Definitely not a personal computer for the masses, but maybe some national office gem from East Germany.

Resources

Wiki
xepb.org
robotrontechnik.de
retrobrewcomputers.org
Zander (schematics, display adapter)
oldcomputer.info (connectors, pinouts)
Documentation and service manual

Internals

Motherboard

Keyboard

Floppy Disk Controller

Floppy Disk Drives

TEAC FD-55FV-13-U drives – see spec.

Power Supply

That’s really the most impressive part of 1715, solid, heavy, massive and what an attention to details.

Power Supply Fan

Absolutely amazing, aluminium base and super quiet almost zero-friction bearings.

Reassembly