[rescue] Sun 386i

[alan at alanlee.org]

Just an update on the 386i and a call for some more help :)

It is a 250.  I replaced the missing chips with 25+ MHz versions of the 
82380 chipset controller, 80385 cache controller, and 80386 CPU.  Not 
sure if the FPU is required or not.  I sourced 12 parity 70ns 1MB 30-pin 
SIMMs.  And I replaced the NVRAM.  I also traced out and inferred the 
DA-15 pinout from the video card.  It seems I have the later revision of 
the monochrome frame buffer.  It initially complained about not 
detecting a keyboard.  But after cut a din cable and connected a Type 4, 
I get @ 9600 baud:

Sun Workstation, Model Sun386i/250, Type-4 Keyboard
ROM Rev 4.4, 12.0 MB memory installed, Serial #6640
Ethernet address 8:0:20:2:19:ef, Host ID: 310019f0.

Promising.  But I never see usable video.  All the signals on the DA-15 
go through isolation inductors including power and ground.  H and V sync 
look good on the scope, but the other two signals that appear to carry 
pixel data are negative to the ground reference (a complication of the 
inductors).  A VGA monitor syncs solid to the H+V syncs, but I get a 
visible black frame with random vertical lines.

The machine does attempt to auto-boot and output over serial.  I set a 
few obvious options in NVRAM via the ROM monitor - board revision, all 
different video modes, and baud rate.  The ROM appears to be reading it 
despite a missing/incorrect checksum (eg. baud options take effect on 
next boot).  The ROM monitor built-in diagnostics all pass: floppy, 
scsi, serial, main ram, video ram, etc).  But I read the NVRAM is fully 
populated by running the diagnostics disk.  I tried both the 4.0.0 
diagnostics disk (diag rev 2.2) and the 4.0.1 diagnostics disk (diag rev 
3.0).  They both run.  But regardless of which tests I enable, I get the 
following error message:

Testing CPU, Takes 1.5 Minutes...


*** CPU Test FAILED ***

Most likely replaceable unit is CPU board
Check for loose cables and try reseating the option boards

--- Remove diskette and press <Return> to restart your system ---

Any clue where to look next?

Thanks,

-Alan