On Thursday, September 2, 2021 at 8:16, Gavin Scott via cctech wrote: > P.S. The HP Museum has the CE handbook for the 37 and Micro 3000, but > it's in the 3000 Micro XE section. You can find it by searching within > the Documents page linked at the bottom of the left side navigation > bar. > > 3000-37-MicroFamily_CEServiceHandbook_30457-90039_200pages_Feb89.pdf
Page 5-31 of that manual details the LED display codes. Note also that the Series 37 requires certain PCAs to be in certain slots (pages 3-2 and 3-4), so it would be good to verify this too. And as Gavin mentions, the CPU tries to talk to the terminal after completing the self-test, so it's important to have a working terminal connected and turned on when powering up the system. -- Dave