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hi, i've seen from the service manual here that the VL-1 has a variable resistor labelled "VR1" that (i guess) should allow 5V power input.
Since 5V/USB power adapters are everywhere nowadays i'd like to do the same mod on an old PT-10 keyboard, if it has the same resistor.
I also guess i will need to add a resistor to use the batteries after that...
Last edited by eadmaster (Jan 6, 2016 12:43 am)
What makes you think that VR1 allows you to power the thing with USB? VR1 as listed in the manual is for setting VDD to -3v.
EDIT: I see what you're seeing now. If you could turn VR1 to a point that works with +5v instead of +6v, then you could actually add a voltage regulator to the 6v input to bring the voltage down to +5v and mix them together with some diodes. That way your battery compartment could still be used. I think.
Last edited by Jazzmarazz (Jan 6, 2016 1:08 am)
are the voltage regulator and the diodes required for the batteries?
If i only use the AC adaptor can i just lower the resistor?
Last edited by eadmaster (Jan 6, 2016 2:33 am)
Thats hard to say. I am not familiar with the circuitry from the wall wart. I suggested the diodes in case you were to accidentally use multiple power source at once. But if you made sure never to use anything besides the USB, then you wouldn't need them.
I am not really sure about this, but it may even work without modifying the variable resistor, since 5V is within the range of what 4xAA batteries can provide.
For the same reason fake batteries like these should work without issues (i am definitively gonna try this sooner or later).