IBM 5140  -  Documentation Pointers

"An Introduction to the PC Convertible"

Pages 1110-1115 (PDF pages 1142-1147) of Upgrading and Repairing PCs - Tenth Anniversary Edition

IBM manual - 'Technical Reference'

There is a link to the technical reference here.

Additional information

There is a lot of good technical information on the IBM 5140 page at ohlandl.ipv7.net;  a link to that page is here.

Power supply

See the VCF threads at here and here.