NEC "MPC 1003C" chip
I am restoring an old ROTEL turntable and have come across a "NEC MPC1003C" chip [...] I can not find any information on the internet.


There doesn't seem to be much information available anyway, but you need to use the correct part number for the best chance of finding anything.

Although written on your schematic as "MPC 1003C", the correct NEC part number of this IC from the 1970s is:


&mu;PC 1003C


it is sometimes also written as:


&mu;PC1003C
(no space between letters and numbers)
uPC1003C
(NEC used the small Greek letter "Mu", but that is frequently replaced by the similar-looking small letter "u")
uPC1003
(I have read that the original IC was the uPC1003, and that the uPC1003C and uPC1003C2 were later versions)
UPC1003
(all capital letters)

and similar variations.


I can only guess that organisations who wrote "MPC 1003" on their schematics, as in the one you supplied, actually capitalised the Greek letter "Mu" (a capital Greek "Mu" looks like a capital letter "M").


  acting (I think) as voltage regulator


Actually that IC is some kind of servo motor driver - notice the feedback signal from the motor to pin 1 on the IC. It was used in some 1970s (and 1980s?) tape recorders and turntables, to maintain speed control of the motors. You will sometimes find it mentioned on vintage audio forums.

You can try using the part numbers I have given above (perhaps starting with uPC1003) to search for what little information seems to be available. A few of the ICs still appear to be for sale (as "new old stock" / NOS), although production seems to have stopped a long time ago. I didn't find a datasheet, but by using the correct part number in your future searches, you have a chance for more success.