic power supply wired directly to the battery contacts inside the portable. If playing around with wires on the contacts take care of the polarity (looking from the front of the machine the left contact is positive and the right negative). The positive contact also has an insulating square of plastic around it (though Portables made your side of the Atlantic may be different).