They're not available from Dell -- or for free, but there are sites that do sell them.  Before buying, realize that even if you identify a faulty part or parts, you'll need to have access to a hot air station to even begin repairs, and that's setting aside the fact that unless you live in Southeast China, repair parts are likely to be unavailable to you. If you still want to look for a schematic for purchase, one place to try:   [URL]    
Inspiron 5510, had to change case parts, lid and kb/palmrest, when tested on battery system booted. Completed rebuild and system no longer responds to power button. Removed battery, CMOS, and RAM individually no response, cleared power capacitors etc and tried replacement SSD and alternate AC charging cable. Stripped system, removed all peripherals and attempted power on in isolated state RAM and external monitor only. The system now responds with a micro flash (white) when connected to AC outlet and then flashes orange when power button pressed. This happens with both original and alternate power supply. The orange light will remain if power button continues to be pressed. At this point I am unable to diagnose a problem, the board when checked with multimeter gives some intermittent readings on a couple of components adjacent to the AC inlet and one voltage regulator appears dead - no read in test mode and continuity test is weak or non existent. I think the board has died, but before I consign it, is there anything else I can try? TIA  
Power fail