It‘s a Chaintech 416SX/420SX/425SX/433SC/450SC with a 486DX50 and 4x4 MB. I had thread about it like 3 years ago because it would always give a controller failure.
Well, the other day I decided to grab this board from the basement, mainly because I got a beautiful AT case with a display that shows 50MHz 🙂.
After pulling the BIOS chip I cleaned the socket with deoxid and now it works…somewhat.
First, it‘s very slow. After memory count there‘s the usual beep but it takes like 5 seconds before POST continues. Then, after POST, it takes about 10 secs before the booting (from FDD) starts.
I have a 250MB Conner HDD which does work: I installed DOS 6.22 and made it bootable but the PC won’t boot from the HDD. It says ‘missing OS’ in german language??????
The disk is not empty and it did come from I long sold 286, all the stuff still on it is in german but the DOS version is definitely english.
Also the CD-ROM drive won’t work. The driver installs, it has a drive letter assigned but it gives an error when I want to access the CD.
I loaded BIOS defaults, changed ISA CLK to 1/6 but that didn’t do anything.
Scandisk’s surface scan crashed with a runtime error after finding bad sectors in the middle of the disk - never seen that before.

So, any ideas?
I do have a 544mb Seagate disk - when I can find it I’ll test that one. Other than that I don’t really know what else I should look for.