Three out of three dead octek boards with Headland chipset. Although I think on this it's a mechanical issue. It broke after handling it to try the 287.

I don't believe it. There is actually a datasheet for this chipset.

It hangs after step 04
Source: http://mrbios.com/techsupport/award/postcodes.htm

I found out what killed the 286. A floating protective earth. Same issue as in the kitchen

Lovely

Next thing on the bench: another 286 board.

I've already replaced a bunch of 74F244 buffers and 74F245 bi-directional bus transcievers because they had wonky looking outputs or even inputs

After replacing the 244, its input pins looked good again.

TTL logic levels apply, so <= 0.8V for low, >= 2V for high. In-between is considered undefined.

I love having a DSO. Triggering on these faults is so easy

The situation as of now is that it complains about missing RAM, if that is removed, and initializes the gfx card, but to this.
Post codes are, in reverse order: 30 25 24 23 22 21 20 1a 19 18 17 16 15 12 11 10 0c 0b 0a 09 08 07 06 05 04 14 03 02 01
It hangs after 30. BIOS is an early AMI from minuszerodegrees meant for the 5170.

After 30, Address line 20 goes low and never high again.