Controller 1 STUCK left

[hitechcd]

I have to rule out the usual solder problem, as I have used a mutltimeter and tested continuity to the offending PIN (3rd one in, top row).  There is continuity right to the Sega controller chip nearby.

This is a voltage problem - all of the other controller pins have 5 volts UNTIL a button is pressed, which it then grounds to near zero.

This particular pin has a constant .47 volts all the way to Sega controller chip.

So...  QUESTION:  where does the 5 Volts originate from to power all of the controller buttons?  Is it from that Sega Chip?  If so, is that chip toast?

This is a Master System Power Base model 1.  I have tested this on multiple games with multiple controllers - and each game player 1 is STUCK LEFT.  For example, on Hang ON the BIKE is tiled left forever.  On Teddy Boy, Player one keeps walking left, while I have full control on Player 2.

Thanks for any help.  I don't want to have to trash this machine if it is fixable.

[Maxim]

The chip has an internal pull up to VCC which the controller shorts to ground. It sounds like the chip is toast.

[hitechcd]

Thanks for quick reply:  I was hoping the 5 volts came from somewhere else that I could bypass or re-solder.

This is a really clean machine except for the controller damage.  Video and Sound are crystal clear, Carts and Cards boot right up...